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Background Gait impairment leads to increased mobility decline and may have neurological contributions. This study explores how neurological biomarkers are related to gait in older adults. Methods We studied participants in the Cardiovascular Health Study, a population-based cohort of older Americans, who underwent a serum biomarker assessment from samples collected in 1996–1997 for neurofilament light chain (NfL), glial fibrillary acidic protein, ubiquitin carboxy-terminal hydrolase L1, and total tau (n  = 1 959, mean age = 78.0 years, 60.8% female). In a subsample (n  = 380), cross-sectional associations with quantitative gait measures were explored. This subsample was assessed on a mat for gait speed, step length, double support time, step time, step length variability, and step time variability. Gait speed was also measured over a 15-ft walkway annually from 1996–1997 to 1998–1999 for longitudinal analyses. Linear regression models assessed cross-sectional associations of biomarkers with gait measures, whereas mixed effects models assessed longitudinal gait speed change from baseline to 1998–1999. Results Neurofilament light chain was significantly associated with annual gait speed decline (standardized β = −0.64 m/s, 95% CI: [−1.23, −0.06]) after adjustment for demographic and health factors. Among gait mat-assessed phenotypes, NfL was also cross-sectionally associated with gait speed (β = 0.001 m/s [0.0003, 0.002]) but not with other gait measures. None of the remaining biomarkers were significantly related to gait in either longitudinal or cross-sectional analyses. Conclusions Higher NfL levels were related to greater annual gait speed decline. Gait speed decline may be related to axonal degeneration. The clinical utility of NfL should be explored. [ABSTRACT FROM AUTHOR]

Gait impairment leads to reduced social activities and low quality of life in people with Parkinson's disease (PD). PD is associated with unique gait signs and distributions of gait features. The assessment of gait characteristics is crucial in the diagnosis and treatment of PD. At present, the number and distribution of gait features associated with different PD stages are not clear. Here, we used whole-body multinode wearable devices combined with machine learning to build a classification model of early PD (EPD) and mild PD (MPD). Our model exhibited significantly improved accuracy for the EPD and MPD groups compared with the healthy control (HC) group (EPD vs HC accuracy = 0.88, kappa = 0.75, AUC = 0.88; MPD vs HC accuracy = 0.94, kappa = 0.84, AUC = 0.90). Furthermore, the distribution of gait features was distinguishable among the HC, EPD, and MPD groups (EPD based on variability features [40%]; MPD based on amplitude features [30%]). Here, we showed promising gait models for PD classification and provided reliable gait features for distinguishing different PD stages. Further multicenter clinical studies are needed to generalize the findings. [ABSTRACT FROM AUTHOR]

Background Wearable devices have become widespread in research applications, yet evidence on whether they are superior to structured clinic-based assessments is sparse. In this manuscript, we compare traditional, laboratory-based metrics of mobility with a novel accelerometry-based measure of free-living gait cadence for predicting fall rates. Methods Using negative binomial regression, we compared traditional in-clinic measures of mobility (6-minute gait cadence, speed, and distance, and 4-m gait speed) with free-living gait cadence from wearable accelerometers in predicting fall rates. Accelerometry data were collected with wrist-worn Actigraphs (GT9X) over 7 days in 432 community-dwelling older adults (aged 77.29 ± 5.46 years, 59.1% men, 80.2% White) participating in the Study to Understand Fall Reduction and Vitamin D in You. Falls were ascertained using monthly calendars, quarterly contacts, and ad hoc telephone reports. Accelerometry-based free-living gait cadence was estimated with the Adaptive Empirical Pattern Transformation algorithm. Results Across all participants, free-living cadence was significantly related to fall rates; every 10 steps per minute higher cadence was associated with a 13.2% lower fall rate (p  = .036). Clinic-based measures of mobility were not related to falls (p >.05). Among higher-functioning participants (cadence ≥100 steps/minute), every 10 steps per minute higher free-living cadence was associated with a 27.7% lower fall rate (p  = .01). In participants with slow baseline gait (gait speed <0.8 m/s), all metrics were significantly associated with fall rates. Conclusion Data collected from biosensors in the free-living environment may provide a more sensitive indicator of fall risk than in-clinic tests, especially among higher-functioning older adults who may be more responsive to intervention. Clinical Trial Registration NCT02166333 [ABSTRACT FROM AUTHOR]

Background: Understanding the pathologic bases underlying the heterogeneity of motor decline in old age may lead to targeted treatments. We examined whether different brain pathologies are related to declining grip strength and gait function.Methods: We examined postmortem brains of older adults who underwent annual motor testing. Postmortem exam measured six neurodegenerative and five cerebrovascular disease (CVD) pathologies. Grip strength was measured twice bilaterally using a hand-held dynamometer and gait function was a composite measure based on time and steps taken to walk 8 ft and perform a 360 o turn twice.Results: In separate linear mixed effects models including all autopsied adults (N=1217), neurodegenerative pathologies including tau tangles, TDP-43, and nigral neuronal loss were associated with declining grip strength, but not CVD pathologies. In contrast, while both CVD and neurodegenerative pathologies were associated with declining gait function, CVD pathologies accounted for 75% of the variance of declining rate of gait function explained by brain pathologies and neurodegenerative pathologies accounted for 25%. These findings were unchanged in adults (n=970) without a history of stroke. Restricting analyses to only adults without dementia (n=661), CVD pathologies continued to account for the majority of the variance of declining gait. However, we failed to detect in this subgroup variance of declining grip strength explained by neurodegenerative or CVD pathologies.Conclusion: Different pathologies accumulating in aging brains may contribute to the phenotypic heterogeneity of motor decline. Larger studies are needed in older adults without dementia to assess differences in the motor consequences of varied brain pathologies. [ABSTRACT FROM AUTHOR]

Background: It is important to understand the factors associated with life-space mobility so that mobility disability can be prevented/treated. The purpose of this study was to identify the association between mobility determinants and life space among older adults.Methods: This study was a cross-sectional analysis of 249 community-dwelling older adults (mean age = 77.4 years, 65.5% female, 88% White), who were recruited for a randomized, controlled, clinical intervention trial. Associations between cognitive, physical, psychosocial, financial, and environmental mobility determinants and the life-space assessment (LSA) at baseline were determined using Spearman's correlation coefficients and one-way analysis of variance. Multivariate analysis was performed using multivariable linear regression models.Results: The mean LSA score for the sample was 75.3 (SD = 17.8). Personal factors (age, gender, education, comorbidities), cognitive (Trail Making Test A and B), physical (gait speed, lower extremity power, 6-Minute Walk Test, Figure of 8 Walk Test, tandem stance, energy cost of walking, and Late-Life Function and Disability Function Scale), psychosocial (Modified Gait Efficacy Scale), and financial (neighborhood socioeconomic status) domains of mobility were significantly associated with LSA score. In the final regression model, age (β = -0.43), lower extremity power (β = 0.03), gait efficacy (β = 0.19), and energy cost of walking (β = -57.41) were associated with life space (R2 = 0.238).Conclusions: Younger age, greater lower extremity power, more confidence in walking, and lower energy cost of walking were associated with greater life space. Clinicians treating individuals with mobility disability should consider personal, physical, and psychosocial factors when assessing barriers to life-space mobility. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study was to examine whether select baseline characteristics influenced the likelihood of an overweight/obese, older adult experiencing a clinically meaningful gait speed response (±0.05 m/s) to caloric restriction (CR).Methods: Individual level data from 1 188 older adults participating in 8, 5/6-month, weight loss interventions were pooled, with treatment arms collapsed into CR (n = 667) or no CR (NoCR; n = 521) categories. Exercise assignment was equally distributed across groups (CR: 65.3% vs NoCR: 65.4%) and did not interact with CR (p = .88). Poisson risk ratios (95% confidence interval [CI]) were used to examine whether CR assignment interacted with select baseline characteristic subgroups: age (≥65 years), sex (female/male), race (Black/White), body mass index (BMI; ≥35 kg/m2), comorbidity (diabetes, hypertension, cardiovascular disease) status (yes/no), gait speed (<1.0 m/s), or inflammatory burden (C-reactive protein ≥3 mg/L, interleukin-6 ≥2.5 pg/mL) to influence achievement of ±0.05 m/s fast-paced gait speed change. Main effects were also examined.Results: The study sample (69.5% female, 80.1% White) was 67.6 ± 5.3 years old with a BMI of 33.8 ± 4.4 kg/m2. Average weight loss achieved in the CR versus NoCR group was -8.3 ± 5.9% versus -1.1 ± 3.8%; p < .01. No main effect of CR was observed on the likelihood of achieving a clinically meaningful gait speed improvement (risk ratio [RR]: 1.09 [95% CI: 0.93, 1.27]) or gait speed decrement (RR: 0.77 [95% CI: 0.57, 1.04]). Interaction effects were nonsignificant across all subgroups.Conclusion: The proportion of individuals experiencing a clinically meaningful gait speed change was similar for CR and NoCR conditions. This finding is consistent across several baseline subgroupings. [ABSTRACT FROM AUTHOR]

Background: Higher energetic costs for mobility are associated with declining gait speed, and slow gait is linked to cognitive decline and Alzheimer's disease. However, the physiological underpinnings of gait and brain health have not been well explored. We examined the associations of the energetic cost of walking with brain volume in cognitively unimpaired adults from the Baltimore Longitudinal Study of Aging.Methods: We used brain magnetic resonance imaging (MRI) data from 850 participants (mean baseline age 66.3 ± 14.5 years), of whom 451 had longitudinal MRI data (2.8 ± 1.0 MRI scans over 4.0 ± 2.0 years). The energetic cost of walking was assessed as the average energy expended (V̇O2) during 2.5 minutes of customary-paced overground walking. Multivariable linear mixed-effects models examined the associations between baseline energetic cost of walking and regional brain volumes adjusting for covariates.Results: At baseline, higher energetic cost of walking was cross-sectionally associated with lower gray and white matter volumes within the frontal, parietal, and temporal lobes, as well as hippocampal, total brain, and larger ventricular volumes (all false-discovery rate [FDR] p < .05). A baseline energetic cost of walking × time interaction demonstrated that participants with higher energetic cost of walking had faster annual decline in hippocampal volume (FDR p = .02) and accelerated annual increase in ventricular volumes (FDR p = .02).Conclusions: The energetic cost of walking is associated with gray and white matter volumes and subsequent hippocampal atrophy and ventricular enlargement. Collectively, these data suggest the energetic cost of walking may be an early marker of neurodegeneration that contributes to the gait brain connection. [ABSTRACT FROM AUTHOR]

Background: Cognitive reserve (CR) protects against cognitive decline, but whether CR influences the efficiency of cortical control of gait has not been reported. The current study addressed this important gap in the literature. Specifically, we determined the role of CR in moderating the efficiency of functional near-infrared spectroscopy (fNIRS)-derived oxygenated hemoglobin (HbO2) in the prefrontal cortex (PFC) assessed during active walking. We hypothesized that higher CR would be associated with more efficient brain activation patterns.Methods: Participants were 55 (mean age = 74.84; %female = 49.1) older adults who underwent the combined walking/fNIRS protocol and had magnetic resonance imaging data. We used an established dual-task walking paradigm that consisted of 3 task conditions: single-task walk (STW), single-task alpha (STA, cognitive task), and dual-task walk (DTW). Using the residual approach, CR was derived from a word-reading test score by removing variance accounted for by sociodemographic variables, tests of current cognitive functions, and a measure of structural brain integrity.Results: CR moderated the change in fNIRS-derived HbO2 in the PFC across tasks. Higher CR was associated with smaller increases in fNIRS-derived HbO2 from the single tasks to dual-task walking (CR × DTW compared with STW: estimate = 0.183; p < .001; CR × DTW compared with STA: estimate = 0.257; p < .001). The moderation effect of CR remained significant when adjusting for multiple covariates and concurrent moderation effects of measures of gait performance, current cognitive functions, and structural integrity of the brain.Conclusion: The current study provided first evidence that higher CR was associated with better neural efficiency of walking in older adults. [ABSTRACT FROM AUTHOR]

Background: Substantive previous work has shown that both gait speed and global cognition decline as people age. Rates of their decline, as opposed to cross-sectional measurements, could be more informative of future functional status and other clinical outcomes because they more accurately represent deteriorating systems. Additionally, understanding the sex and racial disparity in the speed of deterioration, if any, is also important as ethnic minorities are at an increased risk of mobility disability and dementia.Method: Data from 2 large longitudinal intervention studies were integrated. Rates of decline were derived from individual-level measures of gait speed of 400-m walk and scores on the Modified Mini Mental State Examination (3MSE). We also assessed age-associated declines and accelerations in changes across the ages represented in the studies (age range 53-90).Results: The mean rate of decline in 400-m gait speed across individuals was 0.03 m/s per year, and multivariable analysis showed a significant acceleration in decline of -0.0013 m/s/y2 (p < .001). Both race and sex moderated the rate of decline. For global cognition, the mean rate of decline was 0.05 of a point per year on the 3MSE scale, and acceleration in the rate of decline was significant (-0.017 point/y2, p < .001), but neither sex nor race moderated the decline.Conclusion: Rate of decline in physical but not cognitive function appears moderated by sex and race. This finding, as well as rates and accelerations of decline estimated herein, could inform future intervention studies.Clinical Trials Registration Number: NCT00017953 (Look AHEAD); NCT01410097 (Look AHEAD ancillary); NCT00116194 (LIFE). [ABSTRACT FROM AUTHOR]

Background: Motor function affects ability to perform daily activities and maintain independence. Yet, the interrelatedness of upper and lower extremity motor impairments and the magnitude of their contribution to slow gait and mobility difficulty are not well investigated.Methods: Participants in the Baltimore Longitudinal Study of Aging (N = 728, aged 50-99) completed motor and physical function tests including grip and knee extension strength, pegboard, finger tapping, standing balance, chair stands, fast-paced 400-m walk, and usual gait speed. Slow gait was defined as usual gait speed <1.0 m/s. Mobility difficulty was defined as self-reported difficulty walking ¼ mile or climbing stairs. Structural equation modeling examined the interrelationships of motor measures and their contributions to slow gait and mobility difficulty, adjusting for demographics and comorbidities.Results: Poorer manual dexterity (-0.571 standard deviation [SD] units, p < .001) and lower muscle strength (upper and lower extremity; -0.447 SD units, p = .014) were most strongly associated with slow gait speed, followed by slower chair stand pace (-0.195 SD units, p = .002) and greater lap time variation (0.102 SD units, p = .028). Lower muscle strength (-0.582 SD units, p = .001) was most strongly associated with mobility difficulty, followed by slower chair stand pace (-0.322 SD units, p < .001), slower gait speed (-0.247 SD units, p < .001), and poorer standing balance (-0.190 SD units, p = .043).Conclusions: Components of manual dexterity and strength were the strongest correlates of slow gait and mobility difficulty in mid-to-late life. Longitudinal studies examining relationships between changes in these motor parameters and mobility are needed to elucidate possible causal effects. [ABSTRACT FROM AUTHOR]

Background: Neurogenic claudication (NC) is a debilitating spinal condition affecting older adults' mobility and quality of life.Methods: A randomized controlled trial of 438 participants evaluated the effectiveness of a physical and psychological group intervention (BOOST program) compared to physiotherapy assessment and tailored advice (best practice advice [BPA]) for older adults with NC. Participants were identified from spinal clinics (community and secondary care) and general practice records and randomized 2:1 to the BOOST program or BPA. The primary outcome was the Oswestry Disability Index (ODI) at 12 months. Data were also collected at 6 months. Other outcomes included ODI walking item, 6-minute walk test (6MWT), and falls. The primary analysis was intention-to-treat.Results: The average age of participants was 74.9 years (standard deviation [SD] 6.0) and 57% (246/435) were female. There was no significant difference in ODI scores between treatment groups at 12 months (adjusted mean difference [MD]: -1.4 [95% confidence intervals (CI) -4.03, 1.17]), but, at 6 months, ODI scores favored the BOOST program (adjusted MD: -3.7 [95% CI -6.27, -1.06]). At 12 months, the BOOST program resulted in greater improvements in walking capacity (6MWT MD: 21.7m [95% CI 5.96, 37.38]) and ODI walking item (MD: -0.2 [95% CI -0.45, -0.01]) and reduced falls risk (odds ratio: 0.6 [95% CI 0.40, 0.98]) compared to BPA. No serious adverse events were related to either treatment.Conclusions: The BOOST program substantially improved mobility for older adults with NC. Future iterations of the program will consider ways to improve long-term pain-related disability. Clinical Trials Registration Number: ISRCTN12698674. [ABSTRACT FROM AUTHOR]

Background: Gait and cognition decline with advancing age, and presage the onset of dementia. Yet, the relative trajectories of gait and cognitive decline in aging are poorly understood-particularly among those with the motoric cognitive risk (MCR) syndrome. This study compared changes in simple and complex gait performance and cognition, as a function of age and MCR.Methods: We examined gait and cognitive functions of 1 095 LonGenity study participants (mean age = 75.4 ± 6.7 years) with up to 12 years of annual follow-up. Participants were of Ashkenazi Jewish descent, free of dementia, ambulatory, and had a 12.2% MCR prevalence at baseline. Gait speed was measured at usual pace walking (single-task walking, STW-speed) and walking while talking (WWT-speed). Eleven neuropsychological test scores were examined separately, and as a global cognition composite. Linear mixed-effects models adjusted for baseline sex, education, parental longevity, cognitive impairment, and global health were used to estimate changes in gait and cognition, as a function of age and MCR.Results: STW-speed, WWT-speed, and cognitive tests performance declined in a nonlinear (accelerating) fashion with age. STW-speed declined faster than WWT-speed and cognitive test scores. People with MCR showed faster rates of decline on figure copy and phonemic fluency.Conclusions: Gait declines at a faster rate than cognition in aging. People with MCR are susceptible to faster decline in visuospatial, executive, and language functions. This study adds important knowledge of trajectories of gait and cognitive decline in aging, and identifies MCR as a risk factor for accelerated cognitive decline. [ABSTRACT FROM AUTHOR]

Background: To investigate changes in gait performance over time and how these changes are associated with the decline in structural network efficiency and cognition in older patients with cerebral small vessel disease (SVD).Methods: In a prospective, single-center cohort with 217 older participants with SVD, we performed 1.5T MRI scans, cognitive tests, and gait assessments evaluated by Timed UP and Go (TUG) test twice over 4 years. We reconstructed the white matter network for each subject based on diffusion tensor imaging tractography, followed by graph-theoretical analyses to compute the global efficiency. Conventional MRI markers for SVD, that is, white matter hyperintensity (WMH) volume, number of lacunes, and microbleeds, were assessed.Results: Baseline global efficiency was not related to changes in gait performance, while decline in global efficiency over time was significantly associated with gait decline (ie, increase in TUG time), independent of conventional MRI markers for SVD. Neither baseline cognitive performance nor cognitive decline was associated with gait decline.Conclusions: We found that disruption of the white matter structural network was associated with gait decline over time, while the effect of cognitive decline was not. This suggests that structural network disruption has an important role in explaining the pathophysiology of gait decline in older patients with SVD, independent of cognitive decline. [ABSTRACT FROM AUTHOR]

Gait initiation is a daily challenge even for healthy individuals as it requires the timely coupling between the automatic anticipatory postural adjustment (APA) and the voluntary step according to the context. Modulation of this motor event has been thought to involve higher level brain control, including cognitive inhibitory circuitries. Despite the known participation of the supplementary motor area (SMA) in the modulation of some parameters of APA, the participation of areas controlling inhibition during gait initiation still needs to be investigated. In this study, the hemodynamic responses of the SMA and dorsolateral prefrontal cortex (DLPFC) were assessed using functional near-infrared spectroscopy (fNIRS) during a gait initiation task under cognitive conflict to select the foot to step (congruent [CON] and incongruent [INC] conditions). The older group (OG) showed worse inhibitory control than the young group (YG) along with more impairments in APA parameters. OG also had a lower amplitude of hemodynamic responses in both areas than YG in the INC. The INC increased the correlation between SMA and DLPFC only in the YG. Aging seems to impair the interaction between the hemodynamic responses of SMA and DLPFC, which influences APA performance in gait initiation under cognitive conflict. [ABSTRACT FROM AUTHOR]

Background: Deficits in visual-somatosensory (VS) integration are linked to poor mobility. Given that sensory, motor, and cognitive processes rely on overlapping neural circuitry that are compromised in dementia and pre-dementia stages like mild cognitive impairment (MCI), we hypothesize that cognitive impairment will be associated with reduced VS integration, which will, in turn, impact the relation between VS integration and mobility.Methods: A total of 345 older adults (mean age 76.88 ± 6.45 years; 52% female) participated in the current study. Cognitive impairment was defined as presence of MCI or dementia. Magnitude of VS integration was quantified using probability models. All participants completed assessments of general cognition (Repeatable Battery for the Assessment of Neuropsychological Status; RBANS), quantitative gait, and balance (unipedal stance).Results: The magnitude of VS integration was lower in the 40 individuals with MCI (p = .02) and 12 with dementia (p = .04), relative to the 293 individuals without cognitive impairment. In fully adjusted models, magnitude of VS integration was only a strong predictor of performance on attention-based tests of the RBANS (β = 0.161; p < .01), regardless of cognitive status. Results from mediation analyses, however, reveal that cognitive impairment causes variation in magnitude of VS integration, which in turn causes variation in unipedal stance 95% confidence interval (CI) (-0.265, -0.002) and spatial aspects of gait 95% CI (-0.087, -0.001).Conclusions: Cognitive impairment influences multisensory integration, which adversely impacts balance and gait performance in aging. Future studies should aim to uncover the precise neural circuitry involved in multisensory, cognitive, and mobility processes. [ABSTRACT FROM AUTHOR]

Background: Growth and differentiation factor 15 (GDF-15) has been associated with obesity, muscle wasting, and cachexia. The receptor for GDF-15 was recently identified in the brainstem and regulates food intake and metabolism. The relationship of plasma GDF-15 with the age-associated decline of muscle mass and strength, gait speed, and physical performance in adults has not been well characterized.Methods: Plasma GDF-15, grip strength, 6-m gait speed, 400-m walking test time, lower extremity physical performance score, appendicular lean mass, and fat mass were measured in 194 healthy adult participants, aged 22-93 years, of the Baltimore Longitudinal Study of Aging.Results: Plasma GDF-15 concentrations increased with age (p < .001) and were higher in whites compared with blacks and Asians (p = .04). Adults with higher plasma GDF-15 had slower 6-m gait speed, longer 400-m walking time, and lower physical performance score in multivariable analyses adjusting for age and race. Plasma GDF-15 was not associated with grip strength, appendicular lean mass, or fat mass.Conclusions: Elevated plasma GDF-15 is associated with slower gait speed, higher 400-m walking time, and lower physical performance in very healthy community-dwelling adults. The relationship between plasma GDF-15 and sarcopenia-related outcomes may be stronger in the population not selected to be healthy, and this hypothesis should be tested in a representative population. [ABSTRACT FROM AUTHOR]

Background: The Short Physical Performance Battery (SPPB) is advocated as a screening tool in geriatric care for predicting future disability. We aimed to identify the leg neuromuscular attributes to be targeted in rehabilitative care among older adults with poor SPPB scores.Methods: Boston Rehabilitative Impairment Study of the Elderly (Boston RISE) participants (n = 430) underwent assessment of neuromuscular attributes (leg strength, leg velocity, trunk extensor endurance, knee flexion range of motion [ROM], ankle ROM, and foot sensation). Linear regression models examined association between each neuromuscular attribute and SPPB, adjusting for age, race, gender, comorbidity, body mass index, depression, cognition, and other neuromuscular attributes.Results: Participants with 1 SD unit higher leg strength, leg velocity, and trunk extensor endurance had 0.52, 0.30, and 0.52 points higher SPPB total score. Participants with ankle ROM impairment and foot sensory loss had 0.43 and 0.57 lower SPPB total score compared with those without these. Leg strength and trunk extensor endurance were associated with balance; leg velocity, trunk extensor endurance, and ankle ROM were associated with gait speed; and strength, trunk extensor endurance, knee ROM, and feet sensation were associated with chair stand score. Neuromuscular attributes, along with covariates, explained 40.4% of the variance in the total SPPB score, a substantial increase over the 22.7% variance explained by covariates alone.Conclusions: Neuromuscular attributes affect mobility performance in older patients as measured by the SPPB. Specific impairments are associated with poor performance in specific component scores. Assessment of the SPPB components and rehabilitation of associated impairments may help improve the functional performance among older adults. [ABSTRACT FROM AUTHOR]

Using multimodal neuroimaging methods, the current study was designed to examine the relationship between white matter microstructural integrity (WMI) and changes in prefrontal cortex (PFC) oxygenated hemoglobin (HbO2) during active walking in older adults. Consistent with neural inefficiency, we hypothesized that worse WMI would be associated with a greater increase in PFC HbO2 from single to dual-task walking in the context of worse or similar gait performance. Fifty-five cognitively healthy older adults (mean age = 74.76 years, 49% women) underwent diffusion tensor imaging (DTI) to derive a whole-brain measure of fractional anisotropy (FA) and functional Near Infrared Spectroscopy (fNIRS), which measured PFC HbO2 during walking tasks. Gait velocity was assessed using an instrumented walkway. A linear mixed effects model revealed that HbO2 levels increased from single to dual-task walking (P < 0.01) given the greater cognitive demands inherent in the latter condition. Moreover, WMI moderated the effect of dual tasking on PFC HbO2 (P < 0.05). Specifically, worse WMI was associated with a larger increase in PFC HbO2 levels from single to dual-task walking in the context of similar gait velocity. Results suggest that compromised WMI may be a mechanism underlying inefficient brain response to cognitive demands of locomotion. [ABSTRACT FROM AUTHOR]

Background: Subtle, but observable, changes in mobility often exist among older adults with mild cognitive impairment (MCI). Notably, these changes are not inconsequential. Therefore, there is a strong interest to better understand the underlying neural correlates of gait slowing among older adults with MCI. In this study, we aimed to characterize patterns of functional connectivity associated with slower gait speed in older adults with MCI.Methods: Forty-nine participants aged 60 years and older with MCI were included in the cross-sectional study. All participants underwent assessments of gait speed and resting state functional magnetic resonance imaging.Results: In this sample of older adults with MCI, slower usual gait was characterized by altered connectivity between the sensorimotor network (SMN) and the frontoparietal network (FPN) (p < .05)-specifically, slower usual gait was associated with greater connectivity between the supplementary motor area (SMA) and the bilateral ventral visual cortices (p = .01); lower connectivity between the SMA and the bilateral superior lateral occipital cortex (p < .01); and lower connectivity between the SMA and the bilateral frontal eye field (p < .01).Conclusion: Altered inter-network functional connectivity between the SMN and FPN may be a neural mechanism for slowing of gait in older adults with MCI. [ABSTRACT FROM AUTHOR]

Background: Falls are associated with gait impairments in older adults (OA) and Parkinson's disease (PD). Current approaches for evaluating falls risk are based on self-report or one-time assessment and may be suboptimal. Wearable technology allows gait to be measured continuously in free-living conditions. The aim of this study was to explore generic and specific associations in free-living gait in fallers and nonfallers with and without PD.Methods: Two hundred and seventy-seven fallers (155 PD, 122 OA) who fell twice or more in the previous 6 months and 65 nonfallers (15 PD, 50 OA) were tested. Free-living gait was characterized as the volume, pattern, and variability of ambulatory bouts (Macro), and 14 discrete gait characteristics (Micro). Macro and Micro variables were quantified from free-living data collected using an accelerometer positioned on the low back for one week.Results: Macro variables showed that fallers walked with shorter and less variable ambulatory bouts than nonfallers, independent of pathology. Micro variables within ambulatory bouts showed fallers walked with slower, shorter and less variable steps than nonfallers. Significant interactions showed disease specific differences in variability with PD fallers demonstrating greater variability (step length) and OA fallers less variability (step velocity) than their nonfaller counterparts (p < 0.004).Conclusions: Common and disease-specific changes in free-living Macro and Micro gait highlight generic and selective targets for intervention depending on type of faller (OA-PD). Our findings support free-living monitoring to enhance assessment. Future work is needed to confirm the optimal battery of measures, sensitivity to change and value for fall prediction. [ABSTRACT FROM AUTHOR]

Background: The longitudinal association between cerebral amyloid-beta (Aβ) and change in gait, and whether this association is mediated by cortical thickness, has yet to be determined.Methods: We included 439 clinically normal (CN) participants, aged 50-69 years and enrolled in the Mayo Clinic Study of Aging with cerebral Aβ, cortical thickness, and gait measurements. Cerebral Aβ deposition was assessed by Pittsburgh Compound B (PiB)-PET in multiple regions of interest (ROIs) (ie, frontal, orbitofrontal, parietal, temporal, anterior cingulate, posterior cingulate/precuneus, and motor). Cortical thickness was assessed on 3T MRI in corresponding ROIs. Gait parameters (gait speed, cadence, stride length, double support time, and covariance of stance time) were measured with GAITRite. Multivariate-adjusted two level structural equation models were used to examine the longitudinal association between PiB-PET, cortical thickness, and change in gait over a median 15.6 months.Results: Higher PiB-PET in all ROIs was associated with decreasing cadence and increasing double support time, and in the temporal ROI was associated with declining gait speed. In sex-stratified analyses, higher PiB-PET in all ROIs was associated with declining performance on all gait parameters among women. In contrast, among men, the only association was with higher orbitofrontal ROI PiB-PET and declining cadence. None of the associations were mediated by cortical thickness or attenuated after adjustment of baseline cognition.Conclusion: Higher PiB-PET was associated with declining gait, particularly among women in this middle-aged CN cohort, independent of cortical thickness and baseline cognitive. Elevated brain Aβ may play a critical role in age-related mobility decline. [ABSTRACT FROM AUTHOR]

Background: A growing number of studies are using modified treadmills to train reactive balance after trip-like perturbations that require multiple steps to recover balance. The goal of this study was thus to develop and validate a low-tech reactive balance rating method in the context of trip-like treadmill perturbations to facilitate the implementation of this training outside the research setting.Methods: Thirty-five residents of five senior congregate housing facilities participated in the study. Participants completed a series of reactive balance tests on a modified treadmill from which the reactive balance rating was determined, along with a battery of standard clinical balance and mobility tests that predict fall risk. We investigated the strength of correlation between the reactive balance rating and reactive balance kinematics. We compared the strength of correlation between the reactive balance rating and clinical tests predictive of fall risk with the strength of correlation between reactive balance kinematics and the same clinical tests. We also compared the reactive balance rating between participants predicted to be at a high or low risk of falling.Results: The reactive balance rating was correlated with reactive balance kinematics (Spearman's rho squared = .04-.30), exhibited stronger correlations with clinical tests than most kinematic measures (Spearman's rho squared = .00-.23), and was 42%-60% lower among participants predicted to be at a high risk for falling.Conclusion: The reactive balance rating method may provide a low-tech, valid measure of reactive balance kinematics, and an indicator of fall risk, after trip-like postural perturbations. [ABSTRACT FROM AUTHOR]

Background: This study evaluated whether baseline results of the Timed Up and Go (TUG) test is associated with future dementia occurrence.Methods: Using the Korean National Health Insurance Service-National Health Screening Cohort database, we identified 49,283 subjects without a dementia diagnosis who participated in the National Screening Program for Transitional Ages at 66 years of age during 2007-2012. Gait impairment was defined as taking longer than 10 seconds to perform the TUG test. Dementia occurrence was defined by the first prescription for acetylcholinesterase inhibitors or N-Methyl-D-Aspartate receptor antagonist with an International Classification of Diseases 10th Revision (ICD-10) code for dementia (F00, F01, F02, F03, G30, F051, or G311) during 2007-2013. Cox proportional hazard regression models were used to assess the hazard ratios for dementia occurrence according to baseline TUG test results.Results: Mean follow-up period was 3.8 years. Incidence rates of dementia were 4.6 and 6.8 cases per 1,000 person-years in the normal and impaired TUG groups, respectively. The impaired TUG group showed a higher risk of total dementia incidence (adjusted hazard ratio [aHR], 1.34; 95% confidence interval [95% CI], 1.14-1.57). Subtype analysis showed that the impaired TUG group had a higher risk of Alzheimer's disease (aHR, 1.26; 95% CI, 1.06-1.51) and vascular dementia (aHR, 1.65; 95% CI, 1.19-2.30).Conclusions: The TUG test result was associated with future dementia occurrence. More vigilant follow-up and early intervention to prevent dementia would benefit elderly people with impaired TUG test result. [ABSTRACT FROM AUTHOR]

Background: The aim was to investigate the associations of sarcopenia as defined by European Working Group on Sarcopenia in Older People (EWGSOP) and Foundation for the National Institutes of Health (FNIH) Sarcopenia Project, and their underlying components, with the incidence of recurrent falling and fractures.Methods: In 498 older men and women (mean age = 75.2 [SD = 6.4]) from the Longitudinal Aging Study Amsterdam (LASA), the sarcopenia components lean mass (DXA), handgrip strength (handheld dynamometer), and gait speed were measured. Data on falls (3-year follow-up) and fractures (10-year follow-up) were collected. Cox regression analyses were performed, adjusting for age, sex, and total body fat.Results: Recurrent falling occurred in 130 persons and 60 persons experienced a fracture during follow-up. Participants who were identified as sarcopenic based on the FNIH definitions had a more than 2-fold increased risk to become a recurrent faller. There was no association between sarcopenia based on the EWGSOP definition and incidence of recurrent falling. When the sarcopenia components were examined individually, only a low grip strength was associated with incidence of recurrent falling, independent of a low lean mass or a slow gait speed. Sarcopenia according to both definitions was not associated with incident fractures, which may be caused by low statistical power.Conclusion: Sarcopenia according to the FNIH definitions, but not according to the EWGSOP definition was associated with recurrent falling. When examining the individual components, only a low grip strength was independently associated with recurrent falling. No associations between sarcopenia with incidence of fractures were found. [ABSTRACT FROM AUTHOR]

Background: Mental fatigue is a psychobiological state induced by sustained periods of demanding cognitive activity and is characterized by feelings of tiredness which are common in everyday life. Recently, it has been hypothesized that mental fatigue might have an impact on gait performance in old adults. Therefore, the effect of mental fatigue on gait performance under single- and dual-task conditions was investigated in young and old participants.Methods: Spatio-temporal gait parameters of 16 young and 16 old healthy participants were measured using a photoelectric system during single- and dual-task walking before and after a randomly assigned mental fatigue (performing a stop-signal task for 90 minutes) and control intervention (watching a video for 90 minutes), respectively. Changes in subjective fatigue, wakefulness, mood, arousal, and psychophysiological workload (heart rate variability indices) were assessed.Results: Psychometric measures indicated increased subjective fatigue and arousal as well as decreased mood and wakefulness after the mental fatigue task. Heart rate variability indices revealed a higher psychophysiological workload during the mental fatigue intervention in old compared to young participants. Gait measures (coefficient of variation of speed, stride length, and stance time) revealed impaired dual-task walking performance following the mental fatigue intervention only in old participants.Conclusion: Data indicate that mental fatigue, induced by sustained cognitive activity, can impair gait performance during dual-task walking in old adults. The susceptibility to mental fatigue could be a new intrinsic risk factor for falls in older people and should be taken into account when dual-task gait analyses are performed. [ABSTRACT FROM AUTHOR]

Background: Total daily physical activity is associated with a wide range of adverse health outcomes. We examined the extent to which quantitative measures of gait and balance abilities were associated with total daily physical activity, controlling for a variety of potential covariates.Methods: Participants (n = 608) were older adults participating in the Rush Memory and Aging Project, a community-based cohort study of aging. Objective measures of total daily physical activity were derived from a wearable device. Gait and balance abilities were objectively quantified using a body-fixed sensor. We also collected measures of other motor functions, cognitive and psychosocial factors, and chronic health. We employed linear regression models to identify facets of mobility significantly associated with total daily physical activity, and tested for independence of these associations when all significant covariates were considered together in a final model.Results: Three gait and balance measures were independently associated with total daily physical activity (p < .01), together accounting for approximately 16% of its variance. Other motor measures, cognitive and psychosocial factors, and chronic health accounted for 8.8%, 4.9%, and 6.4% of the variance, respectively, when considered in isolation. Considered together in a single model, all significant covariates accounted for approximately 21% of the variance in physical activity.Conclusions: Gait and balance measures from a body-fixed sensor are strongly associated with objectively measured total daily physical activity in older adults. However, given the importance of physical activity to many health outcomes, further work is needed to more completely characterize the factors that may influence physical activity. [ABSTRACT FROM AUTHOR]

Background: Data collected by wearable accelerometry devices can be used to identify periods of sustained harmonic walking. This report aims to establish whether the features of walking identified in the laboratory and free-living environments are associated with each other as well as measures of physical function, mobility, fatigability, and fitness.Methods: Fifty-one older adults (mean age 78.31) enrolled in the Developmental Epidemiologic Cohort Study were included in the analyses. The study included an "in-the-lab" component as well as 7 days of monitoring "in-the-wild" (free living). Participants were equipped with hip-worn Actigraph GT3X+ activity monitors, which collect raw accelerometry data. We applied a walking identification algorithm and defined features of walking, including participant-specific walking acceleration and cadence. The association between these walking features and physical function, mobility, fatigability, and fitness was quantified using linear regression analysis.Results: Acceleration and cadence estimated from "in-the-lab" and "in-the-wild" data were significantly associated with each other (p < .05). However, walking acceleration "in-the-lab" was on average 96% higher than "in-the-wild," whereas cadence "in-the-lab" was on average 20% higher than "in-the-wild." Acceleration and cadence were associated with measures of physical function, mobility, fatigability, and fitness (p < .05) in both "in-the-lab" and "in-the-wild" settings. In addition, "in-the-wild" daily walking time was associated with fitness (p < .05).Conclusions: The quantitative difference in proposed walking features indicates that participants may overperform when observed "in-the-lab." Also, proposed features of walking were significantly associated with measures of physical function, mobility, fatigability, and fitness, which provides evidence of convergent validity. [ABSTRACT FROM AUTHOR]

Background: Frailty is a prevalent geriatric condition associated with poor health outcomes. The pathogenesis of frailty is incompletely understood. We aimed to evaluate the relationship between cerebral small vessel disease (SVD) and frailty.Methods: People aged between 60 and 85 years were randomly selected from the electoral roll into the Tasmanian Study of Cognition and Gait. Participants completed standardized questionnaires regarding medical history and underwent objective sensorimotor, gait, and cognitive testing. These data were used to calculate a frailty index score. Magnetic resonance imaging was performed on all participants to measure SVD. Automated quantification was used to measure white matter hyperintensities (WMH), with manual consensus for subcortical infarction (SI) and cerebral microbleeds (CMB). Multivariable linear regression was used to determine the association between SVD and frailty.Results: The mean age of the sample (n = 388) was 72.0 years (SD 7.0), 44% (172/388) were female and the median Frailty Index was 0.20 (interquartile range 0.12, 0.27). WMH, SI, and CMB in unadjusted models were positively associated with higher frailty scores (p < .05). In final models including all brain variables, higher burden of WMH (β = 2.16; 95% confidence interval [CI] 0.75, 3.57; p = .003), but not SI (β = 2.96; 95% CI -0.44, 6.35; p = .09) or CMB (β = -0.46; 95% CI -4.88, 3.96; p = .84), was independently associated with a higher frailty score.Conclusions: We provide cross-sectional evidence for a positive association between larger burden of WMH and frailty. Longitudinal design is required to determine the temporality of this relationship. [ABSTRACT FROM AUTHOR]

Background: Multimorbidity is an important health outcome but is difficult to quantify. We recently developed a multimorbidity-weighted index (MWI) and herein assess its performance in an independent nationally-representative cohort.Methods: Health and Retirement Study (HRS) participants completed an interview on physician-diagnosed chronic conditions and physical functioning. We determined the relationship of chronic conditions on physical functioning and validated these weights with the original, independently-derived MWI. We then determined the association between MWI with physical functioning, grip strength, gait speed, basic and instrumental activities of daily living (ADL/IADL) limitations, and the modified Telephone Interview for Cognitive Status (TICS-m) in adjusted models.Results: Among 20,509 adults, associations between chronic conditions and physical functioning varied several-fold. MWI values based on weightings in the HRS and original cohorts correlated strongly (Pearson's r = .92) and had high classification agreement (κ statistic = .80, p < .0001). Participants in the highest versus lowest MWI quartiles had weaker grip strength (-2.91 kg, 95% confidence interval [CI]: -3.51, -2.30), slower gait speed (-0.29 m/s, 95% CI: -0.35, -0.23), more ADL (0.79, 95% CI: 0.71, 0.87) and IADL (0.49, 95% CI: 0.44, 0.55) limitations, and lower TICS-m (-0.59, 95% CI: -0.77, -0.41) (all p < .001). We observed monotonic graded relationships for all outcomes with increasing MWI quartiles.Conclusion: A multimorbidity index weighted to physical functioning performed nearly identically in a nationally-representative cohort as it did in its development cohorts, confirming broad generalizability. MWI was strongly associated with subjective and objective physical and cognitive performance. Thus, MWI serves as a valid patient-centered measure of multimorbidity, an important construct in research and clinical practice. [ABSTRACT FROM AUTHOR]

Background: The apolipoprotein E polymorphism ε4 allele (ApoE4) and gait impairment are both known risk factors for developing cognitive decline and dementia. However, it is unclear the interrelationship between these factors, particularly among older adults with mild cognitive impairment (MCI) who are considered as prodromal for Alzheimer's disease. This study aimed to determine whether ApoE4 carrier individuals with MCI may experience greater impairment in gait performance.Methods: Fifty-six older adults with MCI from the "Gait and Brain Study" who were identified as either ApoE4 carriers (n = 20) or non-ApoE4 carriers (n = 36) with 1 year of follow-up were included. Gait variability, the main outcome variable, was assessed as stride time variability with an electronic walkway. Additional gait variables and cognitive performance (mini-mental state examination [MMSE] and Montreal Cognitive Assessment [MoCA]) were also recorded. Covariates included age, sex, education level, body mass index, and number of comorbidities.Results: Baseline characteristics were similar for both groups. Repeated measures analysis of covariance showed that gait stride time and stride length variabilities significantly increased in ApoE4 carriers but was maintained in the non-ApoE4 carriers. Similarly, ApoE4 carriers showed greater decrease in MMSE score at follow-up.Conclusions: In this sample of older adults with MCI, the presence of at least one copy of ApoE4 was associated with the development of both increased gait variability and cognitive decline during 1 year of follow-up. ApoE4 genotype might be considered as a potential mediator of decline in mobility function in MCI; future studies with larger samples are needed to confirm our preliminary findings. [ABSTRACT FROM AUTHOR]

Background: The relationship between measures of visual function and gait related risk factors for falls is unclear. In this study, we examine the relationship between visual function (visual acuity [VA] and contrast sensitivity [CS] at multiple spatial frequencies) and quantitative spatiotemporal gait, using a large, nationally representative sample of community dwelling older adults.Methods: Participants aged 50 and over were recruited as part of The Irish Longitudinal Study on Ageing (TILDA). VA was measured with the LogMAR chart according to the Early Treatment of Diabetic Retinopathy Study protocol. CS was measured at five spatial frequencies ranging 1.5 to 18 cycles per degree (cpd) using the Functional Acuity Contrast Test. Gait speed, cadence, and stride length were measured using the GAITRite system. Multivariate analysis examined associations between gait and visual performance parameters adjusting for socioeconomic, physical, cognitive, and mental health covariates.Results: Data from 4,678 participants were analyzed (age 61.7 ± 8.3 years, 54.1% woman). Poorer CS at 1.5 cpd and 3.0 cpd (low spatial frequency) was independently associated with decreased stride length (CS at 1.5 cpd: β = .031; p = .001 and CS at 3.0 cpd: β = .020; p = .001) but not cadence or gait speed. There was no evidence of an association between VA and any of the gait variables considered (p > .05).Conclusion: Reduced CS, at low spatial frequencies, is independently associated with shorter stride length, while VA is not associated with any gait measures. This evidence suggests that it may be necessary to consider refocus of the assessment of vision to include the most appropriate measures. [ABSTRACT FROM AUTHOR]

Background: Musculoskeletal pain is highly prevalent and limits mobility in older adults. A potential mechanism by which pain affects mobility could be through its negative impact on the brain. We examined whether structural integrity of cerebral gray and white matter (WM) mediated the relationship between pain and mobility in community-dwelling older adults.Methods: Musculoskeletal pain, gait speed, and neuroimaging data were obtained concurrently from the Health ABC study (mean age = 83/56% female, n = 212). Microstructural gray matter integrity was measured by mean diffusivity (MD), WM microstructure and macrostructure were measured by fractional anisotropy (FA) and WM hyperintensities (WMH), respectively. Regression models were adjusted for gray matter atrophy, age, gender, medication use, and obesity. Bootstrapped mediation methods were used (1,000 bootstrapped samples, 95% confidence intervals).Results: The associations of musculoskeletal pain with WMH (β = .19, p < .05) and FA (β = -.18, p < .05) were robust to adjustment for gender, medication use, age, body mass index (BMI), and brain atrophy. Participants who experienced both knee and back pain had a significantly slower gait speed (~0.11 m/s) than those without knee or back pain (p < .05) independent of gender, medication, age, and BMI. WMH and FA significantly mediated the pain-gait speed relationship. Associations between pain and MD were not significant, and MD did not modify the association between pain and gait speed.Conclusions: Cerebral WM integrity may contribute to the detrimental effects of musculoskeletal pain on mobility, although pre-existing WM integrity may also simultaneously amplify pain and decrease mobility. Future studies are needed to further understand whether successful pain management may significantly improve both brain health and mobility. [ABSTRACT FROM AUTHOR]

Background: The ability to adapt gait when negotiating unexpected hazards is crucial to maintain stability and avoid falling. This study investigated whether impaired gait adaptability in a task including obstacle and stepping targets is associated with cognitive and sensorimotor capacities in older adults.Methods: Fifty healthy older adults (74±7 years) were instructed to either (a) avoid an obstacle at usual step distance or (b) step onto a target at either a short or long step distance projected on a walkway two heel strikes ahead and then continue walking. Participants also completed cognitive and sensorimotor function assessments.Results: Stroop test and reaction time performance significantly discriminated between participants who did and did not make stepping errors, and poorer Trail-Making test performance predicted shorter penultimate step length in the obstacle avoidance condition. Slower reaction time predicted poorer stepping accuracy; increased postural sway, weaker quadriceps strength, and poorer Stroop and Trail-Making test performances predicted increased number of steps taken to approach the target/obstacle and shorter step length; and increased postural sway and higher concern about falling predicted slower step velocity.Conclusions: Superior executive function, fast processing speed, and good muscle strength and balance were all associated with successful gait adaptability. Processing speed appears particularly important for precise foot placements; cognitive capacity for step length adjustments; and early and/or additional cognitive processing involving the inhibition of a stepping pattern for obstacle avoidance. This information may facilitate fall risk assessments and fall prevention strategies. [ABSTRACT FROM AUTHOR]

Background: Age-related mobility limitations are debilitating and common. Cerebral white matter hyperintensities (WMH) and conditions affecting other systems are known contributors, but have been studied in isolation.Methods: In 2,703 adults aged 65 years or older, we assessed cross-sectional and longitudinal gait speed and mobility disability (self-reported difficulty walking half mile) in those with and without high burden of MRI-defined WMH along with six other conditions (OCs) affecting mobility: gender-specific weak grip; poor self-reported vision; gender-specific lowest quartile of forced vital capacity; self-reported joint pain; ankle-arm index less than 0.9; and body mass index (BMI) greater than 30 kg/m2. Separate regression models adjusted for age, gender, and race were repeated for each OC and based on a 4-level predictor: -WMH/-OC; -WMH/+OC; +WMH/-OC; and +WMH/+OC.Results: Gait speed was fastest in those with -WMH/-OC and slowest for those with +WMH/+OC. Gait speed was similar for either WMH or one of the OC (p range: .07-.9), except for BMI. Those with a high BMI had slower gait speed than those with WMH (p = .01). Declines in gait speed over 6 years were similar for all groups. Results for both prevalent and incident mobility disability showed that associations for WMH and OC were similar for weak grip, poor vision, and low forced vital capacity (p range: .1-.7). Having joint pain, low ankle-arm index, or high BMI was associated with higher prevalent and incident mobility disability compared with having WMH (p range: <.001-.02).Conclusions: Cerebral WMH should be considered along with conditions affecting mobility from other systems when considering risk and treatment for mobility limitations. [ABSTRACT FROM AUTHOR]

Background: Traumatic brain injury (TBI) has been identified as a risk factor for Parkinson's disease (PD). Motor dysfunction among TBI-exposed elders without PD has not been well characterized. We sought to determine whether remote TBI is a risk factor for motor dysfunction on exam and functionally relevant motor dysfunction in day-to-day life among independently living elders without PD.Methods: This is a cross-sectional cohort study of independently living retired military veterans aged 50 or older with (n = 78) and without (n = 85) prior TBI-all without diagnosed PD. To characterize multidimensional aspects of motor function on exam, the Unified Parkinson's Disease Rating Scale (UPDRS) Motor Examination was performed by a board-certified neurologist and used to calculate a modified UPDRS (mUPDRS) global motor score and four domain scores (tremor, rigidity, bradykinesia, and posture/gait). Functionally relevant motor dysfunction was assessed via self-report of falls within the past year.Results: In analyses adjusted for demographics and comorbidities that differed between groups, compared with veterans without TBI, those with moderate-to-severe TBI were more likely to have fallen in past year (33% vs. 14%, risk ratio 2.5 [95% confidence interval 1.1-5.4]), had higher (worse) mUPDRS global motor (p = .03) and posture/gait scores (p = .02), but not higher tremor (p = .70), rigidity (p = .21), or bradykinesia scores (p = .22). Mild TBI was not associated with worse motor function.Conclusions: Remote moderate-to-severe TBI is a risk factor for motor dysfunction-defined as recent falls and impaired posture/gait-among older veterans. TBI-exposed older adults may be ideal candidates for aggressive fall-screening and prevention strategies. [ABSTRACT FROM AUTHOR]

Background: People age differently, challenging the identification of those more at risk of rapid health deterioration. This study aimed to explore the heterogeneity in the health of older adults by using five clinical indicators to detect age-related variation and individual health trajectories over time.Methods: Health of 3,363 people aged 60+ from the Swedish National study on Aging and Care-Kungsholmen (SNAC-K) assessed at baseline and at 3- and 6-year follow-ups. Number of chronic diseases, physical and cognitive performance, personal and instrumental activities of daily living were integrated in a health assessment tool (HAT). Interindividual health differences at baseline and follow-ups were assessed with logistic quantile regression. Intraindividual health trajectories were traced with quantile mixed-effect models.Results: The HAT score ranges from 0 (poor health) to 10 (good health); each score corresponds to a specific clinical profile. HAT was reliable over time and accurately predicted adverse health outcomes (receiver-operating characteristic areas: hospitalization = 0.78; 95% confidence interval = 0.74-0.81; mortality = 0.85; 95% confidence interval = 0.83-0.87; similar areas obtained for gait speed). Before age 85, at least 90% of participants were free of severe disability, and at least 50% were functionally independent despite chronic disorders. Age- and sex-related variation and high heterogeneity in health were detected at baseline and confirmed by intraindividual health trajectories.Conclusions: This study provides a positive picture of the health status of people 60+. Despite the complexity and heterogeneity of health in this age group, we could identify age- and sex-specific health trajectories using an integrated HAT. HAT is potentially useful in clinical practice and public health interventions. [ABSTRACT FROM AUTHOR]

Background: Prior studies suggest being overweight may be protective against poor functional outcomes in older adults.Methods: Body mass index (BMI, kg/m2) was measured over 25 years across five visits (1987-2011) among Atherosclerosis Risk in Communities Study participants (baseline Visit 1 n = 15,720, aged 45-64 years). Gait speed was measured at Visit 5 ("late-life", aged ≥65 years, n = 6,229). BMI trajectories were examined using clinical cutpoints and continuous mixed models to estimate effects of patterns of BMI change on gait speed, adjusting for demographics and comorbidities.Results: Mid-life BMI (baseline visit; 55% women; 27% black) was associated with late-life gait speed 25 years later; gait speeds were 94.3, 89.6, and 82.1 cm/s for participants with baseline normal BMI (<25), overweight (25 ≤ BMI < 30), and obese (BMI ≥ 30) (p < .001). In longitudinal analyses, late-life gait speeds were 96.9, 88.8, and 81.3 cm/s for participants who maintained normal, overweight, and obese weight status, respectively, across 25 years (p < .01). Increasing BMI over 25 years was associated with poorer late-life gait speeds; a 1%/year BMI increase for a participant with a baseline BMI of 22.5 (final BMI 28.5) was associated with a 4.6-cm/s (95% confidence interval: -7.0, -1.8) slower late-life gait speed than a participant who maintained a baseline BMI of 22.5.Conclusion: Being overweight in older age was not protective of mobility function. Maintaining a normal BMI in mid- and late-life may help preserve late-life mobility. [ABSTRACT FROM AUTHOR]

Background: Type 2 diabetes mellitus may alter the effect of physical activity on physical and cognitive function.Methods: The Lifestyle Interventions and Independence for Elders (LIFE) trial randomized controlled clinical trial of physical activity intervention (walking, resistance training, and flexibility exercises) enrolled adults aged 70-89 years who were sedentary and non-demented and who had functional limitations. Standardized measures of physical and cognitive function were collected an average of 2 years post-randomization. Differences between the intervention and control groups from 415 individuals with diabetes and 1,061 individuals without diabetes were contrasted with analyses of covariance.Results: At 24 months, assignment to the physical activity intervention resulted in 0.019 m/s relatively faster average 400-meter gait speeds (p = .007 overall) both for individuals with and without diabetes (intervention × diabetes interaction p = .99). No benefits were seen on scores from a physical performance battery. Performance on cognitive tests was better among participants assigned to the physical activity intervention compared with control only for those with diabetes, particularly for global cognitive function (p = .02) and delayed memory (p = .005), with mean [95% confidence intervals] for benefit from physical activity intervention of 0.114 [0.007,0.111] and 0.208 [0.030,0.387] standard deviations, respectively.Conclusions: Physical activity intervention improved the gait speed of older, sedentary individuals with and without diabetes. The cognitive function benefits occurred among participants with, but not without, diabetes. The mechanisms through which physical activity affects physical and cognitive function in older adults may differ for individuals by diabetes status. [ABSTRACT FROM AUTHOR]

Background: Prospective studies in the general population show that slow gait speed is associated with cognitive decline and clinical progression to dementia. However, longitudinal studies in memory clinic populations are mostly lacking. We aimed to study the association between gait speed and grip strength and cognitive functioning at baseline and cognitive decline over time in memory clinic patients with subjective cognitive decline and mild cognitive impairment.Methods: We included 309 patients (age 70 ± 9 years, 108 [35%] women, Mini-Mental State Examination 27 ± 3 points). Baseline gait speed was assessed over 15 feet, grip strength with a hydraulic hand dynamometer. Cognitive functioning was assessed annually with a comprehensive test battery during 3 years.Results: Age- and gender-adjusted linear mixed models showed that slower gait speed was related to worse baseline attention, memory, information processing speed, and verbal fluency. Longitudinally, gait speed was related to decline in information processing speed and executive functioning. Weaker grip strength was related to worse baseline information processing speed and executive functioning but there were no longitudinal associations. Cox proportional hazards models revealed no significant associations with clinical progression.Conclusions: Our findings suggest that markers of physical performance are related to current cognitive status and modestly related to cognitive decline but are seemingly not useful as an early marker of incident clinical progression. [ABSTRACT FROM AUTHOR]

Background: Reaction time measures have considerable potential to aid neuropsychological assessment in a variety of health care settings. One such measure, the intraindividual reaction time variability (IIV), is of particular interest as it is thought to reflect neurobiological disturbance. IIV is associated with a variety of age-related neurological disorders, as well as gait impairment and future falls in older adults. However, although persons diagnosed with Mild Cognitive Impairment (MCI) are at high risk of falling, the association between IIV and prospective falls is unknown.Methods: We conducted a longitudinal cohort study in cognitively intact (n = 271) and MCI (n = 154) community-dwelling adults aged 70-90 years. IIV was assessed through a variety of measures including simple and choice hand reaction time and choice stepping reaction time tasks (CSRT), the latter administered as a single task and also with a secondary working memory task.Results: Logistic regression did not show an association between IIV on the hand-held tasks and falls. Greater IIV in both CSRT tasks, however, did significantly increase the risk of future falls. This effect was specific to the MCI group, with a stronger effect in persons exhibiting gait, posture, or physiological impairment.Conclusions: The findings suggest that increased stepping IIV may indicate compromised neural circuitry involved in executive function, gait, and posture in persons with MCI increasing their risk of falling. IIV measures have potential to assess neurobiological disturbance underlying physical and cognitive dysfunction in old age, and aid fall risk assessment and routine care in community and health care settings. [ABSTRACT FROM AUTHOR]

Background: We examined relationships between cerebral amyloid-beta (Aβ) and cognitive-gait dual-task performance in 27 cognitively normal, mobility unimpaired elders. Methods: We assessed Aβ on Pittsburgh Compound B (PiB)-PET. We measured gait speed separately and while performing working-memory, response-inhibition, motor-sequencing, and phone-dialing tasks. We compared dual-task costs on gait and cognitive performance in high-Aβ (PiB(+)) and low-Aβ (PiB(-)) groups and examined the association between Aβ and dual-task performance decrements. Results: PiB(+) (n = 16) were comparable with the PiB(-) (n = 11) individuals on demographics, general cognitive and physical performance, and key brain MRI characteristics. PiB(+) group demonstrated greater dual-task costs on gait speed on all cognitive tasks (p < .05) except on response inhibition. Dual-task costs on cognition were similar between groups. Overall, Aβ was associated with dual-task decrement on gait speed but not on dual-task decrement on cognitive performance. Conclusions: Preliminary evidence indicates that cerebral Aβ is associated with gait slowing on dual-tasking in healthy older adults. [ABSTRACT FROM AUTHOR]

Skeletal muscles contain a large volume of water that is classified into intracellular (ICW) and extracellular (ECW) water fractions. Nuclear magnetic resonance-based biomarkers suggest that increased water T2 heterogeneities, as well as elevated water T2 relaxation in the quadriceps occurs in the elderly when compared with young adults. However, nuclear magnetic resonance is difficult to apply to a large-scale study or a clinical setting for sarcopenia and frailty screening. Segmental bioelectrical impedance spectroscopy is a unique tool used to assess the segmental ratio of ECW/ICW in the limbs. We evaluated 405 community-living people aged between 65 and 90 years. ECW and ICW in the upper legs were assessed by segmental bioelectrical impedance spectroscopy. Isometric knee extension strength, gait speed, and skeletal muscle mass were measured. Thigh ECW/ICW was negatively correlated with knee extension strength and gait speed (r = -.617 and -.431, respectively, p < .001) and increased with age (p < .001). Thigh ECW/ICW was a significant predictor of knee extension strength and gait speed independent of age, sex, body mass index, and skeletal muscle mass. Relative expansion of ECW against ICW in the thigh muscles is a factor in decreased muscle quality and a biomarker of muscle aging. [ABSTRACT FROM AUTHOR]

Background: The present study aimed to (i) evaluate previous observations that the association of blood pressure (BP) with outcomes varies by gait speed and (ii) evaluate the association of subsequent changes in BP and cardiovascular risk.Methods: Participants included 2,669 adults aged 70-79 years in the Health, Aging, and Body Composition (Health ABC) study. Gait speed was dichotomized at ≥1.0 m/s over a 20-m test at baseline. BP was measured at baseline, and changes in BP over 5 years were evaluated using (i) population-based trajectory models and (ii) intraindividual mean and slope.Results: Over a mean of 10 years, there were 1,366 deaths, 336 first myocardial infarctions, and 295 first strokes. There was a differential pattern of association between baseline systolic BP and diastolic BP and outcomes among brisk and moderate speed walkers. For example, the association between higher diastolic BP and mortality was in the protective direction for moderate speed walkers (hazard ratio = 0.75; 95% confidence interval: 0.63, 0.91) per 10 mmHg higher, whereas it was null in brisk walkers (hazard ratio = 1.05; 95% confidence interval: 0.98, 1.11), p value for interaction .01. The 5-year population-based trajectories did not add important information beyond baseline BP. Individual slopes in both systolic BP and diastolic BP did not appear to have important associations with the outcomes.Conclusions: In this study, we found that the overall level of BP was associated with myocardial infarction, stroke, and death, and this association differed by baseline gait speed, whereas changes in BP were not associated with these outcomes. [ABSTRACT FROM AUTHOR]

Background: Few cohort studies have examined longitudinal associations between age-related changes in cognition and physical performance. Further, whether these associations differ for men versus women or can be attributed to differences in physical activity (PA) is unknown.Methods: Participants were 2,876 initially well-functioning community-dwelling older adults (aged 70-79 years at baseline; 52% female; 39% black) studied over a 9-year period. Usual gait speed, self-reported PA, and two cognitive measures-Digit Symbol Substitution Test (DSST) and Mini-Modified Mental State examination (3MS)-were assessed years 0 (ie, baseline), 4, and 9.Results: Early decline between years 0 and 4 in gait speed predicted later decline between years 4 and 9 in performance on the 3MS (β = 0.10, p = .004) and on the DSST (β = 0.16, p < .001). In contrast, the associations between early decline in cognition and later decline in gait speed were weaker and were non-significant after correcting for multiple comparisons (β = 0.08, p = .019 for 3MS and β = .06, p = .051 for DSST). All associations were similar for women and men and were unaltered when accounting for PA levels.Conclusions: The results indicate declining gait speed as a precursor to declining cognitive functioning, and suggest a weaker reciprocal process among older women and men. [ABSTRACT FROM AUTHOR]

Background: Cognitive-frailty, defined as the presence of both frailty and cognitive impairment, is proposed as a distinctive entity that predicts dementia. However, it remains controversial whether frailty alone, cognitive-frailty, or the combination of cognitive impairment and slow gait pose different risks of incident dementia.Methods: Two hundred and fifty-two older adults free of dementia at baseline (mean age 76.6±8.6 years) were followed up to 5 years with bi-annual visits including medical, cognitive, and gait assessments. Incident all-cause of dementia and cognitive decline were the main outcomes. Frailty was defined using validated phenotypic criteria. Cognition was assessed using the Montreal Cognitive Assessment while gait was assessed using an electronic walkway. Cox Proportional Hazards models were used to estimate the risk of cognitive decline and dementia for frailty, cognitive-frailty, and gait and cognition models.Results: Fifty-three participants experienced cognitive decline and 27 progressed to dementia (incident rate: 73/1,000 person-years). Frailty participants had a higher prevalence of cognitive impairment compared with those without frailty (77% vs. 54%, p = .02) but not significant risk to incident dementia. Cognitive-frailty increased incident rate (80/1,000 person-years) but not risk for progression to dementia. The combination of slow gait and cognitive impairment posed the highest risk for progression to dementia (hazard ratio: 35.9, 95% confidence interval: 4.0-319.2; p = 0.001, incident rate: 130/1,000 person-years). None of the models explored significantly predicted cognitive decline.Conclusions: Combining a simple motor test, such as gait velocity, with a reliable cognitive test like the Montreal Cognitive Assessment is superior than the cognitive-frailty construct to detect individuals at risk for dementia. Cognitive-frailty may embody two different manifestations, slow gait and low cognition, of a common underlying mechanism. [ABSTRACT FROM AUTHOR]

Background: Research suggests that the central nervous system (CNS) and mobility are closely linked. CNS-mediated mobility impairment may represent a potentially new and prevalent syndrome within the older adult populations. Interventions targeting this group may have the potential to improve mobility and cognition and prevent disability.Methods: In 2012, the Gerontological Society of America (GSA) and the National Institute on Aging (NIA) sponsored a 3-year conference workshop series, "Aging, the CNS, and Mobility." The goal of this third and final conference was to (i) report on the state of the science of interventions targeting CNS-mediated mobility impairment among community-dwelling older adults and (ii) partnering with the NIA, explore the future of research and intervention design focused on a potentially novel aging syndrome.Results: Evidence was presented in five main intervention areas: (i) pharmacology and diet; (ii) exercise; (iii) electrical stimulation; (iv) sensory stimulation/deprivation; and (v) a combined category of multimodal interventions. Workshop participants identified important gaps in knowledge and key recommendations for future interventions related to recruitment and sample selection, intervention design, and methods to measure effectiveness.Conclusions: In order to develop effective preventive interventions for this prevalent syndrome, multidisciplinary teams are essential particularly because of the complex nature of the syndrome. Additionally, integrating innovative methods into the design of interventions may help researchers better measure complex mechanisms, and finally, the value of understanding the link between the CNS and mobility should be conveyed to researchers across disciplines in order to incorporate cognitive and mobility measurements into study protocols. [ABSTRACT FROM AUTHOR]

Background: Difficulty turning is a major contributor to mobility disability, falls, and reduced quality of life in older people because it requires dynamic balance control that worsens with age. However, no study has quantified the quality and quantity of turning during normal daily activities in older people. The objective of this pilot study was to determine if quality of turning during daily activities is associated with falls and/or cognitive function.Methods: Thirty-five elderly participants (85 ± 8 years) wore three Opal inertial sensors. Turning and activity rate were measured. Based on retrospective falls, participants were grouped into nonfallers (N = 16), single fallers (N = 12), and recurrent fallers (N = 7). We also determined which turning characteristic predicted falls in the 6 months following the week of monitoring.Results: Quality of turning was significantly compromised in recurrent fallers compared with nonfallers (p < .05). In contrast, activity rate and mean number of turns per hour were similar across the three groups. Also, quality of turning during a prescribed test was similar across the three groups. Visuospatial and memory functions and the Tinetti Balance Scores were associated with quality of turning. Future falls were related to an increased variability of number of steps to turn.Conclusions: Continuous monitoring of turning characteristics, while walking during daily activities, is feasible in older people. Turning characteristics during daily life appear to be more sensitive to fall risk than prescribed turning tasks. These findings suggest a slower, less variable, cautious turning strategy in elderly volunteers with a history of falls. [ABSTRACT FROM AUTHOR]

Background: The "motoric cognitive risk" (MCR) syndrome is a newly reported predementia syndrome combining cognitive complaint and slow gait speed. We hypothesized that individuals with MCR syndrome would have lower brain volumes compared with non-MCR individuals. This study aims (i) to compare the cognitive profile of nondemented older community-dwellers with and without MCR syndrome and (ii) to examine association of global and regional brain volumes with MCR syndrome.Methods: A total of 171 individuals (28 MCR and 143 non-MCR) were included in this cross-sectional study. Total white matter abnormalities, total white matter, total cortical and subcortical gray matters, hippocampus, motor cortex, premotor cortex, and prefrontal cortex were examined. Brain volumes were quantified from a three-dimensional T1-weighted magnetic resonance imaging using semi-automated software. Age, gender, education level, number of drugs taken daily, use of psychoactive drugs, and cognitive profile were also measured.Results: The distribution of cognitively healthy individuals and those with mild cognitive impairment was not different in participants with and without MCR. Multiple logistic regression models showed that smaller volumes of total gray matter (p = .016), total cortical gray matter (p = .010), premotor cortex (p = .018), prefrontal cortex (p = .026), and dorsolateral segment of prefrontal cortex (p = .032) were associated with MCR status. The premotor cortex presented the highest mean difference for brain regional volume between MCR and non-MCR participants (p = .03).Conclusions: The findings revealed similar cognitive profile in MCR and non-MCR participants, and MCR-related smaller global and regional gray matter volumes involving premotor and prefrontal cortices, suggesting that the MCR syndrome may predict cortical neurodegenerative dementia more than subcortical dementia. [ABSTRACT FROM AUTHOR]

Background: White matter hyperintensities (WMH), a common marker of cerebral small vessel disease, and lower microstructural integrity of normal-appearing white matter are associated with slower gait. How these cerebral measures interact in relation to slower gait is unknown. We assessed whether microstructural integrity of normal-appearing white matter, measured by fractional anisotropy (FA), moderates the association of higher WMH with slower gait.Methods: WMH, FA, and gait speed were acquired for 265 community-dwelling older adults (average age = 82.9 years).Results: The inverse association between WMH and gait was robust to adjustment for age, gender, muscle strength, obesity, stroke, and hypertension (fully adjusted model: βs = -0.19, p = .001). The interaction between WMH and FA was significant; analyses stratified by FA showed that the inverse association between WMH and gait speed was significant only for those with low FA (FA < median, fully adjusted model: βs = -0.28, p = .001). Voxel-based results were similar for participants with FA less than median, there was an inverse association between gait speed and WMH which extended throughout the white matter (genu and body of corpus callosum, anterior limb of internal capsule, corona radiata, and superior longitudinal and fronto-occipital fasciculus). In contrast, for participants with FA ≥ median, the association was limited to the genu of corpus callosum, the cingulum, and the inferior longitudinal fasciculus.Conclusions: Microstructural integrity is a moderating factor in the association between WMH and gait. Future studies should examine whether higher microstructural integrity represents a source of compensation in those with greater WMH burden to maintain function in late life. [ABSTRACT FROM AUTHOR]