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Background: Dementia is characterized by a cognitive decline in memory and other domains that lead to functional impairments. As people age, subjective memory complaints (SMC) become common, where individuals perceive cognitive decline without objective deficits on assessments. SMC can be an early sign and may precede amnestic mild cognitive impairment (MCI), which frequently advances to Alzheimer's disease (AD). Objective: This study aims to investigate white matter microstructure in individuals with SMC, in cognitively impaired (CI) cohorts, and in cognitively normal individuals using diffusion kurtosis imaging (DKI) and free water imaging (FWI). The study also explores voxel-based correlations between DKI/FWI metrics and cognitive scores to understand the relationship between brain microstructure and cognitive function. Methods: Twelve healthy controls (HCs), ten individuals with SMC, and eleven CI individuals (MCI or AD) were enrolled in this study. All participants underwent MRI 3T scan and the BNI Screen (BNIS) for Higher Cerebral Functions. Results: The mean kurtosis tensor and anisotropy of the kurtosis tensor showed significant differences across the three groups, indicating altered white matter microstructure in CI and SMC individuals. The free water volume fraction (f) also revealed group differences, suggesting changes in extracellular water content. Notably, these metrics effectively discriminated between the CI and HC/SMC groups. Additionally, correlations between imaging metrics and BNIS scores were found for CI and SMC groups. Conclusions: These imaging metrics hold promise in discriminating between individuals with CI and SMC. The observed differences indicate their potential as sensitive and specific biomarkers for early detection and differentiation of cognitive decline. [ABSTRACT FROM AUTHOR]

Introduction: Manual motor problems have been reported in mild cognitive impairment (MCI) and Alzheimer's disease (AD), but the specific aspects that are affected, their neuropathology, and potential value for classification modeling is unknown. The current study examined if multiple measures of motor strength, dexterity, and speed are affected in MCI and AD, related to AD biomarkers, and are able to classify MCI or AD. Methods: Fifty-three cognitively normal (CN), 33 amnestic MCI, and 28 AD subjects completed five manual motor measures: grip force, Trail Making Test A, spiral tracing, finger tapping, and a simulated feeding task. Analyses included (1) group differences in manual performance; (2) associations between manual function and AD biomarkers (PET amyloid β, hippocampal volume, and APOE ε4 alleles); and (3) group classification accuracy of manual motor function using machine learning. Results: Amnestic MCI and AD subjects exhibited slower psychomotor speed and AD subjects had weaker dominant hand grip strength than CN subjects. Performance on these measures was related to amyloid β deposition (both) and hippocampal volume (psychomotor speed only). Support vector classification well-discriminated control and AD subjects (area under the curve of 0.73 and 0.77, respectively) but poorly discriminated MCI from controls or AD. Conclusion: Grip strength and spiral tracing appear preserved, while psychomotor speed is affected in amnestic MCI and AD. The association of motor performance with amyloid β deposition and atrophy could indicate that this is due to amyloid deposition in and atrophy of motor brain regions, which generally occurs later in the disease process. The promising discriminatory abilities of manual motor measures for AD emphasize their value alongside other cognitive and motor assessment outcomes in classification and prediction models, as well as potential enrichment of outcome variables in AD clinical trials. [ABSTRACT FROM AUTHOR]

Background: Despite reports of gross motor problems in mild cognitive impairment (MCI) and Alzheimer's disease (AD), fine motor function has been relatively understudied. Objective: We examined if finger tapping is affected in AD, related to AD biomarkers, and able to classify MCI or AD. Methods: Forty-seven cognitively normal, 27 amnestic MCI, and 26 AD subjects completed unimanual and bimanual computerized tapping tests. We tested 1) group differences in tapping with permutation models; 2) associations between tapping and biomarkers (PET amyloid-β, hippocampal volume, and APOEɛ4 alleles) with linear regression; and 3) the predictive value of tapping for group classification using machine learning. Results: AD subjects had slower reaction time and larger speed variability than controls during all tapping conditions, except for dual tapping. MCI subjects performed worse than controls on reaction time and speed variability for dual and non-dominant hand tapping. Tapping speed and variability were related to hippocampal volume, but not to amyloid-β deposition or APOEɛ4 alleles. Random forest classification (overall accuracy = 70%) discriminated control and AD subjects, but poorly discriminated MCI from controls or AD. Conclusions: MCI and AD are linked to more variable finger tapping with slower reaction time. Associations between finger tapping and hippocampal volume, but not amyloidosis, suggest that tapping deficits are related to neuropathology that presents later during the disease. Considering that tapping performance is able to differentiate between control and AD subjects, it can offer a cost-efficient tool for augmenting existing AD biomarkers. [ABSTRACT FROM AUTHOR]

Motor performance is classically described as improving nonlinearly with practice, demonstrating rapid improvements early in practice with stabilization later, which is commonly modeled by exponential decay functions. However, retrospective analyses of our previously collected data challenge this theoretical model of motor skill acquisition, suggesting that a majority of individual learners actually demonstrate patterns of motor improvement different from this classical model. A convenience sample of young adults, older adults, and people with Parkinson disease trained on the same functional upper-extremity task. When fitting three-parameter exponential decay functions to individual participant data, the authors found that only 13.3% of young adults, 40.9% of older adults, and 66.7% of adults with Parkinson disease demonstrated this "classical" skill acquisition pattern. Thus, the three-parameter exponential decay pattern may not well-represent individuals' skill acquisition of complex motor tasks; instead, more individualized analysis methods may be warranted for advancing a theoretical understanding of motor skill acquisition. [ABSTRACT FROM AUTHOR]

There have been recent advances in the application of online games that assess motor skill acquisition/learning and its relationship to age and biological sex, both of which are associated with dementia risk. While this online motor learning assessment (called Super G), along with other computer-based cognitive tests, was originally developed to be completed on a computer, many people (including older adults) have been shown to access the internet through a mobile device. Thus, to improve the generalizability of our online motor skill learning game, it must not only be compatible with mobile devices but also yield replicable effects of various participant characteristics on performance relative to the computer-based version. It is unknown if age and sex differentially affect game performance as a function of device type (keyboard versus touchscreen control). Thus, the purpose of this study was to investigate if device type modifies the established effects of age and sex on performance. Although there was a main effect of device on performance, this effect did not alter the overall relationship between performance vs. age or sex. This establishes that Super G can now effectively be extended to both computer and mobile platforms to further test for dementia risk factors. [ABSTRACT FROM AUTHOR]

There is high inter-individual variability in motor skill learning among older adults. Identifying the nature of these individual differences remains challenging due to interactions between participant characteristics (e.g., age, cognition) and task-related factors (e.g., nature of task, level of skill pre-training), making it difficult to determine plausibly causal relationships. This study addresses these competing explanations by using mediation analysis to examine plausible causal inference between visuospatial memory and one-month retention of both gross and fine motor components of a functional upper-extremity task following training. Results suggest that better visuospatial memory results in more retention of fine but not gross motor skill, expanding on previous correlational studies in older adults and informing future interventions for maximizing motor learning in geriatric populations. [ABSTRACT FROM AUTHOR]

Skill retention is important for motor rehabilitation outcomes. Recent work has demonstrated that delayed visuospatial memory performance may predict motor skill retention in older and neuropathological populations. White matter integrity between parietal and frontal cortices may explain variance in upper-extremity motor learning tasks and visuospatial processes. We performed a whole-brain analysis to determine the white matter correlates of delayed visuospatial memory and one-week motor skill retention in nondemented older adults. We hypothesized that better frontoparietal tract integrity would be positively related to better behavioral performance. Nineteen participants (age>58) completed diffusion-weighted imaging, then a clinical test of delayed visuospatial memory and 50 training trials of an upper-extremity motor task; participants were retested on the motor task one week later. Principal component analysis was used to create a composite score for each participant's behavioral data, i.e. shared variance between delayed visuospatial memory and motor skill retention, which was then entered into a voxel-based regression analysis. Behavioral results demonstrated that participants learned and retained their skill level after a week of no practice, and their delayed visuospatial memory score was positively related to the extent of skill retention. Consistent with previous work, neuroimaging results indicated that regions within bilateral anterior thalamic radiations, corticospinal tracts, and superior longitudinal fasciculi were related to better delayed visuospatial memory and skill retention. Results of this study suggest that the simple act of testing for specific cognitive impairments prior to therapy may identify older adults who will receive little to no benefit from the motor rehabilitation regimen, and that these neural regions may be potential targets for therapeutic intervention. [ABSTRACT FROM AUTHOR]

ABSTRACT. The purpose of this study was to examine the mechanisms underlying control of distance during multijoint movements in different directions. The findings revealed 2 sequential muscle torque impulses, which [...]

Learning declines with age. Recent evidence indicates that the brainstem may play an important role in learning and motor skill acquisition. Our objective was to determine if delays in the reticular formation, measured via the startle reflex, correspond to age-related deficits in learning and retention. We hypothesized that delays in the startle reflex would be linearly correlated to learning and retention deficits in older adults. To determine if associations were unique to the reticulospinal system, we also evaluated corticospinal contributions with transcranial magnetic stimulation. Our results showed a linear relationship between startle onset latency and percent learning and retention but no relationship between active or passive motor-evoked potential onsets or peak-to-peak amplitude. These results lay the foundation for further study to evaluate if (1) the reticular formation is a subcortical facilitator of skill acquisition and (2) processing delays in the reticular formation contribute to age-related learning deficits. [ABSTRACT FROM AUTHOR]

Cortical amyloid deposition is one of the hallmark biomarkers of Alzheimer's disease (AD). However, given how cost- and timeintensive amyloid imaging can be, there is a continued need for a low-cost, non-invasive, and accessible enrichment strategy to pre-screen individuals for their likelihood of amyloid prior to imaging. Previous work supports the use of coordinated limb movement as a potential screening tool, even after controlling for cognitive and daily function. Thirty-six patients diagnosed with amnestic mild cognitive impairment over the age of 65 underwent 18F-Flutemetamol amyloid-positron emission tomography (PET) imaging and then completed a timed motor task involving upper limb coordination. This task takes ∼5 minutes to administer and score. Multivariate linear regression and receiver operator characteristic analyses showed that including motor task performance improved model prediction of amyloid burden. Results support the rationale for including functional upper extremity motor assessment as a cost- and time-effective means to screen participants for amyloid deposition. [ABSTRACT FROM AUTHOR]

Deficits in sequence-specific learning (SSL) may be a product of Parkinson's disease (PD) but this deficit could also be related to dopamine replacement. The purpose of this study was to determine whether dopamine replacement affected acquisition and retention of a standing Continuous Tracking Task in individuals with PD. SSL (difference between random/repeated Root Mean Square Error across trials) was calculated over 2 days of practice and 1 day of retention for 4 groups; 10 healthy young (HY), 10 healthy elders, 10 individuals with PD on, 9 individuals with PD off their usual dosage of dopamine replacement. Improvements in acquisition were observed for all groups; however, only the HY demonstrated retention. Therefore, age appeared to have the largest effect on SSL with no significant effect of medication. Additional research is needed to understand the influence of factors such as practice amount, task difficulty, and dopamine replacement status on SSL deficits during postural tasks. [ABSTRACT FROM AUTHOR]

Background: There is a growing body of literature that suggests that motor learning may be indicative of Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD). For example, motor learning may provide unique information for enriching clinical trials in MCI and AD if it is related to biomarkers of interest. The current study sought to examine motor learning patterns relative to amyloid deposition in the brain. Method: One hundred fifty‐four older adults who were cognitively intact or had amnestic MCI or mild AD participated. Each participant completed a motor learning task that consisted of six trials of moving beans with a spoon between three cups, and the total time to complete the task was measured. This task was repeated at two additional visits, about one week and one year later. Each participant also completed an amyloid positron emission tomography (PET) scan within a month of the motor testing. Based on FDA‐approved prescribing and visual interpretation information, the amyloid PET scan was classified as positive (n = 94) or negative (n = 60). A second repeated‐measures analysis examined trial one at the initial, one‐week, and one‐year visits to look for between‐session changes based on amyloid status. Result: Within the initial visit, both groups significantly improved their response time on this motor learning task across the six trials (p<0.001) and those classified as amyloid negative performed significantly faster than their amyloid positive peers (p = 0.01). However, there was no significant time by amyloid status interaction (p = 0.92). Like in the within‐session results, there were main effects of time (p<0.001) and amyloid status (p = 0.003), but there was not a significant interaction of the two (p = 0.37). Conclusion: Older individuals who are amyloid positive performed worse on this motor learning task than their amyloid negative peers, both within the same session and between sessions. Additionally, notable learning was present in both groups within the same session, but this was somewhat reduced in the amyloid positive individuals across sessions. Even though there was no clear interaction between time and amyloid status, motor learning tasks may provide unique information in identifying individuals for clinical trials who are more likely to be amyloid positive. [ABSTRACT FROM AUTHOR]

COVID-19 has impacted the ability to evaluate motor function in older adults, as motor assessments typically require face-to-face interaction. One hundred seventy-seven older adults nationwide completed an unsupervised functional upper-extremity assessment at home. Data were compared to data from an independent sample of community-dwelling older adults (N = 250) assessed in lab. The effect of age on performance was similar between the in-lab and at-home groups. Practice effects were also similar. Assessing upper-extremity motor function remotely is feasible and reliable in community-dwelling older adults. This test offers a practical solution for telehealth practice and other research involving remote or geographically isolated individuals. [ABSTRACT FROM AUTHOR]

Motor learning is fundamental to motor rehabilitation outcomes. There is growing evidence from non-neurological populations supporting the role of visuospatial memory function in motor learning, but current predictive models of motor recovery of individuals with stroke generally exclude cognitive measures, thereby overlooking the potential link between motor learning and visuospatial memory. Recent work has demonstrated that a clinical test of visuospatial memory (Rey-Osterrieth Complex Figure Delayed Recall) may predict 1-month skill learning in older adults; however, whether this relationship persists in individuals with chronic stroke remains unknown. The purpose of this short report was to validate previous findings using Rey-Osterrieth Complex Figure Delayed Recall test scores to predict motor learning and determine if this relationship generalized to a set of individuals post-stroke. Two regression models (one including Delayed Recall scores and one without) were trained using data from non-stroke older adults. To determine the extent to which Delayed Recall test scores impacted prediction accuracy of 1-month skill learning in older adults, we used leave-one-out cross-validation to evaluate the prediction error between models. To test if this predictive relationship generalized to individuals with chronic ischemic stroke, we then tested each trained model on an independent stroke dataset. Results indicated that in both stroke and older adult datasets, inclusion of Delayed Recall scores explained significantly more variance of 1-month skill performance than models that included age, education, and baseline motor performance alone. This proof-of-concept suggests that the relationship between delayed visuospatial memory and 1-month motor skill performance generalizes to individuals with chronic stroke, and supports the idea that visuospatial testing may provide prognostic insight into clinical motor rehabilitation outcomes. [ABSTRACT FROM AUTHOR]

Older adults often experience difficulties comprehending speech in noisy backgrounds, which hearing loss does not fully explain. It remains unknown how cognitive abilities, brain networks, and age-related hearing loss may uniquely contribute to speech in noise comprehension at the sentence level. In 31 older adults, using cognitive measures and resting-state fMRI, we investigated the cognitive and neural predictors of speech comprehension with energetic (broadband noise) and informational masking (multi-speakers) effects. Better hearing thresholds and greater working memory abilities were associated with better speech comprehension with energetic masking. Conversely, faster processing speed and stronger functional connectivity between frontoparietal and language networks were associated with better speech comprehension with informational masking. Our findings highlight the importance of the frontoparietal network in older adults' ability to comprehend speech in multi-speaker backgrounds, and that hearing loss and working memory in older adults contributes to speech comprehension abilities related to energetic, but not informational masking. [ABSTRACT FROM AUTHOR]

Objective: Grip strength is a widely used motor assessment in ageing research and has repeatedly been shown to be associated with cognition. It has been proposed that grip strength could enhance cognitive screening in experimental or clinical research, but this study uses multiple data-driven approaches to caution against this interpretation. Furthermore, we introduce an alternative motor assessment, comparable to grip dynamometry, but has a more robust relationship with cognition among older adults.Design: Associations between grip strength and cognition (measured with the Montreal Cognitive Assessment) were analysed cross sectionally using multivariate regression in two datasets: (1) The Irish LongituDinal Study on Ageing (TILDA; N = 5,980, community-dwelling adults ages 49-80) and (2) an experimental dataset (N = 250, community-dwelling adults aged 39-98). Additional statistical simulations on TILDA tested how ceiling effects or skewness in these variables influenced these associations for quality control.Results: Grip strength was significantly but weakly associated with cognition, consistent with previous studies. Simulations revealed this was not due to skewness/ceiling effects. Conversely, a new alternative motor assessment (functional reaching [FR]) had a stronger, more robust and more sensitive relationship with cognition compared to grip strength.Conclusions: Grip strength should be cautiously interpreted as being associated with cognition. However, FR may have a stronger and clinically useful relationship with cognition. [ABSTRACT FROM AUTHOR]

Although many daily activities that require the upper extremity are performed in standing, arm motor function is generally measured in sitting. The purpose of this study was to examine the effect of standing on a measure of upper extremity function, the Jebsen Hand Function Test (JHFT). Twelve nondisabled adults (26.3 ± 3.1 years) completed the JHFT with the right and left arms under two conditions: sitting and standing. Total time to complete the JHFT increased when performed in standing compared with sitting in both arms (p =.005); mean increase was 4.4% and 5.6% for the right and left arms, respectively. Checker stacking was the only subtest that showed a significant increase in completion time in standing for both arms (p =.001); card turning showed an increase for the left arm only (p =.002). Measurement of upper extremity function in standing may provide insight into arm motor capacity within the context of standing postural control demands. [ABSTRACT FROM AUTHOR]

Between-group comparisons of older and younger adults suggest that motor learning decreases with advancing age. However, such comparisons do not necessarily account for group differences in cognitive function, despite the co-occurrence of aging and cognitive decline. As such, cognitive differences may explain the observed age effects on motor learning. Recent work has shown that the extent to which a motor task is learned is related to visuospatial function in adults over age 65. The current study tested whether this relationship is replicable across a wider age range and with a brief, widely available cognitive test. Thirty-three adults (aged 39–89 years old) completed the Montreal Cognitive Assessment (MoCA) prior to practicing a functional upper extremity motor task; performance on the motor task was assessed 24 hours later to quantify learning. Backward elimination stepwise linear regression identified which cognitive domains significantly predicted retention. Consistent with previous findings, only the Visuospatial/Executive subtest score predicted change in performance 24 hours later, even when accounting for participant age. Thus, the age-related declines in motor learning that have been reported previously may be explained in part by deficits in visuospatial function that can occur with advancing age. [ABSTRACT FROM AUTHOR]

A large proportion of older adults experience hearing loss. Yet, the impact of hearing loss on the aging brain, particularly on large-scale brain networks that support cognition and language, is relatively unknown. We used resting-state functional magnetic resonance imaging (fMRI) to identify hearing loss-related changes in the functional connectivity of primary auditory cortex to determine if these changes are distinct from age and cognitive measures known to decline with age (e.g., working memory and processing speed). We assessed the functional connectivity of Heschl's gyrus in 31 older adults (60–80 years) who expressed a range of hearing abilities from normal hearing to a moderate hearing loss. Our results revealed that both left and right Heschl's gyri were significantly connected to regions within auditory, sensorimotor, and visual cortices, as well as to regions within the cingulo-opercular network known to support attention. Participant age, working memory, and processing speed did not significantly correlate with any connectivity measures once variance due to hearing loss was removed. However, hearing loss was associated with increased connectivity between right Heschl's gyrus and the dorsal anterior cingulate in the cingulo-opercular network even once variance due to age, working memory, and processing speed was removed. This greater connectivity was not driven by high frequency hearing loss, but rather by hearing loss measured in the 0.5–2 kHz range, particularly in the left ear. We conclude that hearing loss-related differences in functional connectivity in older adults are distinct from other aging-related differences and provide insight into a possible neural mechanism of compensation for hearing loss in older adults. [ABSTRACT FROM AUTHOR]

This study investigated whether grip type and/or task goal influenced reaching and grasping performance in poststroke hemiparesis. Sixteen adults with poststroke hemiparesis and twelve healthy adults reached to and grasped a cylindrical object using one of two grip types (3-finger or palmar) to achieve one of two task goals (hold or lift). Performance of the stroke group was characteristic of hemiparetic limb movement during reach-to-grasp, with more curved handpaths and slower velocities compared with the control group. These effects were present regardless of grip type or task goal. Other measures of reaching (reach time and reach velocity at object contact) and grasping (peak thumb-index finger aperture during the reach and peak grip force during the grasp) were differentially affected by grip type, task goal, or both, despite the presence of hemiparesis, providing new evidence that changes in motor patterns after stroke may occur to compensate for stroke-related motor impairment. [ABSTRACT FROM AUTHOR]

The Jebsen Hand Function Test (JHFT) is a standardized assessment that has been used as a clinical outcome measure. To appropriately interpret the effects of an intervention on hand function (as measured by the JHFT), the extent to which this instrument shows significant practice effects must be quantified. The purpose of this study was to determine whether the JHFT is susceptible to within-session practice effects. The results showed that the dominant and nondominant hands significantly improved on the JHFT and many of its subtests over six consecutive trials. Although practice effects might complicate the interpretation of change due to intervention, we briefly relate our findings to emerging neuropsychological evidence that practice effects may indicate a person's motor learning potential or treatment responsiveness. [ABSTRACT FROM AUTHOR]

The ability of the classic startle reflex to evoke voluntarily prepared movement involuntarily has captured the attention of neuroscientists for its wide-ranging functional utility and potential uses in patient populations. To date, there is only one documented task resistant to the startReact phenomenon–index finger abduction. Previous reports have suggested the lack of startReact is due to different neural mechanisms driving individuated finger movement and more proximal joint control (e.g. elbow, wrist movement). However, an alternative hypothesis exists. Though not particularly difficult to execute, isolated index finger abduction is rarely performed during activities of daily living and is not a natural correlate to common individuated finger tasks. We propose that startReact can be evoked during individuated finger movements but only during tasks that are highly trained or familiar. The objective of this study was to determine the impact of a 2-week training regimen on the ability to elicit startReact. We found evidence in support of our hypothesis that following training, individuated movements of the hands (specifically index finger abduction) become susceptible to startReact. This is significant not only because it indicates that individuated finger movements are in fact amenable to startReact, but also that startle has differential response characteristics in novel tasks compared to highly trained tasks suggesting that startle is a measurable behavioral indicator of motor learning. [ABSTRACT FROM AUTHOR]

Objectives: Long-term monitoring of concussion recovery requires time- and cost-effective methods. Physiologic complexity may be useful in evaluating visual-motor integration following concussion. The purpose of this study was to quantify the extent to which prior number of concussions influenced visual-motor tracking force complexity. Methods: Thirty-five individuals with a self-reported concussion history (age: 20.92 ± 1.98) and 15 without (age: 20.92 ± 2.21) performed an isometric visual-motor tracking task, using index finger force to trace a straight line across a computer screen. Finger force root mean square error (RMSE), multi-scale complexity, and average power from 0 to 12 Hertz (Hz) were calculated. Individual multiple regressions were fit to these outcomes. Results: Force complexity decreased linearly with an increasing number of concussions (R2 = 0.101). Males had more complex force overall (R2 = 0.219) and greater 4-8 Hz average power (R2 = 0.193). The 8-12 Hz average power decreased significantly for individuals with prior loss of consciousness (LOC) and increasing numbers of concussions (R2 = 0.143). Conclusion: Individuals exhibited linear decreases in visual-motor tracking force complexity with increasing numbers of concussions, influenced by both gender and a history of LOC. These findings indicate cumulative changes in the ways in which previously concussed individuals process and integrate visual information to guide behaviour. [ABSTRACT FROM AUTHOR]

Objective: Fine motor ability (FMA) is essential in certain activities of daily living (ADL) and is considered mostly as a component of physical function. We hypothesize that cognitive ability explains significant variance in ADL-related FMA, above and beyond what is explained by physical ability (grip strength). Method: Origins of Variance in the Old Old Study (OCTO)Twin participants (n = 218), aged 80+ (dementia, stroke, Parkinson's disease excluded) were assessed on depressive symptoms (Center for Epidemiologic Studies-Depression Scale [CES-D]), a cognitive battery, grip strength, and FMA. Results: In a series of ordinary least squares regression models, FMA was not associated with gender or depressive symptoms, but was associated with age (marginally; β = -.164, p = .051), grip strength (β = -.381, p < .01), and one cognitive measure, perceptual speed (β = -.249, p < .01). Discussion: In nondemented older adults, cognitive speed predicts ADL-related FMA after controlling for age and physical ability. Physical rehabilitation of FMA in ADL tasks should consider the importance of cognitive ability, even in nondemented older adults. [ABSTRACT FROM AUTHOR]

Practice effects on neuropsychological tests, which are improvements in test scores due to repeated exposure to testing materials, are robust in healthy elders, but muted in older adults with cognitive disorders. Conversely, few studies have investigated practice effects on motor tasks involving procedural memory, particularly across test–retest periods exceeding 24 hours. The current study examined one-week practice effects on a novel upper extremity motor task in 54 older adults with amnestic mild cognitive impairment. Results indicate that these individuals with primary memory deficits did improve on this motor task within a brief training session as well as across one week. These practice effects were unrelated to demographic characteristics or global cognition. One-week practice effects were, however, negatively related to delayed memory function, with larger practice effects being associated with poorer delayed memory and potentially better visuospatial ability. The presence of longer term practice effects on a procedural motor task not only has implications for how longitudinal assessments with similar measures involving implicit memory might be interpreted, but may also inform future rehabilitative strategies for patients with more severe declarative memory deficits. [ABSTRACT FROM PUBLISHER]

Practice effects are improvements on cognitive tests as a result of repeated exposure to testing material. However, variability exists in the literature about whether patients with amnestic mild cognitive impairment (MCI) display practice effects, which may be partially due to the methods used to calculate these changes on repeated tests. The purpose of the current study was to examine multiple methods of assessing short-term practice effects in 58 older adults with MCI. The cognitive battery, which included tests of memory (Hopkins Verbal Learning Test–Revised and Brief Visuospatial Memory Test–Revised) and processing speed (Symbol Digit Modalities Test and Trail Making Test Parts A and B), was administered twice across one week. Dependentttests showed statistically significant improvement on memory scores (ps < .01,ds = 0.8–1.3), but not on processing speed scores. Despite this, the sample showed no clinically meaningful improvement on any cognitive scores using three different reliable change indices. Regression-based change scores did identify relatively large groups of participants who showed smaller than expected practice effects, which may indicate that this method is more sensitive in identifying individuals who may portend a declining trajectory. Practice effects remain a complex construct, worthy of continued investigation in diverse clinical conditions. [ABSTRACT FROM AUTHOR]

This experiment tested the hypothesis that interlimb transfer of motor performance depends on recruitment of motor control processes that are specialized to the hemisphere contralateral to the arm that is initially trained. Right-handed participants performed a single-joint task, in which reaches were targeted to 4 different distances. While the speed and accuracy was similar for both hands, the underlying control mechanisms used to vary movement speed with distance were systematically different between the arms: the amplitude of the initial acceleration profiles scaled greater with movement speed for the right-dominant arm, while the duration of the initial acceleration profile scaled greater with movement speed for the left-non-dominant arm. These two processes were previously shown to be differentially disrupted by left and right hemisphere damage, respectively. We now hypothesize that task practice with the right arm might reinforce left-hemisphere mechanisms that vary acceleration amplitude with distance, while practice with the left arm might reinforce right-hemisphere mechanisms that vary acceleration duration with distance. We thus predict that following right arm practice, the left arm should show increased contributions of acceleration amplitude to peak velocities, and following left arm practice, the right arm should show increased contributions of acceleration duration to peak velocities. Our findings support these predictions, indicating that asymmetry in interlimb transfer of motor performance, at least in the task used here, depends on recruitment of lateralized motor control processes. [ABSTRACT FROM AUTHOR]