Motor phenotype of decline in cognitive performance among community-dwellers without dementia: population-based study and meta-analysis

Machine learning approach to classifying declines of physical function and muscle strength associated with cognitive function in older women: gait characteristics based on three speeds

Background

The aging process is associated with a cognitive and physical declines that affects neuromotor control, memory, executive functions, and motor abilities. Previous studies have made efforts to find biomarkers, utilizing complex factors such as gait as indicators of cognitive and physical health in older adults. However, while gait involves various complex factors, such as attention and the integration of sensory input, cognitive-related motor planning and execution, and the musculoskeletal system, research on biomarkers that simultaneously considers multiple factors is scarce. This study aimed to extract gait features through stepwise regression, based on three speeds, and evaluate the accuracy of machine-learning (ML) models based on the selected features to solve classification problems caused by declines in cognitive function (Cog) and physical function (PF), and in Cog and muscle strength (MS).

Methods

Cognitive assessments, five times sit-to-stand, and handgrip strength were performed to evaluate the Cog, PF, and MS of 198 women aged 65 years or older. For gait assessment, all participants walked along a 19-meter straight path at three speeds [preferred walking speed (PWS), slower walking speed (SWS), and faster walking speed (FWS)]. The extracted gait features based on the three speeds were selected using stepwise regression.

Results

The ML model accuracies were revealed as follows: 91.2% for the random forest model when using all gait features and 91.9% when using the three features (walking speed and coefficient of variation of the left double support phase at FWS and the right double support phase at SWS) selected for the Cog+PF+ and Cog-PF- classification. In addition, support vector machine showed a Cog+MS+ and Cog-MS- classification problem with 93.6% accuracy when using all gait features and two selected features (left step time at PWS and gait asymmetry at SWS).

Conclusion

Our study provides insights into the gait characteristics of older women with decreased Cog, PF, and MS, based on the three walking speeds and ML analysis using selected gait features, and may help improve objective classification and evaluation according to declines in Cog, PF, and MS among older women.

Link among apolipoprotein E E4, gait, and cognition in neurodegenerative diseases: ONDRI study

INTRODUCTION

Apolipoprotein E E4 allele (APOE E4) and slow gait are independently associated with cognitive impairment and dementia. However, it is unknown whether their coexistence is associated with poorer cognitive performance and its underlying mechanism in neurodegenerative diseases.

METHODS

Gait speed, APOE E4, cognition, and neuroimaging were assessed in 480 older adults with neurodegeneration. Participants were grouped by APOE E4 presence and slow gait. Mediation analyses were conducted to determine if brain structures could explain the link between these factors and cognitive performance.

RESULTS

APOE E4 carriers with slow gait had the lowest global cognitive performance and smaller gray matter volumes compared to non-APOE E4 carriers with normal gait. Coexistence of APOE E4 and slow gait best predicted global and domain-specific poorer cognitive performances, mediated by smaller gray matter volume.

DISCUSSION

Gait slowness in APOE E4 carriers with neurodegenerative diseases may indicate extensive gray matter changes associated with poor cognition.

HIGHLIGHTS

APOE E4 and slow gait are risk factors for cognitive decline in neurodegenerative diseases. Slow gait and smaller gray matter volumes are associated, independently of APOE E4. Worse cognition in APOE E4 carriers with slow gait is explained by smaller GM volume. Gait slowness in APOE E4 carriers indicates poorer cognition-related brain changes.

Age and beta amyloid deposition impact gait speed, stride length, and gait smoothness while transitioning from an even to an uneven walking surface in older adults

BACKGROUND

Capturing a measure of movement quality during a complex walking task may indicate the earliest signs of detrimental changes to the brain due to beta amyloid (Aβ) deposition and be a potential differentiator of older adults at elevated and low risk of developing Alzheimer's disease. This study aimed to determine: 1) age-related differences in gait speed, stride length, and gait smoothness while transitioning from an even to an uneven walking surface, by comparing young adults (YA) and older adults (OA), and 2) if gait speed, stride length, and gait smoothness in OA while transitioning from an even to an uneven walking surface is influenced by the amount of Aβ deposition present in an OA's brain.

METHODS

Participants included 56 OA (>70 years of age) and 29 YA (25-35 years of age). In OA, Aβ deposition in the brain was quantified by PET imaging. All participants completed a series of cognitive assessments, a functional mobility assessment, and self-report questionnaires. Then participants performed two sets of walking trials on a custom-built walkway containing a mixture of even and uneven surface sections, including three trials with a grass uneven surface and three trials with a rocks uneven surface. Gait data were recorded using a wireless inertial measurement unit system. Stride length, gait speed, and gait smoothness (i.e., log dimensionless lumbar jerk) in the anteroposterior (AP), mediolateral (ML), and vertical (VT) directions were calculated for each stride. Outcomes were retained for five stride locations immediately surrounding the surface transition.

RESULTS

OA exhibited slower gait (Grass: p < 0.001; Rocks: p = 0.006), shorter strides (Grass: p < 0.001; Rocks: p = 0.008), and smoother gait (Grass AP: p < 0.001; Rocks AP: p = 0.002; Rocks ML: p = 0.02) than YA, but they also exhibited greater reductions in gait speed and stride length than YA while transitioning to the uneven grass and rocks surfaces. Within the OA group, those with greater Aβ deposition exhibited decreases in smoothness with age (Grass AP: p = 0.02; Rocks AP: p = 0.03; Grass ML: p = 0.04; Rocks ML: p = 0.03), while those with lower Aβ deposition exhibited increasing smoothness with age (Grass AP: p = 0.01; Rocks AP: p = 0.02; Grass ML: p = 0.08; Rocks ML: p = 0.07). Better functional mobility was associated with less smooth gait (Grass ML: p = 0.02; Rocks ML: p = 0.05) and with less variable gait smoothness (Grass and Rocks AP: both p = 0.04) in the OA group.

CONCLUSION

These results suggest that, relative to YA, OA may be adopting more cautious, compensatory gait strategies to maintain smoothness when approaching surface transitions. However, OA with greater Aβ deposition may have limited ability to adopt compensatory gait strategies to increase the smoothness of their walking as they get older because of neuropathological changes altering the sensory integration process and causing worse dynamic balance (i.e., jerkier gait). Functional mobility, in addition to age and Aβ deposition, may be an important factor of whether or not an OA chooses to employ compensatory strategies to prioritize smoothness while walking and what type of compensatory strategy an OA chooses.

Biological and Physical Performance Markers for Early Detection of Cognitive Impairment in Older Adults

Dementia is a major cause of poor quality of life, disability, and mortality in old age. According to the geroscience paradigm, the mechanisms that drive the aging process are also involved in the pathogenesis of chronic degenerative diseases, including dementia. The dissection of such mechanisms is therefore instrumental in providing biological targets for interventions and new sources for biomarkers. Within the geroscience paradigm, several biomarkers have been discovered that can be measured in blood and that allow early identification of individuals at risk of cognitive impairment. Examples of such markers include inflammatory biomolecules, markers of neuroaxonal damage, extracellular vesicles, and DNA methylation. Furthermore, gait speed, measured at a usual and fast pace and as part of a dual task, has been shown to detect individuals at risk of future dementia. Here, we provide an overview of available biomarkers that may be used to gauge the risk of cognitive impairment in apparently healthy older adults. Further research should establish which combination of biomarkers possesses the highest predictive accuracy toward incident dementia. The implementation of currently available markers may allow the identification of a large share of at-risk individuals in whom preventive interventions should be implemented to maintain or increase cognitive reserves, thereby reducing the risk of progression to dementia.

Effects of tai chi on postural balance and quality of life among the elderly with gait disorders: A systematic review

BACKGROUND

Tai Chi is good for improving the physical fitness of older adults. But few studies have reported the effects of Tai Chi on the postural balance and quality of life of older adults with gait disorders.

OBJECTIVE

This review aimed to assess the influence of tai chi on postural stability and quality of life in older adults with abnormal gait.

METHOD

According to the literature retrieval principles, the works published from the inception date to May 2023 were retrieved, including the following databases: PubMed, Scopus, Web of Science, China National Knowledge Infrastructure, EBSCOhost, and Google Scholar. Subsequently, literature screening and quality assessment were performed.

RESULTS

A total of 16 randomized controlled trials were included in this study, Tai Chi intervention can affect populations with Parkinson's disease (PD), no exercise, mild cognitive impairment (MCI), chronic stroke, sedentary, fear of falling, or history of falling. Postural instability is associated with balance, gait, the Unified Parkinson's Disease Rating Scale Motor Subscale 3 (UPDRS III), mobility, lower body strength, and falls. Only two articles looked at quality of life. The Yang style is the most commonly used in the intervention. Nonetheless, most studies were performed on female participants, hence, more research on older male populations is needed.

CONCLUSION

Tai Chi intervention benefits postural balance in patients with gait disorders. 12 weeks is the most common intervention period for patients with gait disorders. The frequency of intervention is seven articles twice a week, and the intervention time is about 60 minutes. The Tai Chi intervention methods in this study involve Yang Style, Sun Style, Taoist Tai Chi, and Health Qigong Tai Chi, but the Yang Style Tai Chi intervention is the most widely used.

Relationship of Neural Correlates of Gait Characteristics and Cognitive Dysfunction in Patients with Mild Cognitive Impairment

Background: Some patients with mild cognitive impairment (MCI) experience gait disturbances. However, there are few reports on the relationship between gait disturbance and cognitive function in patients with MCI. Therefore, we investigated the neural correlates of gait characteristics related to cognitive dysfunction. Methods: Eighty patients diagnosed with MCI from three dementia centers in Gangwon-do, Korea, were recruited for this study. We defined MCI as a Clinical Dementia Rating global score of 0.5 or higher, with a memory domain score of 0.5 or greater. The patients were classified as having either higher or lower MMSE and the groups were based on their Mini Mental Status Examination z-scores. Multiple logistic regression analysis was performed to examine the association between the gait characteristics and cognitive impairment. Analyses included variables such as age, sex, years of education, number of comorbidities, body mass index, and height. Results: Gait velocity, step count, step length, heel-to-heel base support, swing and stance phase duration, and support time were associated with cognitive function. A decrease in gray matter volume in the right pericalcarine area was associated with gait characteristics related to cognitive dysfunction. An increase in the curvature of gray matter in the right entorhinal, right lateral orbitofrontal, right cuneus, and right and left pars opercularis areas was also associated with gait characteristics related to cognitive dysfunction. Conclusion: Since gait impairment is an important factor in determining activities of daily living in patients with mild cognitive impairment, the evaluation of gait and cognitive functions in patients with mild cognitive impairment is important.

Minding your steps: a cross-sectional pilot study using foot-worn inertial sensors and dual-task gait analysis to assess the cognitive status of older adults with mobility limitations

BACKGROUND

Cognitive impairment is a critical aspect of our aging society. Yet, it receives inadequate intervention due to delayed or missed detection. Dual-task gait analysis is currently considered a solution to improve the early detection of cognitive impairment in clinical settings. Recently, our group proposed a new approach for the gait analysis resorting to inertial sensors placed on the shoes. This pilot study aimed to investigate the potential of this system to capture and differentiate gait performance in the presence of cognitive impairment based on single- and dual-task gait assessments.

METHODS

We analyzed demographic and medical data, cognitive tests scores, physical tests scores, and gait metrics acquired from 29 older adults with mobility limitations. Gait metrics were extracted using the newly developed gait analysis approach and recorded in single- and dual-task conditions. Participants were stratified into two groups based on their Montreal Cognitive Assessment (MoCA) global cognitive scores. Statistical analysis was performed to assess differences between groups, discrimination ability, and association of gait metrics with cognitive performance.

RESULTS

The addition of the cognitive task influenced gait performance of both groups, but the effect was higher in the group with cognitive impairment. Multiple dual-task costs, dual-task variability, and dual-task asymmetry metrics presented significant differences between groups. Also, several of these metrics provided acceptable discrimination ability and had a significant association with MoCA scores. The dual-task effect on gait speed explained the highest percentage of the variance in MoCA scores. None of the single-task gait metrics presented significant differences between groups.

CONCLUSIONS

Our preliminary results show that the newly developed gait analysis solution based on foot-worn inertial sensors is a pertinent tool to evaluate gait metrics affected by the cognitive status of older adults relying on single- and dual-task gait assessments. Further evaluation with a larger and more diverse group is required to establish system feasibility and reliability in clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT04587895).

Using shoe-mounted inertial sensors and stepping exergames to assess the motor-cognitive status of older adults: A correlational study

Objective

Stepping exergames designed to stimulate physical and cognitive skills can provide important information concerning individuals’ performance. In this study, we investigated the potential of stepping and gameplay metrics to assess the motor-cognitive status of older adults.

Methods

Stepping and gameplay metrics were recorded in a longitudinal study involving 13 older adults with mobility limitations. Game parameters included games’ scores and reaction times. Stepping parameters included length, height, speed, and duration, measured by inertial sensors placed on the shoes while interacting with the exergames. Parameters measured on the first gameplay were correlated against standard cognitive and mobility assessments, including the Montreal Cognitive Assessment (MoCA), gait speed, and the Short Physical Performance Battery. Based on MoCA scores, patients were then stratified into two groups: cognitively impaired and healthy controls. The differences between the two groups were visually inspected, considering their within-game progression over the training period.

Results

Stepping and gameplay metrics had moderate-to-strong correlations with cognitive and mobility performance indicators: faster, longer, and higher steps were associated with better mobility scores; better cognitive games’ scores and reaction times, and longer and faster steps were associated with better cognitive performance. The preliminary visual analysis revealed that the group with cognitive impairment required more time to advance to the next difficulty level, also presenting slower reaction times and stepping speeds when compared to the healthy control group.

Conclusion

Stepping exergames may be useful for assessing the cognitive and motor status of older adults, potentially allowing assessments to be more frequent, affordable, and enjoyable. Further research is required to confirm results in the long term using a larger and more diverse sample.

Influencing factors on instrumental activities of daily living functioning in people with mild cognitive disorder - a secondary investigation of cross-sectional data

BACKGROUND

Finding a strategy to reduce the impact of cognitive decline on everyday functioning in persons suffering from cognitive impairment is a public health priority. Instrumental activities of daily living (IADL) are key to everyday functioning. Hence, it is essential to understand the influencing factors on IADL to develop specific interventions to improve everyday functioning in persons with mild cognitive disorder. Therefore, this study aimed to 1) explore different influencing factors on IADL functioning considering all domains of the International Classification of Functioning, disability, and health and 2) rank these factors.

METHODS

We performed a secondary analysis of a cohort including participants with amnestic mild cognitive impairment (a-MCI) or mild Alzheimer's Dementia (mild AD). The IADL functioning model was used as a starting point to estimate the effects of cognitive and physical function factors and personal and environmental factors on IADL functioning using multiple linear regression analysis, including subgroup analysis in persons with a-MCI. We used standardized coefficient estimates to relate the size of the predictor effects in the final model.

RESULTS

We included 105 participants (64 a-MCI, 41 mild AD); the mean age was 81.9 years (SD 4.9), with 70% females. Based on a multi-step approach and model fit, the final model included IADL functioning as the response variable and memory, attention, executive function, vision and hearing, mobility, balance, education, and social support as predictors. The final model explained 75% of the variability. The significant predictors in the model were mobility, balance, attention, and education, and were the predictors with the most considerable effects based on standardized coefficient estimates. The subgroup analysis, including only a-MCI participants, revealed a similar pattern.

CONCLUSION

Our results confirm that IADL functioning in people with mild cognitive disorder is influenced by cognitive and physical function and personal factors. The study provides further insight into understanding IADL functioning impairments in persons with mild impaired cognition and may be used to develop specific non-pharmacological interventions.

Dividing attention during the Timed Up and Go enhances associations of several subtask performances with MCI and cognition

We tested the hypothesis that dividing attention would strengthen the ability to detect mild cognitive impairment (MCI) and specific cognitive abilities from Timed Up and Go (TUG) performance in the community setting. While wearing a belt-worn sensor, 757 dementia-free older adults completed TUG during two conditions, with and without a concurrent verbal serial subtraction task. We segmented TUG into its four subtasks (i.e., walking, turning, and two postural transitions), and extracted 18 measures that were summarized into nine validated sensor metrics. Participants also underwent a detailed cognitive assessment during the same visit. We then employed a series of regression models to determine the combinations of subtask sensor metrics most strongly associated with MCI and specific cognitive abilities for each condition. We also compared subtask performances with and without dividing attention to determine whether the costs of divided attention were associated with cognition. While slower TUG walking and turning were associated with higher odds of MCI under normal conditions, these and other subtask associations became more strongly linked to MCI when TUG was performed under divided attention. Walking and turns were also most strongly associated with executive function and attention, particularly under divided attention. These differential associations with cognition were mirrored by performance costs. However, since several TUG subtasks were more strongly associated with MCI and cognitive abilities when performed under divided attention, future work is needed to determine how instrumented dual-task TUG testing can more accurately estimate risk for late-life cognitive impairment in older adults.

High Fall Risk Associated With Memory Deficit and Brain Lobes Atrophy Among Elderly With Amnestic Mild Cognitive Impairment and Mild Alzheimer's Disease

Objectives

This study aimed to primarily examine the association between memory deficit and increased fall risk, second, explore the underlying neuroanatomical linkage of this association in the elderly with aMCI and mild AD.

Methods

In this cross-sectional study, a total of 103 older adults were included (55 cognitively normal, CN; 48 cognitive impairment, CI, elderly with aMCI, and mild AD). Memory was assessed by the Auditory Verbal Learning Test (AVLT). Fall risk was evaluated by the Timed Up and Go (TUG) Test, heel strike angles, and stride speed, which were collected by an inertial-sensor-based wearable instrument (the JiBuEn™ gait analysis system). Brain volumes were full-automatic segmented and quantified using AccuBrain^® v1.2 from three-dimensional T1-weighted (3D T1W) MR images. Multivariable regression analysis was used to examine the extent of the association between memory deficit and fall risk, the association of brain volumes with memory, and fall risk. Age, sex, education, BMI, and HAMD scores were adjusted. Sensitivity analysis was conducted.

Results

Compared to CN, participants with aMCI and mild AD had poorer cognitive performance (p < 0.001), longer TUG time (p = 0.018), and smaller hippocampus and medial temporal volumes (p = 0.037 and 0.029). In the CI group, compared to good short delayed memory (SDM) performance (AVLT > 5), the elderly with bad SDM performance (AVLT ≤ 3) had longer TUG time, smaller heel strike angles, and slower stride speed. Multivariable regression analysis showed that elderly with poor memory had higher fall risk than relative good memory performance among cognitive impairment elderly. The TUG time increased by 2.1 s, 95% CI, 0.54∼3.67; left heel strike angle reduced by 3.22°, 95% CI, −6.05 to −0.39; and stride speed reduced by 0.09 m/s, 95% CI, −0.19 to −0.00 for the poor memory elderly among the CI group, but not found the association in CN group. In addition, serious medial temporal atrophy (MTA), small volumes of the frontal lobe and occipital lobe were associated with long TUG time and small heel strike angles; small volumes of the temporal lobe, frontal lobe, and parietal lobe were associated with slow stride speed.

Conclusion

Our findings suggested that memory deficit was associated with increased fall risk in the elderly with aMCI and mild AD. The association might be mediated by the atrophy of medial temporal, frontal, and parietal lobes. Additionally, increased fall risk, tested by TUG time, heel stride angles, and stride speed, might be objective and convenient kinematics markers for dynamic monitoring of both memory function and fall risk.

Timed Up and Go in People with Subjective Cognitive Decline Is Associated with Faster Cognitive Deterioration and Cortical Thickness

INTRODUCTION

Early markers of neurodegeneration provide an opportunity to detect, monitor, and initiate interventions in individuals who have an increased risk of developing dementia. Here, we investigated whether the Timed Up and Go (TUG) test is associated with early brain neurodegeneration and whether the TUG test could be a marker of cognitive decline in people with subjective cognitive decline (SCD).

METHODS

This is a longitudinal analysis of the Dementia Disease Initiation Study, a prospective, community-based, cohort study from Norway, designed to investigate early markers of cognitive impairment and dementia. Participants were classified as SCD and healthy controls (HC). The main studied variables were the TUG test and cognition as measured by the Mini-Mental State Examination and the Consortium to Establish a Registry for Alzheimer's Disease memory composite score. Additionally, we investigated the cross-sectional association of brain morphology with the TUG using 1.5T-MRI.

RESULTS

The sample included 45 participants (SCD = 21, HC = 24) followed during a mean time of 1.50 ± 0.70 years. At baseline, the cognitive performance did not differ between the groups, but TUG was longer in SCD. Slower baseline TUG was associated with a faster cognitive decline in both groups and it was also associated with reduced cortical thickness especially in motor, executive, associative, and somatosensory cortical regions in people with SCD.

DISCUSSION/CONCLUSION

TUG predicted cognitive change in individuals with SCD, and there was a negative association between TUG and cortical thickness. TUG is a promising cheap and noninvasive marker of early cognitive decline and may help initiate interventions in individuals who have an increased risk of dementia.

Correlations between Hand Dexterity and Bimanual Coordination on the Activities of Daily Living in Older Adults with Mild Cognitive Impairment

Background/Aims

Many motor impairments are present in older adults with cognitive decline. One of them is the impairment of hand dexterity and bimanual coordination that result in poor functional ability in the activities of daily living (ADL). This study investigated the effects of hand dexterity and bimanual coordination declination on the sub-domains of ADL in older adults with mild cognitive impairment (MCI).

Methods

Thirty-one senior individuals with MCI were recruited in this study. The Purdue Pegboard Test was used to measure hand dexterity, and bimanual coordination was assessed by the continuous circle-drawing task. Their ADL were assessed with the General Activity Daily Living questionnaire.

Results

The correlations analysis showed an association between the dominant hand and bimanual dexterity with the domestic domain of ADL and all conditions of hand dexterity with the complex domain of ADL. Moreover, the multiple regression analysis showed that the predictor of the greatest effect for domestic and complex domains was dominant hand dexterity.

Discussion/Conclusion

These results revealed that dominant hand dexterity strongly affected domestic and complex ADL in older adults with MCI. There were age-related changes regarding lateral asymmetrical motor reduction, especially in cognitive tasks. However, complex tasks involving cognitive function may need dominant, nondominant and bimanual hand dexterity.

Modeling Functional Limitations, Gait Impairments, and Muscle Pathology in Alzheimer's Disease: Studies in the 3xTg-AD Mice

Gait impairments in Alzheimer's disease (AD) result from structural and functional deficiencies that generate limitations in the performance of activities and restrictions in individual's biopsychosocial participation. In a translational way, we have used the conceptual framework proposed by the International Classification of Disability and Health Functioning (ICF) to classify and describe the functioning and disability on gait and exploratory activity in the 3xTg-AD animal model. We developed a behavioral observation method that allows us to differentiate qualitative parameters of psychomotor performance in animals' gait, similar to the behavioral patterns observed in humans. The functional psychomotor evaluation allows measuring various dimensions of gait and exploratory activity at different stages of disease progression in dichotomy with aging. We included male 3xTg-AD mice and their non-transgenic counterpart (NTg) of 6, 12, and 16 months of age (n = 45). Here, we present the preliminary results. The 3xTg-AD mice show more significant functional impairment in gait and exploratory activity quantitative variables. The presence of movement limitations and muscle weakness mark the functional decline related to the disease severity stages that intensify with increasing age. Motor performance in 3xTg-AD is accompanied by a series of bizarre behaviors that interfere with the trajectory, which allows us to infer poor neurological control. Additionally, signs of physical frailty accompany the functional deterioration of these animals. The use of the ICF as a conceptual framework allows the functional status to be described, facilitating its interpretation and application in the rehabilitation of people with AD.

Gait Kinematic and Kinetic Characteristics of Older Adults With Mild Cognitive Impairment and Subjective Cognitive Decline: A Cross-Sectional Study

Background

Older adults with mild cognitive impairment (MCI) have slower gait speed and poor gait performance under dual-task conditions. However, gait kinematic and kinetic characteristics in older adults with MCI or subjective cognitive decline (SCD) remain unknown. This study was designed to explore the difference in gait kinematics and kinetics during level walking among older people with MCI, SCD, and normal cognition (NC).

Methods

This cross-sectional study recruited 181 participants from July to December 2019; only 82 met the inclusion criteria and consented to participate and only 79 completed gait analysis. Kinematic and kinetic data were obtained using three-dimensional motion capture system during level walking, and joint movements of the lower limbs in the sagittal plane were analyzed by Visual 3D software. Differences in gait kinematics and kinetics among the groups were analyzed using multivariate analysis of covariance (MANCOVA) with Bonferroni post-hoc analysis. After adjusting for multiple comparisons, the significance level was p < 0.002 for MANCOVA and p < 0.0008 for post-hoc analysis.

Results

Twenty-two participants were MCI [mean ± standard deviation (SD) age, 71.23 ± 6.65 years], 33 were SCD (age, 72.73 ± 5.25 years), and 24 were NC (age, 71.96 ± 5.30 years). MANCOVA adjusted for age, gender, body mass index (BMI), gait speed, years of education, diabetes mellitus, and Geriatric Depression Scale (GDS) revealed a significant multivariate effect of group in knee peak extension angle (F = 8.77, p < 0.0001) and knee heel strike angle (F = 8.07, p = 0.001) on the right side. Post-hoc comparisons with Bonferroni correction showed a significant increase of 5.91° in knee peak extension angle (p < 0.0001) and a noticeable decrease of 6.21°in knee heel strike angle (p = 0.001) in MCI compared with NC on the right side. However, no significant intergroup difference was found in gait kinetics, including dorsiflexion, plantar flexion, knee flexion, knee extension, hip flexion, and hip extension(p > 0.002).

Conclusion

An increase of right knee peak extension angle and a decrease of right knee heel strike angle during level walking were found among older adults with MCI compared to those with NC.

Associations between gait speed and brain structure in amnestic mild cognitive impairment: a quantitative neuroimaging study

BACKGROUND

Patients with amnestic mild cognitive impairment (aMCI) present gait disturbances including slower speed and higher variability when compared to cognitively healthy individuals (CHI). Brain neuroimaging could explore higher levels of motor control. Our purpose was to look for an association between morphometrics and gait parameters in each group. We hypothesized that the relation between morphological cerebral alteration and gait speed are different following the group.

METHODS

Fifty-three participants (30 with aMCI and 23 CHI) were recruited in this French cross-sectional study (mean 72 ± 5 years, 38% female). Gait speed and gait variability (coefficients of variation of stride time (STV) and stride length (SLV)) were measured using GAITrite® system. CAT12 software was used to analyse volume and surface morphometry like gray matter volume (GMV) and cortical thickness (CT). Age, gender and education level were used as potential cofounders.

RESULTS

aMCI had slower gait speed and higher STV when compared to CHI. In aMCI the full adjusted linear regression model showed that lower gait speed was associated with decreased GMV and lower CT in bilateral superior temporal gyri (p < 0.36). In CHI, no association was found between gait speed and brain structure. Higher SLV was correlated with reduced GMV in spread regions (p < 0.05) and thinner cortex in the middle right frontal gyrus (p = 0.001) in aMCI. In CHI, higher SLV was associated with reduced GMV in 1 cluster: the left lingual (p = 0.041).

CONCLUSIONS

These findings indicate that lower gait speed is associated with specific brain structural changes as reduced GMV and CT during aMCI.

Cross-sectional associations between cognition and mobility in Parkinson's disease

Cross-sectional studies show an association of decline in mental flexibility and inhibitory control with reduced gait speed and falls, as well as divided attention deficit and difficulty in initiating gait.

Combining Multimodal Behavioral Data of Gait, Speech, and Drawing for Classification of Alzheimer's Disease and Mild Cognitive Impairment

BACKGROUND

Gait, speech, and drawing behaviors have been shown to be sensitive to the diagnosis of Alzheimer's disease (AD) and mild cognitive impairment (MCI). However, previous studies focused on only analyzing individual behavioral modalities, although these studies suggested that each of these modalities may capture different profiles of cognitive impairments associated with AD.

OBJECTIVE

We aimed to investigate if combining behavioral data of gait, speech, and drawing can improve classification performance compared with the use of individual modality and if each of these behavioral data can be associated with different cognitive and clinical measures for the diagnosis of AD and MCI.

METHODS

Behavioral data of gait, speech, and drawing were acquired from 118 AD, MCI, and cognitively normal (CN) participants.

RESULTS

Combining all three behavioral modalities achieved 93.0% accuracy for classifying AD, MCI, and CN, and only 81.9% when using the best individual behavioral modality. Each of these behavioral modalities was statistically significantly associated with different cognitive and clinical measures for diagnosing AD and MCI.

CONCLUSION

Our findings indicate that these behaviors provide different and complementary information about cognitive impairments such that classification of AD and MCI is superior to using either in isolation.

Cognition and motor function: The gait and cognition pooled index

BACKGROUND

There is a need for outcome measures with improved responsiveness to changes in pre-dementia populations. Both cognitive and motor function play important roles in neurodegeneration; motor function decline is detectable at early stages of cognitive decline. This proof of principle study used a Pooled Index approach to evaluate improved responsiveness of the predominant outcome measure (ADAS-Cog: Alzheimer's Disease Assessment Scale-Cognitive Subscale) when assessment of motor function is added.

METHODS

Candidate Pooled Index variables were selected based on theoretical importance and pairwise correlation coefficients. Kruskal-Wallis and Mann-Whitney U tests assessed baseline discrimination. Standardized response means assessed responsiveness to longitudinal change.

RESULTS

Final selected variables for the Pooled Index include gait velocity, dual-task cost of gait velocity, and an ADAS-Cog-Proxy (statistical approximation of the ADAS-Cog using similar cognitive tests). The Pooled Index and ADAS-Cog-Proxy scores had similar ability to discriminate between pre-dementia syndromes. The Pooled Index demonstrated trends of similar or greater responsiveness to longitudinal decline than ADAS-Cog-Proxy scores.

CONCLUSION

Adding motor function assessments to the ADAS-Cog may improve responsiveness in pre-dementia populations.

Screening of Parkinsonian subtle fine-motor impairment from touchscreen typing via deep learning

Fine-motor impairment (FMI) is progressively expressed in early Parkinson’s Disease (PD) patients and is now known to be evident in the immediate prodromal stage of the condition. The clinical techniques for detecting FMI may not be robust enough and here, we show that the subtle FMI of early PD patients can be effectively estimated from the analysis of natural smartphone touchscreen typing via deep learning networks, trained in stages of initialization and fine-tuning. In a validation dataset of 36,000 typing sessions from 39 subjects (17 healthy/22 PD patients with medically validated UPDRS Part III single-item scores), the proposed approach achieved values of area under the receiver operating characteristic curve (AUC) of 0.89 (95% confidence interval: 0.80–0.96) with sensitivity/specificity: 0.90/0.83. The derived estimations result in statistically significant (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$p<0.05$$\end{document}p<0.05) correlation of 0.66/0.73/0.58 with the clinical standard UPDRS Part III items 22/23/31, respectively. Further validation analysis on 9 de novo PD patients vs. 17 healthy controls classification resulted in AUC of 0.97 (0.93–1.00) with 0.93/0.90. For 253 remote study participants, with self-reported health status providing 252.000 typing sessions via a touchscreen typing data acquisition mobile app (iPrognosis), the proposed approach predicted 0.79 AUC (0.66–0.91) with 0.76/0.71. Remote and unobtrusive screening of subtle FMI via natural smartphone usage, may assist in consolidating early and accurate diagnosis of PD.

Development of a model on factors affecting instrumental activities of daily living in people with mild cognitive impairment - a Delphi study

Introduction

The level of function of instrumental activities of daily living (IADL) is crucial for a person’s autonomy. A clear understanding of the nature of IADL and its limitations in people with mild cognitive impairment (MCI) is lacking. Literature suggests numerous possible influencing factors, e.g. cognitive function, but has not considered other domains of human functioning, such as environmental factors. Our aim was to develop a comprehensive model of IADL functioning that depicts the relevant influencing factors.

Methods

We conducted a four-round online Delphi study with a sample of international IADL experts (N = 69). In the first round, panelists were asked to mention all possible relevant cognitive and physical function factors, as well as environmental and personal factors, that influence IADL functioning. In the subsequent rounds, panelists rated the relevance of these factors. Consensus was defined as: 1) ≥70% agreement between panelists on a factor, and 2) stability over two successive rounds.

Results

Response rates from the four rounds were high (83 to 100%). In the first round, 229 influencing factors were mentioned, whereof 13 factors reached consensus in the subsequent rounds. These consensual factors were used to build a model of IADL functioning. The final model included: five cognitive function factors (i.e. memory, attention, executive function, and two executive function subdomains -problem solving / reasoning and organization / planning); five physical function factors (i.e. seeing functions, hearing functions, balance, gait / mobility functions and functional mobility functions); two environmental factors (i.e. social network / environment and support of social network / environment); and one personal factor (i.e. education).

Conclusions

This study proposes a comprehensive model of IADL functioning in people with MCI. The results from this Delphi study suggest that IADL functioning is not merely affected by cognitive function factors, but also by physical function factors, environmental factors and personal factors. The multiplicity of factors mentioned in the first round also underlines the individuality of IADL functioning in people with MCI. This model may serve as a basis for future research in IADL functioning in people with MCI.

Understated Cognitive Impairment Assessed with the Clock-Drawing Test in Community-Dwelling Individuals Aged ≥50 Years

OBJECTIVES

To estimate the prevalence of understated cognitive impairment by administering the Clock-Drawing Test (CDT) to community-dwelling individuals aged ≥50 years and to investigate the associated clinical phenotype.

DESIGN

A cross-sectional analysis of baseline data on community-dwelling individuals assessed at an outpatient clinic in the Paris region of France.

SETTING AND PARTICIPANTS

Participants aged ≥50 years (n = 488, median age: 62.1 years) prospectively included in the SUCCessful agEing outpatiEnt's Department survey between 2010 and 2014.

METHODS

A multidimensional geriatric assessment, including cognition [7-point CDT, Mini-Mental State Examination (MMSE), the 5-word screening test (5-WT), and the Frontal Assessment Battery (FAB)], gait speed in dual tasks, mood [the Geriatric Depression Scale (GDS)], balance, physical functions (gait speed and handgrip strength), nutrition, bone density, and comorbidities; major cardiovascular risk factors, and Scheltens and Fazekas scores on brain magnetic resonance imaging. Baseline characteristics were analyzed as a function of the CDT score (<7 vs 7), using age-adjusted logistic models.

RESULTS

The prevalence of impairment in the CDT was 23.6%; higher than the values for the MMSE (12.7%), 5-WT (2.3%), and FAB (16.6%). In age-adjusted analyses, a lower educational level (odds ratio [95% confidence interval] = 0.72 [0.58‒0.89]), diabetes (2.57 [1.14‒5.79]), metabolic syndrome (1.93 [1.05‒3.56]), lower gait speed in the cognitive dual task (1.27 [1.05‒1.53]), a poorer Geriatric Depression Scale score (1.86 [1.04‒3.32]), a poorer MMSE score (2.56 [1.35‒4.88]), a poorer FAB score (1.79 [1.01‒3.16]), impaired episodic memory in the 5-WT (4.11 [1.12‒15.02]), and a higher Scheltens score (P = .001) were significantly associated with CDT impairment.

CONCLUSIONS AND IMPLICATIONS

Understated cognitive impairment is common among young seniors and is associated with factors known to be linked to a higher risk of cognitive decline and dementia. These findings suggest that the CDT may be of value for identifying high-risk individuals who may then benefit from targeted multidomain prevention actions (diet, exercise, cognitive training, and vascular risk factor management).

Age-specific differences in gait domains and global cognitive function in older women: gait characteristics based on gait speed modification

Background

Several studies have reported the association between gait and global cognitive function; however, there is no study explaining the age-specific gait characteristics of older women and association between those characteristics and global cognitive function by age-specific differences and gait speed modification. The aim of this study was to examine age-specific differences in gait characteristics and global cognitive function in older women as well as identify gait domains strongly associated with global cognitive function in older women based on gait speed modification.

Methods

One hundred sixty-four female participants aged 65–85 years were examined. Participants were assessed for global cognitive function through the mini-mental state examination. They also performed three trials of the overground walking test along a straight 20 m walkway. Inertial measurement unit sensors with shoe-type data loggers on both the left and right outsoles were used to measure gait characteristics.

Results

The pace at all speeds and the variability and phase at faster speeds were altered in women aged >75 years (all pace domain parameters, p < 0.05); variability and phase highly depended on age (all p < 0.05). Variability at slower speeds (β = −0.568 and p = 0.006) and the phase at the preferred (β = −0.471 and p = 0.005) and faster speeds (β = −0.494 and p = 0.005) were associated with global cognitive function in women aged >75 years.

Discussion

The variability and phase domains at faster speeds were considered to identify gait changes that accompany aging. In addition, the decreases in global cognitive function are associated with increased variability and phase domains caused by changes in gait speed in older women.

Conclusion

Our results are considered useful for understanding age-related gait characteristics with global cognitive function in old women.

Wearable Sensor-Based Daily Life Walking Assessment of Gait for Distinguishing Individuals With Amnestic Mild Cognitive Impairment

Objectives: To characterize gait disorders in patients with amnestic mild cognitive impairment (aMCIs) and determine the association between the performance of the gait function and cognition.

Methodology: In this study, we enrolled 38 patients with aMCI and 30 cognitively normal individuals normal controls (NC). Neuropsychological assessments included tests of memory, executive function, language, and attention. Using an inertial-sensor-based wearable instrument, we collected the gait data dynamically for at least 1 h/day for 2 weeks. The gait parameters included walking velocity, stride length, stride time, cadence, and stride time variability.

Results: The aMCI patients had reduced walking velocity and stride length and increased stride time variability compared with the NCs. The total number of steps, stride time, and cadence did not differ between the two groups. For all the subjects, walking velocity and stride length was positively associated with memory and executive function. Stride time variability was negatively correlated with the cognitive domains including memory, executive function and attention.

Conclusion: This study suggested that cognitive impairment-related gait disorders occur (reduced gait speed, gait length, and gait stability) in daily life walking among the aMCI patients. A sensor-based wearable device for gait measurement may be an alternative and convenient tool for screening cognitive impairment.

Two-year changes in gait variability in community-living older adults

BACKGROUND

Increases in stride-to-stride fluctuations (gait variability) are common among older adults, but little is known about the natural progression of gait variability with increasing age.

RESEARCH QUESTION

Does gait variability change with increasing age in a group of community-living older adults?

METHODS

The participants were community-living volunteers between 70-81 years, who were tested with a two-year interval between tests. They walked 6.5 m under four different conditions: At preferred speed, at fast speed, during a dual task condition and on an uneven surface. Trunk accelerations in the anteroposterior (AP), mediolateral (ML) and vertical (V) direction were captured using a body-worn sensor worn at the lower back. Gait variability was estimated using an autocorrelation procedure, where coefficients tending towards 1.0 indicated low variability and 0.0 as high variability. To estimate change, we used an ANOVA-procedure with baseline gait speed as a covariate.

RESULTS

At baseline, 85 older adults were tested, and data for 56 of these were available for analysis over a two-year period of time. The average age at inclusion was 75.8 years (SD 3.43) and 60% were women. During preferred speed walking, variability increased in the AP direction (mean difference 0.05, p = .038), during fast speed walking it increased in the V direction (mean difference 0.04, p = .037) and during dual task-walking, it increased in the ML and V directions (mean differences 0.03, p = .032 and 0.09, p = .020 respectively).

SIGNIFICANCE

The findings from this study could be helpful for discriminating between normal and pathological progression of gait variability in older adults.

Analysis of Motor Function in the Tg4-42 Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is a neurodegenerative disorder and the most common form of dementia. Hallmarks of AD are memory impairments and cognitive deficits, but non-cognitive impairments, especially motor dysfunctions are also associated with the disease and may even precede classic clinical symptoms. With an aging society and increasing hospitalization of the elderly, motor deficits are of major interest to improve independent activities in daily living. Consistent with clinical findings, a variety of AD mouse models develop motor deficits as well. We investigated the motor function of 3- and 7-month-old Tg4-42 mice in comparison to wild-type controls and 5XFAD mice and discuss the results in context with several other AD mouse model. Our study shows impaired balance and motor coordination in aged Tg4-42 mice in the balance beam and rotarod test, while general locomotor activity and muscle strength is not impaired at 7 months. The cerebellum is a major player in the regulation and coordination of balance and locomotion through practice. Particularly, the rotarod test is able to detect cerebellar deficits. Furthermore, supposed cerebellar impairment was verified by 18F-FDG PET/MRI. Aged Tg4-42 mice showed reduced cerebellar glucose metabolism in the 18F-FDG PET. Suggesting that, deficits in coordination and balance are most likely due to cerebellar impairment. In conclusion, Tg4-42 mice develop motor deficits before memory deficits, without confounding memory test. Thus, making the Tg4-42 mouse model a good model to study the effects on cognitive decline of therapies targeting motor impairments.

Gait and dementia

Cognitive decline and neurodegenerative disease have been implicated in gait dysfunction via disturbance of top-down control mechanisms. Gait velocity decreases, variability increases, and ability to multitask while walking is impaired as cognition declines. Changes in gait can be used to predict incident mild cognitive impairment states as well as dementia. Slow gait velocity together with a cognitive complaint, the Motoric Cognitive Risk syndrome, can serve as a clinical biomarker for high risk of neurologic decline. While patients with Alzheimer's disease typically have quantitative gait impairment, those with other forms of dementia often manifest more overt, qualitative changes to walking. A variety of interventions may be useful to improve gait, including physical and cognitive rehabilitation, treatment of specific underlying causes of gait problems, and treatment of the dementia itself. Understanding the relationship between gait and dementia can elucidate pathology and improve patient care.

Medical, Sensorimotor and Cognitive Factors Associated With Gait Variability: A Longitudinal Population-Based Study

Background: Greater gait variability increases the risk of falls. However, little is known about changes in gait variability in older age. The aims of this study were to examine: (1) change in gait variability across time and (2) factors that predict overall mean gait variability and its change over time. Methods: Participants (n = 410; mean age 72 years) were assessed at baseline and during follow up visits at an average of 30 and 54 months. Step time, step length, step width and double support time (DST) were measured using a GAITRite walkway. Variability was calculated as the standard deviation of all steps for each individual. Covariates included demographic, medical, sensorimotor and cognitive factors. Mixed models were used to determine (1) change in gait variability over time (2) factors that predicted or modified any change. Results: Over 4.6 years the presence of cardiovascular disease at baseline increased the rate of change for step length variability (p = 0.04 for interaction), lower education increased the rate of change for DST variability (p = 0.04) and weaker quadriceps strength increased the rate of change for step width variability (p = 0.01). Greater postural sway predicted greater variability on average across the three phases (p < 0.05). Arthritis, a higher body mass index (BMI), slower processing speed and lower quadriceps strength predicted greater mean step time variability (p < 0.05). Arthritis and a higher BMI predicted greater mean step length variability, while slower processing speed and BMI predicted greater mean DST variability (p < 0.05). Conclusion: Over a nearly 5-year period, variability in different gait measures do not show uniform changes over time. Furthermore, each variability measure appears to be modified and predicted by different factors. These results provide information on potential targets for future trials to maintain mobility and independence in older age.

Get a grip: individual variations in grip strength are a marker of brain health

Demonstrations that grip strength has predictive power in relation to a range of health conditions-even when these are assessed decades later-has motivated claims that hand-grip dynamometry has the potential to serve as a "vital sign" for middle-aged and older adults. Central to this belief has been the assumption that grip strength is a simple measure of physical performance that provides a marker of muscle status in general, and sarcopenia in particular. It is now evident that while differences in grip strength between individuals are influenced by musculoskeletal factors, "lifespan" changes in grip strength within individuals are exquisitely sensitive to integrity of neural systems that mediate the control of coordinated movement. The close and pervasive relationships between age-related declines in maximum grip strength and expressions of cognitive dysfunction can therefore be understood in terms of the convergent functional and structural mediation of cognitive and motor processes by the human brain. In the context of aging, maximum grip strength is a discriminating measure of neurological function and brain health.

Sensor-based balance training with motion feedback in people with mild cognitive impairment

Some individuals with mild cognitive impairment (MCI) experience not only cognitive deficits but also a decline in motor function, including postural balance. This pilot study sought to estimate the feasibility, user experience, and effects of a novel sensor-based balance training program. Patients with amnestic MCI (mean age 78.2 yr) were randomized to an intervention group (IG, n = 12) or control group (CG, n = 10). The IG underwent balance training (4 wk, twice a week) that included weight shifting and virtual obstacle crossing. Real-time visual/audio lower-limb motion feedback was provided from wearable sensors. The CG received no training. User experience was measured by a questionnaire. Postintervention effects on balance (center of mass sway during standing with eyes open [EO] and eyes closed), gait (speed, variability), cognition, and fear of falling were measured. Eleven participants (92%) completed the training and expressed fun, safety, and helpfulness of sensor feedback. Sway (EO, p = 0.04) and fear of falling (p = 0.02) were reduced in the IG compared to the CG. Changes in other measures were nonsignificant. Results suggest that the sensor-based training paradigm is well accepted in the target population and beneficial for improving postural control. Future studies should evaluate the added value of the sensor-based training compared to traditional training.

Body position and motor imagery strategy effects on imagining gait in healthy adults: Results from a cross-sectional study

Background

Assessment of changes in higher levels of gait control with aging is important to better understand age-related gait instability, with the perspective to improve the screening of individuals at risk for falls. The comparison between actual Timed Up and Go test (aTUG) and its imagined version (iTUG) is a simple clinical way to assess age-related changes in gait control. The modulations of iTUG performances by body positions and motor imagery (MI) strategies with normal aging have not been evaluated yet. This study aims 1) to compare the aTUG time with the iTUG time under different body positions (i.e., sitting, standing or supine) in healthy young and middle age, and older adults, and 2) to examine the associations of body positions and MI strategies (i.e., egocentric versus allocentric) with the time needed to complete the iTUG and the delta TUG time (i.e., relative difference between aTUG and iTUG) while taking into consideration clinical characteristics of participants.

Methods

A total of 60 healthy individuals (30 young and middle age participants 26.6±7.4 years, and 30 old participants 75.0±4.4 years) were recruited in this cross-sectional study. The iTUG was performed while sitting, standing and in supine position. Times of the aTUG, the iTUG under the three body positions, the TUG delta time and the strategies of MI (i.e., ego representation, defined as representation of the location of objects in space relative to the body axes of the self, versus allocentric representation defined as encoding information about body movement with respect to other object, the location of body being defined relative to the location of other objects) were used as outcomes. Age, sex, height, weight, number of drugs taken daily, level of physical activity and prevalence of closed eyes while performing iTUG were recorded.

Results

The aTUG time is significantly greater than iTUG while sitting and standing (P<0.001), except when older participants are standing. A significant difference is reported between iTUG while sitting or standing and iTUG while supine (P≤0.002), higher time being reported in supine position. The multiple linear regressions confirm that the supine position is associated with significant increased iTUG (P≤0.04) and decreased TUG delta time (P≤0.010), regardless of the adjustment. Older participants use the allocentric MI while imagining TUG more frequently than young and middle age participants, regardless of body positions (P≤0.001). Allocentric MI strategy is associated with a significant decrease in iTUG (P = 0.037) only while adjusting for age. A significant increase of iTUG time is associated with age (P≤0.026).

Conclusions

Supine position while imagining TUG represents a more accurate position of actual performance of TUG. Age has a limited effect on iTUG performance but is associated with a change in MI from ego to allocentric representation that decreases the iTUG performances, and thus increases the discrepancy with aTUG.

Comparison of Gait Parameters for Predicting Cognitive Decline: The Mayo Clinic Study of Aging

BACKGROUND

Previous studies reported that slower gait speed might predict cognitive impairment and dementing illnesses, supporting the role of gait speed as a possible subclinical marker of cognitive impairment. However, the predictive value of other gait parameters for cognitive decline is unclear.

OBJECTIVE

To investigate and compare the association with, and prediction of, specific gait parameters for cognition in a population-based sample.

METHODS

The analysis included 3,426 cognitively normal participants enrolled in the Mayo Clinic Study of Aging. At baseline and every 15 months (mean follow-up = 1.93 years), participants had a study coordinator evaluation, neurological examination, and a neuropsychological assessment using nine tests that covered four domains. Gait parameters were assessed with the GAITRite® instrument. General linear mixed effects models were used to compute the annualized rate of change in cognitive domain z-scores, controlling for age, sex, education, depression, comorbidities, body mass index, APOE ɛ4 allele, and visit number, and excluding individuals with a history of stroke, alcoholism, Parkinson's disease, subdural hematoma, and normal pressure hydrocephalus.

RESULTS

Spatial (stride length), temporal (ambulatory time, gait speed, step count, cadence, double support time), and spatiotemporal (cadence) gait parameters, and greater intraindividual variability in stride length, swing time, and stance time were associated with a significant decline in global cognition and in specific domains including memory, executive function, visuospatial, and language.

CONCLUSIONS

Spatial, temporal, and spatiotemporal measures of gait and greater variability of gait parameters were associated with and predictive of both global- and domain-specific cognitive decline.

Subjective Memory Impairment and Gait Variability in Cognitively Healthy Individuals: Results from a Cross-Sectional Pilot Study

BACKGROUND

Increased stride time variability has been associated with memory impairment in mild cognitive impairment. Subjective memory impairment (SMI) is considered the earliest clinical stage of Alzheimer's disease (AD). The association between increased stride time variability and SMI has not been reported.

OBJECTIVE

This study aims to examine the association of stride time variability while performing single and dual tasking with SMI in cognitively healthy individuals (CHI).

METHODS

A total of 126 CHI (15 without SMI, 69 with SMI expressed by participants, 10 with SMI expressed by participant's relative, and 32 with SMI expressed by both participants and their relatives) were included in this cross-sectional study. The coefficient of variation (CoV) of stride time and walking speed were recorded under usual condition and while counting backwards. Age, gender, body mass index, number of drugs taken daily, use of psychoactive drugs, fear of falling, history of previous falls, and walking speed were used as covariates.

RESULTS

The multiple linear regression models showed that greater CoV of stride time while counting backwards, but not while single tasking, was associated with a participant's relative SMI (p = 0.038).

CONCLUSION

This study found a specific association between SMI expressed by a participant's relative and a greater CoV of stride time (i.e., worse performance) while dual tasking, suggesting that the association between gait variability and memory may be present in the earliest stages of memory impairment. Thus, gait variability under dual-task in individuals with SMI expressed by their relatives can be a potential biomarker of AD.

Association of increased gait variability while dual tasking and cognitive decline: results from a prospective longitudinal cohort pilot study

Dual task-related changes in gait are considered as a sensitive and a specific marker of adverse effects of cognitive impairment on the highest levels of gait control. No study has examined the longitudinal association between gait performance while dual tasking and the occurrence of cognitive decline. This study aims to examine the association of stride time parameters (i.e., mean value and coefficient of variation (CoV)) during single and dual tasking with the occurrence of cognitive decline in non-demented older community dwellers. A total of 56 non-demented community dwellers were recruited in a longitudinal prospective cohort study. Mini-Mental Status Examination (MMSE) scores at baseline assessment and at 5-year follow-up assessment, and mean value and CoV of stride time at self-selected usual pace, while usual walking and dual tasking (i.e., counting backward and verbal fluency task) at baseline assessment were recorded. Variation (i.e., delta) of MMSE score from baseline to follow-up assessment as well as of stride time parameters from single to dual task was used as outcomes. Worse stride time values were reported while dual tasking compared to single tasking (P < 0.03). An increase of mean value, CoV, and delta of CoV of stride time was associated with an increased delta MMSE while performing verbal fluency task (P < 0.05). Worsening stride time parameters while performing a verbal fluency task at baseline assessment was associated with decline in MMSE score during the 5-year follow-up period in this sample of older community dwellers.

Gait characteristics and their discriminative power in geriatric patients with and without cognitive impairment

BACKGROUND

A detailed gait analysis (e.g., measures related to speed, self-affinity, stability, and variability) can help to unravel the underlying causes of gait dysfunction, and identify cognitive impairment. However, because geriatric patients present with multiple conditions that also affect gait, results from healthy old adults cannot easily be extrapolated to geriatric patients. Hence, we (1) quantified gait outcomes based on dynamical systems theory, and (2) determined their discriminative power in three groups: healthy old adults, geriatric patients with- and geriatric patients without cognitive impairment.

METHODS

For the present cross-sectional study, 25 healthy old adults recruited from community (65 ± 5.5 years), and 70 geriatric patients with (n = 39) and without (n = 31) cognitive impairment from the geriatric dayclinic of the MC Slotervaart hospital in Amsterdam (80 ± 6.6 years) were included. Participants walked for 3 min during single- and dual-tasking at self-selected speed while 3D trunk accelerations were registered with an IPod touch G4. We quantified 23 gait outcomes that reflect multiple gait aspects. A multivariate model was built using Partial Least Square- Discriminant Analysis (PLS-DA) that best modelled participant group from gait outcomes.

RESULTS

For single-task walking, the PLS-DA model consisted of 4 Latent Variables that explained 63 and 41% of the variance in gait outcomes and group, respectively. Outcomes related to speed, regularity, predictability, and stability of trunk accelerations revealed with the highest discriminative power (VIP > 1). A high proportion of healthy old adults (96 and 93% for single- and dual-task, respectively) was correctly classified based on the gait outcomes. The discrimination of geriatric patients with and without cognitive impairment was poor, with 57% (single-task) and 64% (dual-task) of the patients misclassified.

CONCLUSIONS

While geriatric patients vs. healthy old adults walked slower, and less regular, predictable, and stable, we found no differences in gait between geriatric patients with and without cognitive impairment. The effects of multiple comorbidities on geriatric patients' gait possibly causes a 'floor-effect', with no room for further deterioration when patients develop cognitive impairment. An accurate identification of cognitive status thus necessitates a multifactorial approach.

Association between mild cognitive impairment and trajectory-based spatial parameters during timed up and go test using a laser range sensor

Background

The Timed Up and Go (TUG) test may be a useful tool to detect not only mobility impairment but also possible cognitive impairment. In this cross-sectional study, we used the TUG test to investigate the associations between trajectory-based spatial parameters measured by laser range sensor (LRS) and cognitive impairment in community-dwelling older adults.

Methods

The participants were 63 community-dwelling older adults (mean age, 73.0 ± 6.3 years). The trajectory-based spatial parameters during the TUG test were measured using an LRS. In each forward and backward phase, we calculated the minimum distance from the marker, the maximum distance from the x-axis (center line), the length of the trajectories, and the area of region surrounded by the trajectory of the center of gravity and the x-axis (center line). We measured mild cognitive impairment using the Mini-Mental State Examination score (26/27 was the cut-off score for defining mild cognitive impairment).

Results

Compared with participants with normal cognitive function, those with mild cognitive impairment exhibited the following trajectory-based spatial parameters: short minimum distance from the marker (p = 0.044), narrow area of center of gravity in the forward phase (p = 0.012), and a large forward/whole phase ratio of the area of the center of gravity (p = 0.026) during the TUG test. In multivariate logistic regression analyses, a short minimum distance from the marker (odds ratio [OR]: 0.82, 95% confidence interval [CI]: 0.69–0.98), narrow area of the center of gravity in the forward phase (OR: 0.01, 95% CI: 0.00–0.36), and large forward/whole phase ratio of the area of the center of gravity (OR: 0.94, 95% CI: 0.88–0.99) were independently associated with mild cognitive impairment.

Conclusions

In conclusion, our results indicate that some of the trajectory-based spatial parameters measured by LRS during the TUG test were independently associated with cognitive impairment in older adults. In particular, older adults with cognitive impairment exhibit shorter minimum distances from the marker and asymmetrical trajectories during the TUG test.

Guidelines for Assessment of Gait and Reference Values for Spatiotemporal Gait Parameters in Older Adults: The Biomathics and Canadian Gait Consortiums Initiative

Background: Gait disorders, a highly prevalent condition in older adults, are associated with several adverse health consequences. Gait analysis allows qualitative and quantitative assessments of gait that improves the understanding of mechanisms of gait disorders and the choice of interventions. This manuscript aims (1) to give consensus guidance for clinical and spatiotemporal gait analysis based on the recorded footfalls in older adults aged 65 years and over, and (2) to provide reference values for spatiotemporal gait parameters based on the recorded footfalls in healthy older adults free of cognitive impairment and multi-morbidities. Methods: International experts working in a network of two different consortiums (i.e., Biomathics and Canadian Gait Consortium) participated in this initiative. First, they identified items of standardized information following the usual procedure of formulation of consensus findings. Second, they merged databases including spatiotemporal gait assessments with GAITRite® system and clinical information from the "Gait, cOgnitiOn & Decline" (GOOD) initiative and the Generation 100 (Gen 100) study. Only healthy-free of cognitive impairment and multi-morbidities (i.e., ≤ 3 therapeutics taken daily)-participants aged 65 and older were selected. Age, sex, body mass index, mean values, and coefficients of variation (CoV) of gait parameters were used for the analyses. Results: Standardized systematic assessment of three categories of items, which were demographics and clinical information, and gait characteristics (clinical and spatiotemporal gait analysis based on the recorded footfalls), were selected for the proposed guidelines. Two complementary sets of items were distinguished: a minimal data set and a full data set. In addition, a total of 954 participants (mean age 72.8 ± 4.8 years, 45.8% women) were recruited to establish the reference values. Performance of spatiotemporal gait parameters based on the recorded footfalls declined with increasing age (mean values and CoV) and demonstrated sex differences (mean values). Conclusions: Based on an international multicenter collaboration, we propose consensus guidelines for gait assessment and spatiotemporal gait analysis based on the recorded footfalls, and reference values for healthy older adults.

Loss of gait control assessed by cognitive-motor dual-tasks: pros and cons in detecting people at risk of developing Alzheimer's and Parkinson's diseases

Alzheimer's and Parkinson's diseases are age-related progressive neurodegenerative diseases of increasing prevalence worldwide. In the absence of curative therapy, current research is interested in prevention, by identifying subtle signs of early-stage neurodegeneration. Today, the field of behavioral neuroscience has emerged as one of the most promising areas of research on this topic. Recently, it has been shown that the exacerbation of gait disorders under dual-task conditions (i.e., simultaneous performance of cognitive and motor tasks) could be a characteristic feature of Alzheimer's and Parkinson's diseases. The cognitive-motor dual-task paradigm during walking allows to assess whether (i) executive attention is abnormally impaired in prodromal Alzheimer's disease or (ii) compensation strategies are used in order to preserve gait function when the basal ganglia system is altered in prodromal Parkinson's disease. This review aims at (i) identifying patterns of dual-task-related gait changes that are specific to Alzheimer's and Parkinson's diseases, respectively, (ii) demonstrating that these changes could potentially be used as prediagnostic markers for disease onset, (iii) reviewing pros and cons of existing dual-task studies, and (iv) proposing future directions for clinical research.

Improving Dual-Task Walking Paradigms to Detect Prodromal Parkinson's and Alzheimer's Diseases

Gait control is a complex movement, relying on spinal, subcortical, and cortical structures. The presence of deficits in one or more of these structures will result in changes in gait automaticity and control, as is the case in several neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD). By reviewing recent findings in this field of research, current studies have shown that gait performance assessment under dual-task conditions could contribute to predict both of these diseases. Such suggestions are relevant mainly for people at putatively high risk of developing AD (i.e., older adults with mild cognitive impairment subtypes) or PD (i.e., older adults with either Mild Parkinsonian signs or LRRK2 G2019S mutation). Despite the major importance of these results, the type of cognitive task that should be used as a concurrent secondary task has to be selected among the plurality of tasks proposed in the literature. Furthermore, the key aspects of gait control that represent sensitive and specific "gait signatures" for prodromal AD or PD need to be determined. In the present perspective article, we suggest the use of a Stroop interference task requiring inhibitory attentional control and a set-shifting task requiring reactive flexibility as being particularly relevant secondary tasks for challenging gait in prodromal AD and PD, respectively. Investigating how inhibition and cognitive flexibility interfere with gait control is a promising avenue for future research aimed at enhancing early detection of AD and PD, respectively.

What can gait tell us about dementia? Review of epidemiological and neuropsychological evidence

BACKGROUND

Cognitive impairment and gait disorders in people over the age of 65 represent major public health issues because of their high frequency, their link to poor outcomes and high costs. Research has demonstrated that these two geriatric syndromes are closely related.

METHODS AND RESULTS

We aim to review the evidence supporting the relationship between gait and cognitive impairment, particularly focusing on epidemiological and neuropsychological studies in patients with Mild cognitive impairment, Alzheimer's disease and Vascular dementia. The review demonstrates that gait and cognition are closely related, but our knowledge of their interrelationship is limited. Emerging evidence shows that gait analysis has the potential to contribute to diagnosis and prognosis of cognitive impairment.

CONCLUSIONS

An integrated approach for evaluating these major geriatric syndromes, based on their close relationship, will not only increase our understanding of cognitive-motor interactions, but most importantly may be used to aid early diagnosis, prognosis and the development of new interventions.

Gait disorders in the elderly and dual task gait analysis: a new approach for identifying motor phenotypes

BACKGROUND

Gait disorders and gait analysis under single and dual-task conditions are topics of great interest, but very few studies have looked for the relevance of gait analysis under dual-task conditions in elderly people on the basis of a clinical approach.

METHODS

An observational study including 103 patients (mean age 76.3 ± 7.2, women 56%) suffering from gait disorders or memory impairment was conducted. Gait analysis under dual-task conditions was carried out for all patients. Brain MRI was performed in the absence of contra-indications. Three main gait variables were measured: walking speed, stride frequency, and stride regularity. For each gait variable, the dual task cost was computed and a quartile analysis was obtained. Nonparametric tests were used for all the comparisons (Wilcoxon, Kruskal-Wallis, Fisher or Chi2 tests).

RESULTS

Four clinical subgroups were identified: gait instability (45%), recurrent falls (29%), memory impairment (18%), and cautious gait (8%). The biomechanical severity of these subgroups was ordered according to walking speed and stride regularity under both conditions, from least to most serious as follows: memory impairment, gait instability, recurrent falls, cautious gait (p < 0.01 for walking speed, p = 0.05 for stride regularity). According to the established diagnoses of gait disorders, 5 main pathological subgroups were identified (musculoskeletal diseases (n = 11), vestibular diseases (n = 6), mild cognitive impairment (n = 24), central nervous system pathologies, (n = 51), and without diagnosis (n = 8)). The dual task cost for walking speed, stride frequency and stride regularity were different among these subgroups (p < 0.01). The subgroups mild cognitive impairment and central nervous system pathologies both showed together a higher dual task cost for each variable compared to the other subgroups combined (p = 0.01). The quartile analysis of dual task cost for stride frequency and stride regularity allowed the identification of 3 motor phenotypes (p < 0.01), without any difference for white matter hyperintensities, but with an increased Scheltens score from the first to the third motor phenotype (p = 0.05).

CONCLUSIONS

Gait analysis under dual-task conditions in elderly people suffering from gait disorders or memory impairment is of great value in assessing the severity of gait disorders, differentiating between peripheral pathologies and central nervous system pathologies, and identifying motor phenotypes. Correlations between motor phenotypes and brain imaging require further studies.

Apathy and higher level of gait control in normal pressure hydrocephalus

Apathy represents the most common behavioral disturbance in patients with suspicion of idiopathic normal pressure hydrocephalus (iNPH) and has a major impact on quality of life. However, its impact on gait -the hallmark motor disturbance of iNPH - has never been studied yet. This study aims to evaluate the impact of apathy on higher level of gait control in patients with suspicion of iNPH. Stride time variability (STV), a marker of higher level of gait control, was quantified during usual walking (single task) and during walking while performing simultaneously cognitive tasks (dual task) of counting and verbal fluency. Among 46 patients with suspicion of iNPH (77.6±6.7years; 34.8% women), 30 (65.2%) presented apathy (defined by a score≥14 on the Starkstein apathy scale). Backward counting induced more important worsening of STV (i.e. increasing STV) in apathetic compared to non-apathetic patients (14.8±25.1% versus 9.0±20.4%; p=0.005), while both groups presented similar executive functioning. These findings suggest that apathy contributes to gait disorders in iNPH. Apathy is easy to monitor and should be considered as a target symptom of treatment.

Correlation between functional mobility and cognitive performance in older adults with cognitive impairment

Association between cognitive impairment and gait performance occurs in mild cognitive impairment (MCI) and Alzheimer's disease (AD), particularly under "divided attention" conditions, leading to a greater risk of falls. We studied 36 controls, 42 MCI, and 26 mild AD patients, using the Timed Up-and-Go test (TUG) under four conditions: TUG single - TUG1; TUG cognitive - TUG2; TUG manual -TUG3; TUG cognitive and manual - TUG4. Cognition was assessed using the MMSE, SKT, Exit25, and TMT (A and B). We found significant correlations between cognitive scores and TUG2 [r values (MMSE: -0.383, TMT-A: 0.430, TMT-B: 0.386, Exit25: 0.455, SKT: 0.563)] and TUG4 [(MMSE: -0.398, TMT-A: 0.384, TMT-B: 0.352,Exit25: 0.466, SKT: 0.525)] in the AD group, and between all TUG modalities and SKT in MCI and AD. Our results revealed that functional mobility impairment in cognitive dual tasks correlated to cognitive decline in AD patients and to attention and memory impairment in MCI.

Apolipoprotein E Genotype Linked to Spatial Gait Characteristics: Predictors of Cognitive Dual Task Gait Change

Background

Developing measures to detect preclinical Alzheimer’s Disease is vital, as prodromal stage interventions may prove more efficacious in altering the disease’s trajectory. Gait changes may serve as a useful clinical heuristic that precedes cognitive decline. This study provides the first systematic investigation of gait characteristics relationship with relevant demographic, physical, genetic (Apolipoprotein E genotype), and health risk factors in non-demented older adults during a cognitive-load dual task walking condition.

Methods

The GAITRite system provided objective measurement of gait characteristics in APOE-e4 “carriers” (n = 75) and “non-carriers” (n = 224). Analyses examined stride length and step time gait characteristics during simple and dual-task (spelling five-letter words backwards) conditions in relation to demographic, physical, genetic, and health risk factors.

Results

Slower step time and shorter stride length associated with older age, greater health risk, and worse physical performance (ps < .05). Men and women differed in height, gait characteristics, health risk factors and global cognition (ps < .05). APOE-e4 associated with a higher likelihood of hypercholesterolemia and overall illness index scores (ps < .05). No genotype-sex interactions on gait were found. APOE-e4 was linked to shorter stride length and greater dual-task related disturbances in stride length.

Conclusions

Stride length has been linked to heightened fall risk, attention decrements and structural brain changes in older adults. Our results indicate that stride length is a useful behavioral marker of cognitive change that is associated with genetic risk for AD. Sex disparities in motor decline may be a function of health risk factors.