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Objective To investigate a proposed cognitively-mediated pathway whereby pain contributes to gait impairments by acting as a distractor in community-living older adults. Design A cross-sectional study of a population-based cohort of older adults. Setting Urban and suburban communities in a large metropolitan area. Participants Community-living participants (N=302) 70 years and older recruited from a previous population-based cohort. Interventions Not applicable. Main Outcome Measures Gait parameters including gait speed, stride length, double support and swing characteristics, and variability were assessed under single- and dual-task conditions involving cognitive challenges (eg, counting backward). A joint pain questionnaire assessed pain distribution in the back and major joints. We examined pain-gait relationships using multivariable linear regression and bootstrapping mediation procedures. Results Forty-three percent of participants had pain in 2 or more musculoskeletal sites. Pain distribution was related to slower gait speed and other gait characteristics for all gait conditions. Associations persisted after adjustment for age, sex, education, body mass index, medication, and vision. Decrements in gait measures related to pain were comparable with decrements in gait related to dual-task conditions. There were no differences in dual-task cost among the pain distribution groups. Adjusted for confounders, pain-gait relationships appear mediated by selective attention. Conclusions These findings suggest that chronic pain contributes to decrements in gait, including slower gait speed, and that it operates through a cognitively-mediated pathway. Further research is needed to understand the mechanisms via pain alters mobility and to develop interventions to improve mobility among older adults with chronic pain.

Background: Tripping over an obstacle is one of the most common causes of falls among older adults; however, the impact of obstacle parameters and subject characteristics are not well described. Objectives: To evaluate age-associated changes in the ability to negotiate obstacles and the role of obstacle parameters (e.g., anticipated vs. unanticipated, height, and available response time [ART]), and subject characteristics. Methods: Twenty healthy older adults (77.7 ± 3.4 years; 50% women) and 20 healthy young adults (29.3 ± 3.8 years; 50% women) underwent cognitive, gait, and balance testing before negotiating a computer-controlled obstacle course. The primary outcome measure was the ability to successfully negotiate the obstacles (without touching them). Results: The success rate for all subjects was higher when the obstacle was anticipated (99.0 ± 2.8%) than when unanticipated (66.0 ± 20.2%; p < 0.001). The obstacle height had a significant effect on the success rate (p = 0.022); the success rate was lower when the obstacle height was lower. No significant interaction between group and obstacle height was observed (p = 0.096). ART had no significant effect on the success rate (p = 0.294) in both of the groups (ART × group, p = 0.136). However, a significant interaction between group, obstacle height, and ART was found (p = 0.013), reflecting a lower success rate in the older adults when the obstacles were low and unanticipated. In general, older adults demonstrated a trend towards a lower success rate in all types of obstacles compared to the young adults (p = 0.057). Among the older adults, the success rate in the anticipated obstacle condition was correlated with stride length (ρ = 0.600, p = 0.005), step time coefficient of variation (ρ = –0.635, p = 0.003), and gait speed (rho = 0.530, p = 0.016). Montreal Cognitive Assessment scores tended to be related to the difference in the success rate between the anticipated and unanticipated conditions. Conclusions: These findings support the idea that motor and, to some degree, cognitive functions are needed to successfully negotiate obstacles, and provide new insights into the ability of older adults to successfully negotiate obstacles. Furthermore, the present results suggest that when it comes to the physical properties of obstacles, not all is as expected, and low obstacles may impose a greater danger to tripping than obstacles that have a higher height.

Background: Sleep interruptions and nocturnal hypokinesia are common in Parkinson's disease (PD). Pilot work using wearable technologies showed fewer nocturnal movements in patients with advanced PD compared to controls. However, the prevalence of these impairments in early stage of the disease and the influence of non-motor symptoms, and dopaminergic medication are unknown. Methods: This study evaluated wearable sensor data collected in 305 patients with PD at different Hohen and Yahr disease stages (HY HY H&Y3=77) and 205 healthy controls (HC). Subjects wore a tri-axial accelerometer continuously (24/7) on the lower back for at least 2 days. Percent upright-time and nighttime walking were defined based on the vertical axis of the acceleration signal and were classified as sleep interruptions. The number, velocity, time, side, and degree of rotations in bed during the night evaluated nocturnal movements. Findings: Nocturnal lying-time was similar between PD and controls (p=0.501), however, the number of turns and the turn velocity significantly decreased (p

Item does not contain fulltext 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.

Background: The traditional evaluation of gait in the laboratory during structured testing has provided important insights, but is limited by its "snapshot" character and observation in an unnatural environment. Wearables enable monitoring of gait in real-world environments over a week. Initial findings show that in-lab and real-world measures differ. As a step towards better understanding these gaps, we directly compared in-lab usual-walking (UW) and dual-task walking (DTW) to daily-living measures of gait.Methods: In-lab gait features (e.g., gait speed, step regularity, and stride regularity) derived from UW and DTW were compared to the same gait features during daily-living in 150 elderly fallers (age: 76.5 ± 6.3 years, 37.6% men). In both settings, features were extracted from a lower-back accelerometer. In the real-world setting, subjects were asked to wear the device for 1 week and pre-processing detected 30-s daily-living walking bouts. A histogram of all walking bouts was determined for each walking feature for each subject and then each subject's typical (percentile 50, median), worst (percentile 10) and the best (percentile 90) values over the week were determined for each feature. Statistics of reliability were assessed using Intra-Class correlations and Bland-Altman plots.Results: As expected, in-lab gait speed, step regularity, and stride regularity were worse during DTW, compared to UW. In-lab gait speed, step regularity, and stride regularity during UW were significantly higher (i.e., better) than the typical daily-living values (p p p = 0.205, p = 0.053, p = 0.013 respectively). ICC assessment and Bland-Altman plots indicated that in-lab values do not reliably reflect the daily-walking values.Conclusions: Gait values measured during relatively long (30-s) daily-living walking bouts are more similar to the corresponding values obtained in the lab during dual-task walking, as compared to usual walking. Still, gait performance during most daily-living walking bouts is worse than that measured during usual and dual-tasking in the lab. The values measured in the lab do not reliably reflect daily-living measures. That is, an older adult's typical daily-living gait cannot be estimated by simply measuring walking in a structured, laboratory setting.

Background Gait speed is a robust nonspecific predictor of health outcomes. We examined if combinations of gait speed and other mobility metrics are associated with specific health outcomes. Methods A sensor (triaxial accelerometer and gyroscope) placed on the lower back, measured mobility in the homes of 1,249 older adults (77% female; 80.0, SD = 7.72 years). Twelve gait scores were extracted from five performances, including (a) walking, (b) transition from sit to stand, (c) transition from stand to sit, (d) turning, and (e) standing posture. Using separate Cox proportional hazards models, we examined which metrics were associated with time to mortality, incident activities of daily living disability, mobility disability, mild cognitive impairment, and Alzheimer’s disease dementia. We used a single integrated analytic framework to determine which gait scores survived to predict each outcome. Results During 3.6 years of follow-up, 10 of the 12 gait scores predicted one or more of the five health outcomes. In further analyses, different combinations of 2–3 gait scores survived backward elimination and were associated with the five outcomes. Sway was one of the three scores that predicted activities of daily living disability but was not included in the final models for other outcomes. Gait speed was included along with other metrics in the final models predicting mortality and activities of daily living disability but not for other outcomes. Conclusions When analyzing multiple mobility metrics together, different combinations of mobility metrics are related to specific adverse health outcomes. Digital technology enhances our understanding of impaired mobility and may provide mobility biomarkers that predict distinct health outcomes.

Older adults with Parkinson’s disease (PD) rely on prefrontal activation to compensate for impaired motor function during the performance of complex mobility-related activities such as obstacle negotiation. However, the influence of the properties of the obstacles on prefrontal activation has not been systematically evaluated. Here, we examined the effects of obstacle height and anticipation time on prefrontal activation in patients with PD and older adults. 34 patients with PD (age: 67.4±5.7 years; 14 women) and 26 older adult controls (age: 71.3±8.9 years; 11 women) walked in an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 50 mm and 100 mm. Prefrontal activation was measured using functional Near-Infrared Spectroscopy (fNIRS); obstacle negotiation performance was measured using Kinect cameras. PD patients showed greater increases in prefrontal activation during and after obstacle crossing compared to the older adults (p

Recent work suggests that the prefrontal cortex is recruited during complex walking as a form of cognitive compensation to maintain performance in aging and neurodegenerative diseases. Evidence from fNIRS studies is accumulating on different patient groups demonstrating the utility of this method and its sensitivity to neural dysfunction. However a direct comparison that explores the specificity of prefrontal activation patterns has not been conducted. This process is essential towards implementing the use of fNIRS at the individual level. Data collected from four different cohorts; young adults, older adults, PD patients at different stages of the disease, and patients with Multiple-Sclerosis during challenging tasks will be presented. Overlap, commonality, disparity and variability between groups and conditions will be presented and modifiers and moderators that can affect individual performance will be discussed. Understanding individual differences in fNIRS response will enhance data interpretation and promote translation of this technology to clinical care applications.

Multidisciplinary interventions can improve gait and balance in patients with Parkinson’s disease (PD). However, it is not yet known if these interventions also positively impact the quality of daily-living walking. We, therefore, examined the effects of a multidisciplinary, intensive out-patient rehabilitation program (MIOR) as delivered by the rehabilitation center of EZRA–LEMARPE organization on gait and balance as measured in the clinic and on every-day walking, as measured during 1-week of continuous measurement. 46 PD patients (age: 70.05±7.71; gender: 31.3% women; disease duration: 8.85±6.27 yrs) were evaluated before and after participating in 8-weeks of physical, occupational, and hydro-therapy, boxing, and dance (3 days/week; 5 hrs/day). After the intervention, clinical measures of balance (MiniBest Test of Balance delta: 1.82±3.30 points, p=0.001), mobility (TUG delta: -1.78±6.15sec; p=0.001), and usual-walking speed (delta 19±16cm/s; p0.5). In exploratory analyses, subjects were categorized as responders (Rs) and non-responders (NRs) based on changes in their daily-living walking gait speed. Rs increased their daily-living gait speed (delta: 10±14cm/s; p

To determine whether older Mexican-Americans who cannot speak and/or understand spoken English have higher rates of mobility limitations or fear of falling than their English-speaking counterparts.We conducted a cross-sectional analysis of 1169 community-dwelling Mexican-Americans aged 72-96 years from the 2000-2001 wave of the Hispanic Established Population for the Epidemiological Study of the Elderly. Mobility limitations were defined as having a Short Physical Performance Battery score ≤9, and fear of falling by participant report of being somewhat, fairly, or very afraid of falling. We determined the rates and odds ratios, for having mobility limitations and fear of falling as a function of English ability in those who were 72-96,80, and ≥80 years of age.Among participants who were unable to speak and/or understand spoken English 85.7% had mobility limitations and 61.6% were afraid of falling, compared to 77.6% and 57.5%, respectively, of English speakers. Before adjusting for covariates, participants who did not speak and/or understand spoken English were more likely to have mobility limitations (odds ratio: 1.7; 95% CI: 1.3-2.4) but not fear of falling, compared to English speakers. Among those aged ≥80 years, but not those80 years, who did not speak or understand English were more likely to have mobility limitations (odds ratio: 4.8; 95% CI:2.0-11.5) and fear of falling (odds ratio: 2.0; 95% CI:1.3-3.1).Older Mexican-Americans who do not speak or understand spoken English have a higher rate of mobility limitations and fear of falling than their English-speaking counterparts.

Background Reduced arm swing is a well-known clinical feature of Parkinson's disease (PD), often observed early in the course of the disease. We hypothesized that subtle changes in arm swing and axial rotation may also be detectable in the prodromal phase. Objective The purpose of this study was to evaluate the relationship between the LRRK2-G2019S mutation, arm swing, and axial rotation in healthy nonmanifesting carriers and noncarriers of the G2019S mutation and in patients with PD. Methods A total of 380 participants (186 healthy nonmanifesting controls and 194 PD patients) from 6 clinical sites underwent gait analysis while wearing synchronized 3-axis body-fixed sensors on the lower back and bilateral wrists. Participants walked for 1 minute under the following 2 conditions: (1) usual walking and (2) dual-task walking. Arm swing amplitudes, asymmetry, variability, and smoothness were calculated for both arms along with measures of axial rotation. Results A total of 122 nonmanifesting participants and 67 PD patients were carriers of the G2019S mutation. Nonmanifesting mutation carriers walked with greater arm swing asymmetry and variability and lower axial rotation smoothness under the dual task condition when compared with noncarriers (P < .04). In the nonmanifesting mutation carriers, arm swing asymmetry was associated with gait variability under dual task (P = .003). PD carriers showed greater asymmetry and variability of movement than PD noncarriers, even after controlling for disease severity (P < .009). Conclusions The G2019S mutation is associated with increased asymmetry and variability among nonmanifesting participants and patients with PD. Prospective studies should determine if arm swing asymmetry and axial rotation smoothness may be used as motor markers of prodromal PD. © 2016 International Parkinson and Movement Disorder Society

Individuals with neurodegenerative disease (NDD) commonly have elevated cognitive-motor interference, change in either cognitive or motor performance (or both) when tasks are performed simultaneously, compared to healthy controls. Given that cognitive-motor interference is related to reduced community ambulation and elevated fall risk, it is a target of rehabilitation interventions. Areas covered: This review details the collective findings of previous dual task interventions in individuals with NDD. A total of 21 investigations focusing on 4 different neurodegenerative diseases and one NDD precursor (Parkinson's disease, multiple sclerosis, Alzheimer's disease (AD), dementia other than AD, and mild cognitive impairment) consisting of 721 participants were reviewed. Expert commentary: Preliminary evidence from interventions targeting cognitive-motor interference, both directly and indirectly, show promising results for improving CMI in individuals with neurodegenerative diseases. Methodological limitations, common to pilot investigations preclude firm conclusions. Well-designed randomized control trials targeting cognitive motor interference are warranted.

Contains fulltext : 167962.pdf (Publisher’s version ) (Closed access) BACKGROUND: Age-associated motor and cognitive deficits increase the risk of falls, a major cause of morbidity and mortality. Because of the significant ramifications of falls, many interventions have been proposed, but few have aimed to prevent falls via an integrated approach targeting both motor and cognitive function. We aimed to test the hypothesis that an intervention combining treadmill training with non-immersive virtual reality (VR) to target both cognitive aspects of safe ambulation and mobility would lead to fewer falls than would treadmill training alone. METHODS: We carried out this randomised controlled trial at five clinical centres across five countries (Belgium, Israel, Italy, the Netherlands, and the UK). Adults aged 60-90 years with a high risk of falls based on a history of two or more falls in the 6 months before the study and with varied motor and cognitive deficits were randomly assigned by use of computer-based allocation to receive 6 weeks of either treadmill training plus VR or treadmill training alone. Randomisation was stratified by subgroups of patients (those with a history of idiopathic falls, those with mild cognitive impairment, and those with Parkinson's disease) and sex, with stratification per clinical site. Group allocation was done by a third party not involved in onsite study procedures. Both groups aimed to train three times per week for 6 weeks, with each session lasting about 45 min and structured training progression individualised to the participant's level of performance. The VR system consisted of a motion-capture camera and a computer-generated simulation projected on to a large screen, which was specifically designed to reduce fall risk in older adults by including real-life challenges such as obstacles, multiple pathways, and distracters that required continual adjustment of steps. The primary outcome was the incident rate of falls during the 6 months after the end of training, which was assessed in a modified intention-to-treat population. Safety was assessed in all patients who were assigned a treatment. This study is registered with ClinicalTrials.gov, NCT01732653. FINDINGS: Between Jan 6, 2013, and April 3, 2015, 302 adults were randomly assigned to either the treadmill training plus VR group (n=154) or treadmill training alone group (n=148). Data from 282 (93%) participants were included in the prespecified, modified intention-to-treat analysis. Before training, the incident rate of falls was similar in both groups (10.7 [SD 35.6] falls per 6 months for treadmill training alone vs 11.9 [39.5] falls per 6 months for treadmill training plus VR). In the 6 months after training, the incident rate was significantly lower in the treadmill training plus VR group than it had been before training (6.00 [95% CI 4.36-8.25] falls per 6 months; p

Complexity of human physiology and physical behavior has been suggested to decrease with aging and disease and make older adults more susceptible to falls. The present study investigates complexity in daily life walking in community-dwelling older adult fallers and non-fallers measured by a 3D inertial accelerometer sensor fixed to the lower back. Complexity was expressed using new metrics of entropy: refined composite multiscale entropy (RCME) and refined multiscale permutation entropy (RMPE). The study re-analyses data of 3 days daily-life activity originally described by Weiss et al. (2013) . The data set contains inertial sensor data from 39 older persons reporting less than 2 falls and 32 older persons reporting two or more falls during the previous year. The RCME and the RMPE were derived for trunk acceleration and velocity signals from walking epochs of 50 s using mean and variance coarse graining of the signals. Discriminant abilities of the entropy metrics were assessed using a partial least square discriminant analysis. Both RCME and RMPE successfully distinguished between the daily-life walking of the fallers and non-fallers (AUC>0.8) and performed better than the 35 conventional gait features investigated by Weiss et al. (2013) . Higher complexity was found in the vertical and mediolateral directions in the non-fallers for both entropy metrics. These findings suggest that RCME and RMPE can be used to improve the assessment of fall risk in older people.

Body-fixed sensors (BFS), e.g., accelerometers worn for several days, can be used to augment the traditional clinical assessment. Long-term recordings obtained with BFS have been applied to study tremor, postural control, freezing of gait, turning abilities, motor response fluctuations and fall risk among older adults and patients with Parkinson's disease (PD). We aimed to test whether BFS-derived measures of transitions differ between patients with PD and healthy controls, and to evaluate whether there are differences among patients with mild PD, compared to more severe patients, and to controls. We also explored the added value of the metrics extracted from the sensor as compared to traditional testing in the lab. Ninety-nine patients with PD and 38 healthy older adults (HOA) participated in this study and wore a body-fixed sensor for 3 days. Walk-to-sit (n = 3286) and Sit-to-walk (n = 2858) transitions were analyzed and a machine learning algorithm was applied to distinguish between the groups. Significant differences in transitions were observed between PD patients and HOA, between mild and severe PD, and between mild PD and HOA, both in temporal and distribution features. The machine learning algorithm discriminated patients from HOA (accuracy = 92.3 %), mild from severe patients (accuracy = 89.8 %), and mild patients from HOA (accuracy = 85.9 %). These initial results suggest that body-fixed sensor-derived metrics of everyday transitions can characterize disease severity and differentiate mild PD patients from healthy older adults. Perhaps this approach can help with the integration of BFS into clinical care and the tracking of disease progression and the response to therapy.

Independent control of the right and left ankles (differentiation) may be a motor control mechanism linking impaired coordination and mobility limitations. We tested the hypotheses that motor control differentiation of the ankles, as measured using Cross-Sample Entropy, during antiphase coordination at two movement frequencies, is associated with impaired coordination (high ankle coordination variability) and mobility limitations (Short Physical Performance Battery score ≤9). We conducted a cross-sectional study of community-dwelling older adults (N = 133) aged 80.04 (±4.67) years. In linear regression modeling, low ankle Cross-Sample Entropy (low motor control differentiation) was associated with poor (i.e., high) coordination variability at the slower (P = 0.026), but not the faster (P = 0.447), ankle movement frequency. In logistic regression modeling, low Cross-Sample Entropy at the slower (OR = 1.67; 95 % CI: 1.07–2.59) and faster (OR = 2.38; 95 % CI: 1.43–3.94) ankle movement frequencies were associated with increased odds for mobility limitations. Our findings support the hypothesis that ankle differentiation may be a motor control mechanism that links impaired coordination with mobility limitations.

Accumulating evidence has shown that mobility is a multi-dimensional construct. In this prospective study, we examined if previously validated body-fixed sensor derived mobility metrics extracted from an inertial measurement unit worn on the lower back (e.g., gait speed, angular velocity during turning, stride regularity, sway amplitude during standing) are associated with diverse health outcomes among older adults in the Rush Memory and Aging Project. Then we examined if different combinations of these metrics predict distinct outcomes. Mobility metrics were extracted from 1,249 community-dwelling older adults (mean age 81.2 years, 78% female) who were followed on average for 3.6 years. Cox proportional hazards models controlling for age, sex, education and race with backward elimination determined the final combination of the specific metrics that best predicted six outcomes: mortality, disability in activities of daily living (ADL), mobility disability, multiple falls, mild cognitive impairment (MCI), and Alzheimer’s dementia (AD). Different combinations of mobility metrics independently predicted these six outcomes. For example, sway was one of the independent predictors of ADL disability, but was not included in the final models of other outcomes. Stride regularity independently predicted mortality, MCI and AD, but not ADL or mobility disability. Interestingly, gait speed was included as an independent predictor of mortality and ADL disability, but not of falls, mobility disability, MCI or AD. Mobility metrics extracted from a wearable sensor complement gait speed metrics. Quantifying multiple facets of mobility facilitates the identification of mobility signatures that enhance risk stratification for distinct adverse health outcomes among older adults.

Accumulating evidence points to an increased fall risk among older adults who have persistent multisite pain. A better understanding of this pain hazard could lead to new interventions to reduce fall risk in older adults. The MOBILIZE Boston Study II included a battery of tests to assess the attentional domain, as well as the problem of persistent multisite pain. The 354 participants completed monthly fall calendars during the subsequent 2 years. Incidence rate ratios for falls were derived from multivariable negative binomial models, adjusted for fall risk factors. We found that elders who had multisite pain had a 51% increase in fall risk (adj. IRR=1.51, 95% CI: 1.51–2.10). Several measures of attention mediated the pain-falls relationship including measures of selective attention, visual attention and attentional switching. Studies are needed to determine whether interventions that incorporate attentional challenges could reduce fall risk in older adults who have multisite pain.

Gait initiation, a task that demands the orchestration of cognitive and motor processes in order to transition from a standing posture to the onset of walking, can be partitioned into three phases: 1) The duration of motor planning extends from the signal to move until the onset of anticipatory postural adjustments (APA), time to APA. 2) The APA ends when the center-of-pressure returns to baseline; 3) Step duration, the “motor” implementation time, extends from the end of APA to heel-strike. To measure gait initiation metrics in large-scale studies, we developed an automated approach based on changes in the waveforms obtained from 3D accelerometer recordings from the lower back. To validate these metrics, we compared them with metrics extracted from concurrent instrumented gait-mat recordings in 41 healthy young adults (31.2 ± 5.0 yrs; %51 women) and 14 older adult women (mean age: 76.1 ± 6.3 yrs). Time to APA, APA duration, and step duration estimates derived from the wearable sensor and gait-mat were highly correlated (p

BACKGROUND Falls are frequent in Parkinson's disease and aging. Impairments in the cholinergic-mediated attentional supervision of gait may contribute to increased fall risk, especially when obstacles challenge gait. Interventions combining motor-cognitive approaches have been shown to improve motor performance, cognitive skills, and falls number. Here, we hypothesized that an intervention simulating an attention-demanding walking condition could affect not only complex gait performance and fall risk but also short-latency afferent inhibition (SAI), as a marker of cholinergic activity. METHODS Thirty-nine participants at falls risk (24 Parkinson's disease participants and 15 older adults) were recruited in a randomized controlled trial. Participants were assigned to treadmill training or treadmill training with non-immersive virtual reality intervention and trained three times a week for 6 weeks. SAI, a transcranial magnetic stimulation paradigm, was used to assess cholinergic activity. Gait kinematics was measured during usual walking and while negotiating physical obstacles. Transcranial magnetic stimulation and gait assessments were performed pre, post, and 6 months post-intervention. RESULTS Treadmill training combined with non-immersive virtual reality induced an increase in inhibition of the SAI protocol on cortical excitability, improved obstacle negotiation performance, and induced a reduction of the number of falls compared with treadmill training. Furthermore, the more SAI increased after training, the more the obstacle negotiation performance improved and fall rate decreased. CONCLUSIONS We provide evidence that an innovative rehabilitation approach targeting cognitive components of complex motor actions can induce changes in cortical cholinergic activity, as indexed by SAI, thereby enabling functional gait improvements.

Objective To investigate EEG changes during an auditory odd-ball task while walking (dual-task) in young adults, older adults, and patients with Parkinson's disease. Methods 11 young adults, 10 older adults, and 10 patients with Parkinson’s disease (PD) performed an auditory oddball task during standing and walking on a treadmill, while wearing a wireless EEG cap. The amplitude and latency of P300 were compared between groups and within conditions using linear mix model analysis. Gait was evaluated using wearable sensors and cognition was assessed using the Color Trail Test. Results P300 latency became longer during walking in all groups (p = 0.005). During walking, older adults (p = 0.005) and patients with PD (p = 0.001) showed prolonged P300 latency compared to young adults. Significant task by group interaction was found in P300 amplitude (p = 0.008). Patients with PD demonstrated reduced P300 amplitude during walking compared to standing (p = 0.023). Among all subjects, better motor and cognitive performance correlated with shorter P300 latency (r = 0.457, p = 0.014 and r = 0.431, p = 0.040, respectively). Conclusions These findings provide direct evidence of the physiological recruitment of attentional networks during walking and their impact by ageing and disease. Significance This study is the first to report on changes in P300 latency and amplitude during dual-task oddball walking in older adults and patients with PD.

Background Impairments in biomechanics and neural control can disrupt the timing and muscle pattern activation necessary for smooth gait. Gait is one of the most affected motor characteristics in Parkinson’s disease (PD), but its smoothness has not been well-studied. This work applies the recently proposed spectral arc length measure (SPARC) to study, for the first time, gait in patients with PD. We hypothesized that the gait of patients with PD would be less smooth than that of healthy controls, as reflected in the SPARC measures. Methods The gait of 101 PD patients and 39 healthy controls was assessed using an inertial sensor. Smoothness of gait was estimated with SPARC (respectively from acceleration and angular velocity signals, SPARC-Acc and SPARC-Gyro) and harmonic ratios. Correlations between SPARC, traditional gait measures and the motor part of the Unified Parkinson’s Disease Rating Scale (UPDRS) were evaluated. Measurements and analysis were conducted with and without anti-PD medication. Results SPARC measures were lower (less smooth) in PD than in controls (SPARC-Acc: PD: − 6.11 ± 0.74; CO: -5.17 ± 0.79; p 1). SPARC measures were correlated with UPDRS motor score (r = − 0.65), while they were independent of other measures of gait smoothness. PD gait in the on state was smoother than in the off state (p

Background When older adults turn to sit, about 80% of the subjects complete the turn before starting to sit i.e., a distinct-strategy, while in about 20%, part of the turning and sitting take place concurrently, i.e., an overlapping-strategy. A prolonged duration of the separation between tasks in the distinct-strategy (D-interval) and a prolonged duration of the overlap interval in overlapping-strategy (O-interval) are related to worse motor symptoms and poorer cognition. In the present study, we evaluated what strategy is employed by patients with Parkinson’s disease (PD) when they transition from turning to sitting. Methods 96 participants with PD performed turn to sit as part of the Timed Up and Go test, both with and without medications, while wearing a body-fixed sensor. We quantified the turn-to-sit transition and determined which strategy (distinct or overlapping) was employed. We then stratified the cases and used regression models adjusted for age, gender, height, and weight to examine the associations of the D-interval or O-interval with parkinsonian features and cognition. Results Most patients (66%) employed the overlapping-strategy, both off and on anti-parkinsonian medications. Longer O-intervals were associated with longer duration of PD, more severe PD motor symptoms, a higher postural-instability-gait-disturbance (PIGD) score, and worse freezing of gait. Longer D-intervals were not associated with disease duration or PD motor symptoms. Neither the D- nor O-intervals were related to cognitive function. Individuals who employed the overlapping-strategy had more severe postural instability (i.e., higher PIGD scores), as compared to those who used the distinct-strategy. Significance In contrast to older adults without PD, most patients with PD utilize the overlapping strategy. Poorer postural and gait control are associated with the strategy choice and with the duration of concurrent performance of turning and sitting. Additional work is needed to further explicate the mechanisms underlying these strategies and their clinical implications.

Purpose: To examine the feasibility and efficacy of a combined motor-cognitive training using virtual reality to enhance behavior, cognitive function and dual-tasking in children with Atten...

Background: The use of miniaturized magneto-inertial measurement units (MIMUs) allows for an objective evaluation of gait and a quantitative assessment of clinical outcomes. Spatial and temporal parameters are generally recognized as key metrics for characterizing gait. Although several methods for their estimate have been proposed, a thorough error analysis across different pathologies, multiple clinical centers and on large sample size is still missing. The aim of this study was to apply a previously presented method for the estimate of spatio-temporal parameters, named Trusted Events and Acceleration Direct and Reverse Integration along the direction of Progression (TEADRIP), on a large cohort (236 patients) including Parkinson, mildly cognitively impaired and healthy older adults collected in four clinical centers. Data were collected during straight-line gait, at normal and fast walking speed, by attaching two MIMUs just above the ankles. The parameters stride, step, stance and swing durations, as well as stride length and gait velocity, were estimated for each gait cycle. The TEADRIP performance was validated against data from an instrumented mat.Results: Limits of agreements computed between the TEADRIP estimates and the reference values from the instrumented mat were − 27 to 27 ms for Stride Time, − 68 to 44 ms for Stance Time, − 31 to 31 ms for Step Time and − 67 to 52 mm for Stride Length. For each clinical center, the mean absolute errors averaged across subjects for the estimation of temporal parameters ranged between 1 and 4%, being on average less than 3% (Conclusions: The TEADRIP method was effectively validated on a large number of healthy and pathological subjects recorded in four different clinical centers. Results showed that the spatio-temporal parameters estimation errors were consistent with those previously found on smaller population samples in a single center. The combination of robustness and range of applicability suggests the use of the TEADRIP as a suitable MIMU-based method for gait spatio-temporal parameter estimate in the routine clinical use. The present paper was awarded the "SIAMOC Best Methodological Paper 2017".

Objectives To assess the feasibility and inform design features of a fully powered randomized controlled trial (RCT) evaluating the effects of Tai Chi (TC) in Parkinson’s disease (PD) and to select outcomes most responsive to TC assessed during off-medication states. Design Two-arm, wait-list controlled RCT. Settings Tertiary care hospital. Subjects Thirty-two subjects aged 40–75 diagnosed with idiopathic PD within 10 years. Interventions Six-month TC intervention added to usual care (UC) versus UC alone. Outcome Measures Primary outcomes were feasibility-related (recruitment rate, adherence, and compliance). Change in dual-task (DT) gait stride-time variability (STV) from baseline to 6 months was defined, a priori, as the clinical outcome measure of primary interest. Other outcomes included: PD motor symptom progression (Unified Parkinson’s Disease Rating Scale [UPDRS]), PD-related quality of life (PDQ-39), executive function (Trail Making Test), balance confidence (Activity-Specific Balance Confidence Scale, ABC), and Timed Up and Go test (TUG). All clinical assessments were made in the off-state for PD medications. Results Thirty-two subjects were enrolled into 3 sequential cohorts over 417 days at an average rate of 0.08 subjects per day. Seventy-five percent (12/16) in the TC group vs 94% (15/16) in the UC group completed the primary 6-month follow-up assessment. Mean TC exposure hours overall: 52. No AEs occurred during or as a direct result of TC exercise. Statistically nonsignificant improvements were observed in the TC group at 6 months in DT gait STV (TC [20.1%] vs UC [−0.1%] group [effect size 0.49; P = .47]), ABC, TUG, and PDQ-39. UPDRS progression was modest and very similar in TC and UC groups. Conclusions Conducting an RCT of TC for PD is feasible, though measures to improve recruitment and adherence rates are needed. DT gait STV is a sensitive and logical outcome for evaluating the combined cognitive-motor effects of TC in PD.

BACKGROUND: It is well established that facing a cognitive challenge while carrying out a motor task interferes with the motor task performance, and in general the ability of handling a dual-task declines progressively with aging. However, the reasons for this decline have not been fully elucidated. Understanding the association between usual-walking gait patterns and dual-task walking performance may provide new insights into the mechanisms that lead to gait deterioration in normal aging and its link to motor and cognitive function. RESEARCH QUESTION: Our aim was to assess usual gait parameters in kinematics and kinetics to understand how these parameters are related with a specific task in dual-task walking. METHODS: We hypothesized that difficulty in dual-task walking would be associated with gait deteriorations as reflected in range of motion and mechanical work expenditure. We tested this hypothesis by quantifying the gait of 383 participants in the Baltimore Longitudinal Study of Aging (68% of whom successfully completed the dual-task walk, 21% failed the motor task, and 11% failed the cognitive task). RESULTS: Compared to successful performers, participants who failed the single motor task had slower gait speed, shorter stride length, higher cadence, and lower range of motion in the knee and ankle joints (p < 0.05, for all), while the participants who failed the cognitive task while walking had longer double support time (p = 0.003), and greater knee absorptive mechanical work (p = 0. 001) and lower ankle generative mechanical work (p < 0.001). SIGNIFICANCE: These results suggest that dual-task walking may be useful for monitoring subtle and diverse gait deteriorations in aging and possibly for designing interventions for maintaining and regaining proper gait patterns in older adults.

Recent findings suggest that transcranial direct current stimulation of the primary motor cortex may ameliorate freezing of gait. However, the effects of multitarget simultaneous stimulation of motor and cognitive networks are mostly unknown. The objective of this study was to evaluate the effects of multitarget transcranial direct current stimulation of the primary motor cortex and left dorsolateral prefrontal cortex on freezing of gait and related outcomes.Twenty patients with Parkinson's disease and freezing of gait received 20 minutes of transcranial direct current stimulation on 3 separate visits. Transcranial direct current stimulation targeted the primary motor cortex and left dorsolateral prefrontal cortex simultaneously, primary motor cortex only, or sham stimulation (order randomized and double-blinded assessments). Participants completed a freezing of gait-provoking test, the Timed Up and Go, and the Stroop test before and after each transcranial direct current stimulation session.Performance on the freezing of gait-provoking test (P = 0.010), Timed Up and Go (P = 0.006), and the Stroop test (P = 0.016) improved after simultaneous stimulation of the primary motor cortex and left dorsolateral prefrontal cortex, but not after primary motor cortex only or sham stimulation.Transcranial direct current stimulation designed to simultaneously target motor and cognitive regions apparently induces immediate aftereffects in the brain that translate into reduced freezing of gait and improvements in executive function and mobility. © 2018 International Parkinson and Movement Disorder Society.

Cerebral atrophy has been detected in patients with Parkinson’s disease (PD) both with and without dementia, however differentiation based on genetic status has thus far not yielded robust findings. We assessed cortical thickness and subcortical volumes in a cohort of PD patients and healthy controls carriers of the G2019S mutation in the LRRK2 gene and the common GBA mutations, in an attempt to determine whether genetic status influences structural indexes. Cortical thickness and subcortical volumes were computed and compared between six groups of participants; idiopathic PD, GBA-PD, LRRK2-PD, non-manifesting non-carriers (NMNC), GBA-non-manifesting carriers (NMC) and LRRK2-NMC utilizing the FreeSurfer software program. All participants were cognitively intact based on a computerized cognitive assessment battery. Fifty-seven idiopathic PD patients, 9 LRRK2-PD, 12 GBA-PD, 49 NMNC, 41 LRRK2-NMC and 14 GBA-NMC participated in this study. Lower volumes among patients with PD compared to unaffected participants were detected in bilateral hippocampus, nucleus accumbens, caudate, thalamus, putamen and amygdala and the right pallidum (p = 0.016). PD patients demonstrated lower cortical thickness indexes in a majority of regions assessed compared with non-manifesting participants. No differences in cortical thickness and subcortical volumes were detected within each of the groups of participants based on genetic status. Mutations in the GBA and LRRK2 genes are not important determinants of cortical thickness and subcortical volumes in both patients with PD and non-manifesting participants. PD is associated with a general reduction in cortical thickness and sub-cortical atrophy even in cognitively intact patients.

Difficulty in turning while walking is common among patients with Parkinson’s disease (PD). This difficulty often leads to significant disability, falls, and loss of function; moreover, turning is a common trigger for freezing of gait (FoG). We hypothesized that the quantity and quality of turning mobility while walking during daily life would be different among subjects with PD with and without FoG. Here, we investigated, for the first time, the turning quality during daily life as it relates to FoG in people with PD using a single inertial sensor. Ninety-four subjects with PD (among whom 25 had FoG) wore an inertial sensor attached by a belt on the lower back during normal daily activity consecutively for 3 days. An algorithm identified periods of walking and calculated the number and quality metrics of turning. Quality, but not the quantity, of turning at home was different in freezers compared to the non-freezers. The number of turns (19.3 ± 9.2/30 min in freezers, 22.4 ± 12.9/30 min non-freezers; p = 0.194) was similar in the two groups. Some aspects of quality of turns, specifically mean jerkiness, mean and variability of medio-lateral jerkiness were significantly higher (p

Background: Recent work demonstrated that the gait of people with mild cognitive impairment (MCI) differs from that of age-matched controls and, in general, that walking ability, as measured in the clinic, does not necessarily reflect actual, daily performance. We evaluated if the quantity and quality of everyday walking (ie, community ambulation) differs in older adults with MCI, compared to age-matched controls. Methods: Inclusion criteria included: age 65–90 years, able to walk at least 5 minutes unassisted, and ≥2 falls in the past 6 months. Subjects with MCI were included if they scored 0.5 on the Clinical Dementia Rating Scale. To assess stepping quantity and quality, subjects wore a triaxial accelerometer on the lower-back for 7 days. Results: Age and gender were similar (p > .10) in MCI (n = 36, 77.8 ± 6.4 years; 27.8% men) and controls (n = 100, 76.0 ± 6.2 years; 22.0% men). As expected, Montreal Cognitive Assessment scores were lower (p < .001) in MCI (21.31 ± 4.05), compared to controls (25.81 ± 2.64). Walking time was lower (p = .016) in MCI (0.74 ± 0.48 hours/d), compared to controls (1.05 ± 0.66 hours/d). Within-bout walking (eg, stride regularity) was less consistent (p = .024) in MCI (0.51 ± 0.14), compared to controls (0.58 ± 0.14). Changes in stride regularity across bouts were lower (p < .001) in MCI (0.13 ± 0.04), compared to controls (0.17 ± 0.01). Conclusions: Older adults with MCI walk less and with a more variable within-bout and less variable across-bout walking pattern, as compared to cognitively-intact subjects matched with respect to age and gender. These findings extend previous clinical work and suggest that MCI affects both the quantity and quality of community ambulation. ispartof: Journals of Gerontology A, Biological Sciences and Medical Sciences vol:73 issue:8 pages:1078-1082 ispartof: location:United States status: published

Background. In a randomized control trial conducted in patients with Parkinson’s disease, a treadmill training program combined with virtual reality that targeted motor and cognitive aspects of safe ambulation led to fewer falls, compared with treadmill training alone. Objective. To investigate if the 2 types of training differentially affected prefrontal activation and if this might explain differences in fall rates after the intervention. Methods. Sixty-four patients with Parkinson’s disease were randomized into the treadmill training arm (n = 34, mean age 73.1 ± 1.1 years, 64% men, disease duration 9.7 ± 1.0 years) or treadmill training with virtual reality arm (n = 30, mean age 70.1 ± 1.3 years, 71% men, disease duration 8.9 ± 1.1 years). Prefrontal activation during usual, dual-task, and obstacle negotiation walking was assessed before and after 6 weeks of training, using a functional near-infrared spectroscopy system. Results. Treadmill training with and without virtual reality reduced prefrontal activation during walking ( P < .001), with specific interactions related to training arm ( P = .01), lateralization ( P = .05), and walking condition ( P = .001). For example, among the subjects who trained with treadmill training alone, prefrontal activation during dual-task walking and obstacle negotiation increased after training, while in the combined training arm, activation decreased. Conclusions. Prefrontal activation during usual and during more challenging walking conditions can be altered in response to 2 different types of training. The addition of a cognitive training component to a treadmill exercise program apparently modifies the effects of the training on the magnitude and lateralization of prefrontal activation and on falls, extending the understanding of the plasticity of the brain in PD.

Freezing of gait (FoG) is a common gait impairment among patients with advanced Parkinson's disease. FoG is associated with falls and negatively impacts the patient's quality of life. Wearable systems that detect FoG in real time have been developed to help patients resume walking by means of rhythmic cueing. Current methods focus on detection, which require FoG events to happen first, while their prediction opens the road to preemptive cueing, which might help subjects to avoid freeze altogether. We analyzed electrocardiography (ECG) and skin-conductance (SC) data from 11 subjects who experience FoG in daily life, and found statistically significant changes in ECG and SC data just before the FoG episodes, compared to normal walking. Based on these findings, we developed an anomaly-based algorithm for predicting gait freeze from relevant SC features. We were able to predict 71.3% from 184 FoG with an average of 4.2 s before a freeze episode happened. Our findings enable the possibility of wearable systems, which predict with few seconds before an upcoming FoG from SC, and start external cues to help the user avoid the gait freeze.

Background Pain related to many age-related chronic conditions is a burdensome problem in elderly adults and may also interfere with cognitive functioning. The purpose of this study was to examine the cross-sectional relationship between measures of pain severity and pain interference and cognitive performance in community-living older adults. Methods We studied 765 participants in the Maintenance of Balance Independent Living Intellect and Zest (MOBILIZE) Boston Study, a population-based study of persons aged 70 and older. Global pain severity and interference were measured using the Brief Pain Inventory subscales. The neuropsychological battery included measures of attentional capacity (Trail Making Test A, WORLD Test), executive function (Trail Making Test B and Delta, Clock-in-a-Box, Letter Fluency), memory (Hopkins Verbal Learning Test), and a global composite measure of cognitive function. Multivariable linear regression models were used to analyze the relationship between pain and cognitive functioning. Results Elderly adults with more severe pain or more pain interference had poorer performance on memory tests and executive functioning compared to elders with none or less pain. Pain interference was also associated with impaired attentional capacity. Additional adjustment for chronic conditions, behaviors, and psychiatric medication resulted in attenuation of many of the observed associations. However, the association between pain interference and general cognitive function persisted. Conclusions Our findings point to the need for further research to understand how chronic pain may contribute to decline in cognitive function and to determine strategies that may help in preventing or managing these potential consequences of pain on cognitive function in older adults.

Cognitive decline amongst older adults is a significant public health concern. There is growing interest in behavioral interventions, including exercise, for improving cognition. Studies to date suggest tai chi (TC) may be a safe and potentially effective exercise for preserving cognitive function with aging; however, its short-term and potential long-term impact on physically active, healthy adults is unclear.To compare differences in cognitive function among long-term TC expert practitioners and age-matched and gender-matched TC-naïve adults and to determine the effects of short-term TC training on measures of cognitive function in healthy, nonsedentary adults.A hybrid design including an observational comparison and a 2-arm randomized clinical trial (RCT).Healthy, nonsedentary, TC-naive adults (50 y-79 y) and age-matched and gender-matched long-term TC experts.A cross-sectional comparison of cognitive function in healthy TC-naïve (n=60) and TC expert (24.5 y ÷ 12 y experience; n=27) adults: TC-naïve adults then completed a 6-month, 2-arm, wait-list randomized clinical trial of TC training. Six measures of cognitive function were assessed for both cross-sectional and longitudinal comparisons.TC experts exhibited trends towards better scores on all cognitive measures, significantly so for category fluency (P=.01), as well as a composite z score summarizing all 6 cognitive assessments (P=.03). In contrast, random assignment to 6 months of TC training in TC-naïve adults did not significantly improve any measures of cognitive function.In healthy nonsedentary adults, long-term TC training may help preserve cognitive function; however, the effect of short-term TC training in healthy adults remains unclear.ClinicalTrials.gov NCT01340365.背景：老年人认知功能衰退是一个 重要的公共健康问题。通过行为干 预（包括锻炼）来改善认知功能日 益受到关注。现有研究表明，太极 拳可能是防止认知功能随年龄衰退 的安全有效锻炼方式，但它对经常 运动的健康成人的短期和长期作用 尚不明确。目的：比较长期打太极拳的高手与 未打过太极拳的同等年龄和性别的 成人在认知功能方面的差异，并确 定短期太极拳运动对健康非久坐成 人的认知功能的影响。设计：采用混合设计，既包括观察 性比较，也包括一项两分组随机临 床试验 (RCT)参与者：未打过太极拳的健康非久 坐成人（50-79 岁）与年龄及性别 相仿的长期打太极拳高手方法：对未打过太极拳的健康成人 (n=60) 和太极拳高手（拥有 24.5 ± 12 年的经验；n=27）的认知功能进行比较：未打过太极拳的成人 随后按侯选表，完成了一项为期 6 个月、两分组太极训练随机临床试 验。不管是剖面代表性比较，还是 纵向比较，均评估了 6 项认知功 能指标。结果：太极拳高手在所有认知功能 指标上均表现出更高得分倾向，在 流利度项目上尤其显著 (P=0.01) ，在 6 个指标的综合评分 z 值上 亦如此 (P=0.03)。相对之下，未 打过太极拳的成人经随机分配接受 6 个月的太极拳训练后，其认知功 能指标未出现显著改善。结论：健康非久坐成人接受长期太 极拳训练可能有助于保存认知功 能，但短期太极拳训练对健康成人 的效果仍不明确。试验注册编号：ClinicalTrials.gov NCT01340365.El deterioro cognitivo entre los adultos más mayores es un importante problema de salud pública. Existe un creciente interés en las intervenciones conductuales, incluido el ejercicio, para mejorar la cognición. Los estudios realizados hasta la fecha sugieren que el taichí (TC) podría ser un ejercicio seguro y posiblemente eficaz para preservar la función cognitiva con el envejecimiento; sin embargo, su impacto a corto plazo y su posible impacto a largo plazo en adultos sanos y físicamente activos no está claro.Comparar las diferencias en la función cognitiva entre las personas expertas que practican TC a largo plazo y adultos que no habían practicado TC anteriormente de la misma edad y sexo y determinar los efectos del entrenamiento con TC a corto plazo en las medidas de la función cognitiva en adultos no sedentarios sanos.Diseño híbrido que incluía una comparación observacional y un ensayo clínico aleatorizado (ECA) de 2 grupos.Adultos no sedentarios sanos que no habían practicado TC anteriormente (50 años y 79 años) y expertos en TC a largo plazo de la misma edad y sexo.Comparación transversal de la función cognitiva en adultos santos que no habían practicado TC anteriormente (n = 60) y expertos en TC (24,5 ± 12 años de experiencia; n = 27) adultos: adultos santos que no habían practicado TC anteriormente completaron un ensayo clínico aleatorizado de lista de espera de entrenamiento con TC de 2 grupos y 6 meses de duración. Se evaluaron seis medidas de la función cognitiva para realizar comparaciones tanto transversales como longitudinales.Los expertos en TC mostraron tendencias hacia mejores puntuaciones en todas las medidas cognitivas, que fueron significativas en la categoría de fluidez (P = 0,01), así como en la puntuación z compuesta que resumía las 6 evaluaciones cognitivas (P = 0,03). Por el contrario, la asignación aleatoria a los 6 meses de entrenamiento con TC en adultos que no habían practicado TC anteriormente no mejoró significativamente ninguna de las medidas de la función cognitiva.En los adultos sanos no sedentarios, el entrenamiento con TC a largo plazo podría ayudar a preservar la función cognitiva; sin embargo, el efecto del entrenamiento con TC a corto plazo en adultos sanos sigue sin estar claro. Registro del ensayo: ClinicalTrials.gov NCT01340365.

Functional performance-based tests like the Timed Up and Go test (TUG) and its subtasks have been associated with fall risk, future disability, nursing home admission, and other poor outcomes in older adults. However, a single measurement in the laboratory may not fully reflect the subject's condition and everyday performance. To begin to validate an approach based on long-term, continuous monitoring, we investigated the sit-to-walk and walk-to-sit transitions performed spontaneously and naturally during daily living.Thirty young adults, 38 older adults, and 33 elderly (idiopathic) fallers were studied. After evaluating mobility and functional performance in the laboratory, participants wore an accelerometer on their lower back for 3 days. We analyzed the sit-to-walk and walk-to-sit transitions using temporal and distribution-related features. Machine learning algorithms assessed the feature set's ability to discriminate between the different cohorts.5,027 transitions were analyzed. Significant differences were observed between the young and older adults (p.044) and between the fallers and older adults (p.032). Machine learning algorithms classified the young and older adult with an accuracy of about 98% and the fallers and the older adults at 88%, which was better than the results achieved using traditional laboratory assessments (~72%).Features extracted from the multiple transitions recorded during daily living apparently reflect changes associated with aging and fall risk. Long-term monitoring of temporal features and their distribution may be helpful to provide a more complete and accurate assessment of the effects of aging and fall risk on daily function and mobility.

Background and Purpose— Patients with stroke are at risk for developing cognitive impairment. We tested whether the assessment of balance and gait can enhance the prediction of long-term cognitive outcome in stroke survivors. Methods— Participants were patients with first-ever, mild-moderate ischemic stroke or transient ischemic attack from the Tel Aviv Brain Acute Stroke Cohort (TABASCO) study, a large prospective cohort study, who underwent 3-T MRI and were followed for ≥2 years using neurological, neuropsychological, and mobility examinations 6, 12, and 24 months after the index event. Results— Data were available for 298 patients (age: 66.7±9.6 years). Forty-six participants (15.4%) developed cognitive decline (CD) over the 2 years of follow-up. The CD group and cognitively intact group did not differ in their neurological deficits or in their infarct volume or location. Nonetheless, 6 months after stroke, the Timed Up and Go test took longer in those who later developed CD ( P P P P =0.006). Separate analyses of the patients with transient ischemic attack revealed similar results. Multivariate regression analysis showed that Timed Up and Go times >12 s at 6 months after stroke/transient ischemic attack was a significant independent risk marker of CD 24 months after stroke (odds ratio=6.07, 95% confidence interval: 1.36–27.15). Conclusions— These results suggest that measures of balance and gait are significant risk markers of cognitive status 2 years after stroke. Relatively simple, performance-based tests of mobility may enhance the identification of stroke/transient ischemic attack survivors who have an increased risk of developing CD. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01926691.

People with Parkinson’s disease (PD) suffer from declining mobility capabilities, which cause a prevalent risk of falling. Commonly, short periods of motor blocks occur during walking, known as freezing of gait (FoG). To slow the progressive decline of motor abilities, people with PD usually undertake stationary motor-training exercises in the clinics or supervised by physiotherapists. We present a wearable system for the support of people with PD and FoG. The system is designed for independent use. It enables motor training and gait assistance at home and other unsupervised environments. The system consists of three components. First, FoG episodes are detected in real time using wearable inertial sensors and a smartphone as the processing unit. Second, a feedback mechanism triggers a rhythmic auditory signal to the user to alleviate freeze episodes in an assistive mode. Third, the smartphone-based application features support for training exercises. Moreover, the system allows unobtrusive and long-term monitoring of the user’s clinical condition by transmitting sensing data and statistics to a telemedicine service. We investigate the at-home acceptance of the wearable system in a study with nine PD subjects. Participants deployed and used the system on their own, without any clinical support, at their homes during three protocol sessions in 1 week. Users’ feedback suggests an overall positive attitude toward adopting and using the system in their daily life, indicating that the system supports them in improving their gait. Further, in a data-driven analysis with sensing data from five participants, we study whether there is an observable effect on the gait during use of the system. In three out of five subjects, we observed a decrease in FoG duration distributions over the protocol days during gait-training exercises. Moreover, sensing data-driven analysis shows a decrease in FoG duration and FoG number in four out of five participants when they use the system as a gait-assistive tool during normal daily life activities at home.

Background. Cognitive function is generally evaluated based on testing in the clinic, but this may not always reflect real-life function. We tested whether parameters derived from long-term, continuous monitoring of gait are associated with cognitive function in patients with Parkinson’s disease (PD).Methods. 107 patients with PD (age: 64.9 ± 9.3 yrs; UPDRS motor sum “off”: 40.4 ± 13.2; 25.23% women) wore a 3D accelerometer on their lower back for 3 days. Computerized measures of global cognitive function, executive function, attention, and nonverbal memory were assessed. Three-day acceleration derived measures included cadence, variability, bilateral coordination, and dynamic postural control. Associations between the acceleration derived measures and cognitive function were determined.Results. Linear regression showed associations between vertical gait variability and cadence and between global cognitive score, attention, and executive function (p≤0.048). Dynamic postural control was associated with global cognitive score and attention (p≤0.027). Nonverbal memory was not associated with the acceleration-derived measures.Conclusions. These findings suggest that metrics derived from a 3-day worn body-fixed sensor reflect cognitive function, further supporting the idea that the gait pattern may be altered as cognition declines and that gait provides a window into cognitive function in patients with PD.

Background Obstacle negotiation is a daily activity that requires the integration of sensorimotor and cognitive information. Recent studies provide evidence for the important role of prefrontal cortex during obstacle negotiation. We aimed to explore the effects of obstacle height and available response time on prefrontal activation. Methods Twenty healthy young adults (age: 30.1 ± 1.0 years; 50% women) walked in an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 50 mm and 100 mm. Prefrontal activation was measured using a functional near-infrared spectroscopy system. Kinect cameras measured the obstacle negotiation strategy. Prefrontal activation was defined based on mean level of HbO2 before, during and after obstacle negotiation and the HbO2 slope from gait initiation and throughout the task. Changes between types of obstacles were assessed using linear-mix models and partial correlation analyses evaluated the relationship between prefrontal activation and the distance between the feet as the subjects traversed the obstacles. Results Different obstacle heights showed similar changes in prefrontal activation measures (p > 0.210). However, during unanticipated obstacles, the slope of the HbO2 response was steeper (p = 0.048), as compared to anticipated obstacles. These changes in prefrontal activation during negotiation of unanticipated obstacles were correlated with greater distance of the leading foot after the obstacles (r = 0.831, p = 0.041). Conclusions These findings are the first to show that the pattern of prefrontal activation depends on the nature of the obstacle. More specifically, during unanticipated obstacles the recruitment of the prefrontal cortex is faster and greater than during negotiating anticipated obstacles. These results provide evidence of the important role of the prefrontal cortex and the ability of healthy young adults to tailor the activation pattern to different types of obstacles.

Eye movements are impaired by Parkinson's disease (PD) although limited research has explored if PD affects the relevance of visual fixations when walking. Visual fixations may provide crucial contextual information for safe navigation and important insights into fall risk. This study aimed to: investigate visual fixations made while walking under a range of conditions in PD; identify their task relevance; and explore their relationship with clinical features. Thirty-eight people with mild-moderate PD and forty age-matched control participants completed a straight walk with (i) no additional stimuli and (ii) with additional stimuli (visual cues or a high contrast obstacle), whilst wearing a mobile eye-tracker. Fixations were extracted and classified by location and relevance. PD participants made proportionally fewer task-relevant fixations (floor, walls and additional stimuli ahead), caused by significantly more task-irrelevant fixations (floor, walls and ceiling away from waking path) during normal walking (p = 0.014). These group differences were not apparent with visual cues (p = 0.359). During obstacle crossing trials, PD made significantly more task-relevant fixations than controls (p = 0.007). Reduced bilateral visual acuity was associated with fewer fixations in PD. Our findings suggest that people with PD visually explore complex environments less efficiently likely owing to underlying PD pathology. Visual exploration improved with the addition of salient stimuli (for example visual cues or an obstacle) and thus developing and optimising visual interventions could prove critical to improving locomotor safety and reducing falls risk in home environments.

Background/Study Context: Mobility limitations affect more than 25% of adults aged 70 years or older. This study tested the hypothesis that impairments in ankle and shoulder coordination are associated with mobility limitations among older adults.his study consisted of conducted a cross-sectional analysis from a sample of community-dwelling older adults (N = 130) aged ≥67 years. Motion capture equipment was used to collect kinematic data during rhythmic antiphase coordination of the right and left: (a) ankles moving in dorsi-plantarflexion; and (b) glenohumeral ("shoulder") moving in flexion-extension while paced by an auditory metronome. Coordination variability was measured as the standard deviation of the relative phase between right and left body segments. Mobility limitations were defined as a score of ≤9 on the Short Physical Performance Battery (SPPB). Odds ratios for mobility limitations as a function of coordination variability quartiles were determined using multivariable logistic regression.Adjusting for age, gender, body mass index, number of chronic conditions and Mini-Mental State Examination score, the odds ratios for mobility limitation (SPPB score ≤9) were 7.38 (95% confidence interval [CI]: 2.20-24.78) and 15.40 (95% CI: 4.31-55.07) for the 3rd and 4th (the poorest) ankle coordination quartiles, respectively, and 6.73 (95% CI: 2.11-21.51) for the 4th shoulder coordination quartile, compared with the best (the 1st) coordination quartiles.The results supported the hypothesis that impaired interlimb ankle and shoulder coordination are associated with the manifestation of mobility limitations. These findings indicate the need for further study of the role of coordination impairments as potential contributors to poor mobility among older adults.

Falls are a major determinant of poor quality of life, immobilization, and reduced life expectancy in people affected by Parkinson's disease (PD) and in older adults more generally. Although many questions remain, recent research has advanced the understanding of this complex problem. The goal of this review is to condense new knowledge of falls in PD from prodromal to advanced disease, taking into account risk factors, assessment, and classification as well as treatment. The fundamental steps of clinical and research-based approaches to falls are described, namely, the identification of fall risk factors, clinical and instrumental methods to evaluate and classify fall risk, and the latest evidence to reduce or delay falls in PD. We summarize recent developments, the direction in which the field should be heading, and what can be recommended at this stage. We also provide a practical algorithm for clinicians.© 2017 International Parkinson and Movement Disorder Society.

Tripping over an obstacle is one of the most common causes of falls among older adults. However, the effects of aging, obstacle height and anticipation time on negotiation strategies have not been systematically evaluated.Twenty older adults (ages: 77.7±3.4years; 50% women) and twenty young adults (age: 29.3±3.8years; 50% women) walked through an obstacle course while negotiating anticipated and unanticipated obstacles at heights of 25mm and 75mm. Kinect cameras captured the: (1) distance of the subject's trailing foot before the obstacles, (2) distance of the leading foot after the obstacles, (3) clearance of the leading foot above the obstacles, and (4) clearance of the trailing foot above the obstacles. Linear-mix models assessed changes between groups and conditions.Older adults placed their leading foot closer to the obstacle after landing, compared to young adults (p0.001). This pattern was enhanced in high obstacles (group*height interaction, p=0.033). Older adults had lower clearance over the obstacles, compared to young adults (p=0.007). This was more pronounced during unanticipated obstacles (group*ART interaction, p=0.003). The distance of the leading foot and clearance of the trailing foot after the obstacles were correlated with motor, cognitive, and functional abilities.These findings suggest that there are age-related changes in obstacle crossing strategies that are dependent on the specific characteristics of the obstacle. The results have important implications for clinical practice, suggesting that functional exercise should include obstacle negotiation training with variable practice of height and available response times. Further studies are needed to better understand the effects of motor and cognitive abilities.

With aging, walking becomes more and more of a conscious effort. Chronic pain in older adults contributes to gait limitations and falls possibly by drawing attention away from the task of walking, leading to slow gait and gait variability. We studied 249 adults aged 71-99y (mean=83.9y, 64.7%female) in the MOBILIZE Boston Study II to evaluate the potential mediating role of attention in the relation between pain and gait performance. Attention was assessed using the Test for Everyday Attention (TEA), measuring selective attention, sustained attention and attentional switching. Gait speed and variability were measured using a gait mat (CIR Systems, Inc., Franklin, NJ). Means adjusted for age, sex and education were derived from GLM models. Mediation was assessed comparing direct and indirect effects of joint pain on gait performance by adding TEA measures to the models. Gait was slower among those with multisite pain compared to single site or no pain (mean gait speed, 0.77 ± 0.02ms in multisite pain, 0.8 ± 0.03ms in single site pain, 0.92 ± 0.02ms in no pain, p-value

Functional near infra-red spectroscopy (fNIRS) is an emerging neuroimaging technique that can be applied in situations that involve movement (i.e., walking/exercise) to examine brain activity in the pre-frontal cortex during walking. Investigations using fNIRS to study the role of the pre-frontal cortex during gait in healthy young, healthy older adults, and patients with neurodegenerative disease will be presented. The results demonstrate that different patterns of frontal activation are observed during walking in aging and disease. In addition, the recruitment and activation of this “cognitive” brain region appears to be related to the complexity of the walking task, at least in healthy adults. These findings support the role of the pre-frontal cortex in the regulation of even normal walking in aging and neurodegeneration and its increasing importance during challenging gait conditions.

Parkinson’s disease (PD) is traditionally classified into the postural instability gait difficulty (PIGD) and the tremor dominant (TD) sub-types. Mild cognitive deficits are increasingly recognized as a common non-motor symptom in PD, however, cognitive differences among the two motor sub-types have not been well-described. We investigated whether changes over time in cognitive functions differ across the PIGD and TD sub-types. 57 non-demented patients with PD who were previously classified into PIGD (n=30) and TD (n=27) were followed for an average of 60 months. At baseline and follow-up, participants underwent cognitive testing (on medications): the Montreal Cognitive Assessment (MoCA) and a computerized neuropsychological battery (NeuroTrax™) that generated index scores of executive function (EF), attention, memory, and a global cognitive score. At baseline, the groups were similar with respect to age (PIGD: 69.31 ± 7.6 yrs; TD: 70.5 ± 12 yrs; p=0.652), disease duration (PIGD: 10.6 ± 3.8 yrs, TD: 10.1 ± 2.9; p=0.628), and all cognitive functions (p>0.29). At follow-up, the global cognitive score declined by 9.5% in the PIGD group (from: 94.5 ± 11.7 to 85.3 ± 13.6, p

The subthalamic nucleus (STN) is the main target for neurosurgical treatment of motor signs of Parkinson’s disease (PD). Despite the therapeutic effect on both upper and lower extremities, its role in motor control and coordination and its changes in Parkinson’s disease are not fully clear. We intraoperatively recorded single unit activity in ten patients with PD who performed repetitive feet or hand movements while undergoing implantation of a deep brain stimulator. We found both distinct and overlapping representations of upper and lower extremity movement kinematics in subthalamic units and observed evidence for re-routing to a multi-limb representation that participates in limb coordination. The well-known subthalamic somatotopy showed a large overlap of feet and hand representations in the PD patients. This overlap and excessive amounts of kinematics or coordination units may reflect pathophysiology or compensatory mechanisms. Our findings thus explain, at the single neuron level, the important subthalamic role in motor control and coordination and indicate the effect of PD on the neuronal representation of movement.

Freezing of Gait (FOG) is one of the most debilitating gait impairments in Parkinson’s disease (PD), leading to increased fall risk and reduced health-related quality of life. The utility of parkinsonian medications is often limited in the case of FOG and it frequently becomes dopamine resistant. Recent studies have suggested that pre-frontal cortex (PFC) dysfunction contributes to FOG; however, most previous findings provide only indirect evidence. To better understand the role of the PFC, we aimed to investigate the impact of high frequency, deep, repetitive transcranial magnetic stimulation (drTMS) of the medial PFC on FOG and its mediators. Nine patients with advanced PD participated in a randomized, cross-over exploratory study. We applied drTMS over the medial PFC for 16 weeks, with real and sham conditions; each condition included an intensive (i.e., 3 times a week) phase and a maintenance (once a week) phase. Scores on a FOG-provoking test, the motor part of the Unified Parkinson’s Disease Rating Scale, and gait variability significantly improved after real drTMS, but not after the sham condition. Self-report of FOG severity and cognitive scores did not improve. Due to discomfort and pain during treatment, two patients dropped out and the study was halted. These initial findings support the cause-and-effect role of the pre-frontal cortex in FOG among patients with PD. Due to the small sample size, findings should be interpreted cautiously. Further studies are needed to more fully assess the role of the medial PFC in the underlying mechanism of FOG and the possibility of using non-invasive brain stimulation to modify FOG.