Executive function, memory, and gait speed decline in well-functioning older adults

Long-Term Running Exercise Delays Age-Related Changes in White Matter in Rats

Running exercise, one of the strategies to protect brain function, has positive effects on neurons and synapses in the cortex and hippocampus. However, white matter, as an important structure of the brain, is often overlooked, and the effects of long-term running exercise on white matter are unknown. Here, 14-month-old male Sprague–Dawley (SD) rats were divided into a middle-aged control group (18-month-old control group), an old control group (28-month-old control group), and a long-term runner group (28-month-old runner group). The rats in the runner group underwent a 14-month running exercise regime. Spatial learning ability was tested using the Morris water maze, and white matter volume, myelinated fiber parameters, total mature oligodendrocyte number, and white matter capillary parameters were investigated using stereological methods. The levels of growth factors related to nerve growth and vascular growth in peripheral blood and the level of neurite outgrowth inhibitor-A (Nogo-A) in white matter were measured using an enzyme-linked immunosorbent assay (ELISA). The present results indicated that long-term running exercise effectively delayed the age-related decline in spatial learning ability and the atrophy of white matter by protecting against age-related changes in myelinated fibers and oligodendrocytes in the white matter. Moreover, long-term running exercise prevented age-related changes in capillaries within white matter, which might be related to the protective effects of long-term exercise on aged white matter.

Are Cognitive Subtypes Associated with Dual-Task Gait Performance in a Clinical Setting?

BACKGROUND

Poor dual-task gait (walking while performing a cognitively demanding task) has been linked to progression to dementia in older adults with mild cognitive impairment (MCI). However, many of these findings come from research environments; gait performance across the cognitive spectrum has not previously been studied in a clinical setting.

OBJECTIVE

To examine whether patients from a memory clinic show differences in usual and dual-task gait speed and dual-task cost (DTC) based on cognitive diagnosis.

METHODS

Patients in the Aging Brain and Memory Clinic (London, ON) performed a usual gait walk and three dual-task gait walks: counting backwards by ones, naming animals, and counting backwards by seven (serial sevens) out loud. Patients were timed with a stopwatch over a six-meter path marked on the floor. One-way ANOVA was performed to evaluate associations between gait speed and DTC (%) across groups.

RESULTS

One hundred ninety-four patients with subjective cognitive impairment (SCI; n = 46), MCI (n = 77), or dementia (n = 71) were assessed. Performance in usual (p < 0.001) and dual-task gait speed (counting gait p < 0.001; naming animals p < 0.001; serial sevens p = 0.004) decreased across the spectrum of cognitive impairment. Patients with dementia had significantly higher DTC in both counting gait (p = 0.02) and naming animals (p = 0.04) conditions compared with patients with SCI and MCI, who had statistically similar DTC in all conditions.

CONCLUSION

Dual-task gait performance significantly declines across the cognitive spectrum in a clinical setting. Dual-task gait testing may be used in conjunction with traditional assessments for diagnosing cognitive impairments.

Association Between Physical Performance and Cognitive Function in Older Adults Across Multiple Studies: A Pooled Analysis Study

Background and Objectives

While several studies have examined the association between cognitive and physical function, the consistency of these associations across functional contexts is unclear. The consistency of the association between cognitive and physical function performance was examined at baseline across 17 clinical studies with diverse and heterogeneous conditions such as overweight/obese, sedentary, at risk for a mobility disability, osteoarthritis, low vitamin D, or had signs of cognitive impairment.

Research Design and Methods

Data are from 1,388 adults 50 years and older who completed a cognitive and physical function assessment as part of a research study at the Wake Forest Alzheimer's Disease Research Center or the Wake Forest Older Americans Independence Center. Linear regression models were used to relate cognitive measures (Mini-Mental Status Examination, Montreal Cognitive Assessment, and the Digit Symbol Substitution Task) and physical measures (the Short Physical Performance Battery and hand grip strength) for the whole sample and treat each study as a fixed effect. All models controlled for age, sex, race, and body mass index.

Results

Overall, there was a significant association between higher scores on the Mini-Mental Status Examination (per standard deviation) and better physical function performance (Short Physical Performance Battery score b = 0.24, p < .001) and its components (gait speed, chair rise, and standing balance; ps < .05). Higher scores on the Montreal Cognitive Assessment produced similar results (Short Physical Performance Battery score b = 0.31, p ≤ .001), and higher scores on the Digit Symbol Substitution Task were also significantly associated with a better Short Physical Performance Battery score (b = 0.75, p < .001). The relationship between Digit Symbol Substitution Task and physical function performance demonstrated a stronger magnitude of association compared to the Mini-Mental Status Examination or Montreal Cognitive Assessment.

Discussion and Implications

Older adults with heterogeneous health conditions showed a consistent pattern between better cognitive function and better physical function performance with the strongest association among Digit Symbol Substitution Task scores.

The Association between Health Literacy and Gait Speed in Community-Dwelling Older Adults

The association between gait speed, a vital health outcome in older adults, and health literacy, an important health promotion aspect, is unclear. This study examined the relationship of gait speed with health literacy, physical function, and cognitive function in community-dwelling older adults. The subjects were 240 older adults (52 men, mean age 73.8 ± 6.0 years). Gender, age, and education were self-reported, while height and weight were measured directly. Health literacy was evaluated using Communicative and Critical Health Literacy (CCHL). Grip strength, knee extension strength, toe-grip strength, sit-up test, sit-and-reach test, one-leg stance test time, 30-s chair-stand test (CS-30), and normal gait speed were measured. Subjects were divided into two groups based on normal gait speed—fast (speed ≥ 1.3 m/s) and slow (<1.3 m/s). In the logistic regression analysis, the dependent variable was normal gait speed (fast/slow). Four logistic regression models were utilized to determine whether health literacy affects gait speed. Height and CCHL were found to independently affect gait speed. That health literacy influences gait speed is a new discovery.

Preserving Mobility in Older Adults with Physical Frailty and Sarcopenia: Opportunities, Challenges, and Recommendations for Physical Activity Interventions

One of the most widely conserved hallmarks of aging is a decline in functional capabilities. Mobility loss is particularly burdensome due to its association with negative health outcomes, loss of independence and disability, and the heavy impact on quality of life. Recently, a new condition, physical frailty and sarcopenia, has been proposed to define a critical stage in the disabling cascade. Physical frailty and sarcopenia are characterized by weakness, slowness, and reduced muscle mass, yet with preserved ability to move independently. One of the strategies that have shown some benefits in combatting mobility loss and its consequences for older adults is physical activity. Here, we describe the opportunities and challenges for the development of physical activity interventions in people with physical frailty and sarcopenia. The aim of this article is to review age-related physio(patho)logical changes that impact mobility in old age and to provide recommendations and procedures in accordance with the available literature.

Sensorimotor Inhibition and Mobility in Genetic Subgroups of Parkinson's Disease

Background: Mobility and sensorimotor inhibition impairments are heterogeneous in Parkinson's disease (PD). Genetics may contribute to this heterogeneity since the apolipoprotein (APOE) ε4 allele and glucocerebrosidase (GBA) gene variants have been related to mobility impairments in otherwise healthy older adult (OA) and PD cohorts. The purpose of this study is to determine if APOE or GBA genetic status affects sensorimotor inhibition and whether the relationship between sensorimotor inhibition and mobility differs in genetic sub-groups of PD. Methods: Ninety-three participants with idiopathic PD (53 non-carriers; 23 ε4 carriers; 17 GBA variants) and 72 OA (45 non-carriers; 27 ε4 carriers) had sensorimotor inhibition characterized by short-latency afferent inhibition. Mobility was assessed in four gait domains (pace/turning, rhythm, trunk, variability) and two postural sway domains (area/jerkiness and velocity) using inertial sensors. Results: Sensorimotor inhibition was worse in the PD than OA group, with no effect of genetic status. Gait pace/turning was slower and variability was higher (p < 0.01) in PD compared to OA. Postural sway area/jerkiness (p < 0.01) and velocity (p < 0.01) were also worse in the PD than OA group. Genetic status was not significantly related to any gait or postural sway domain. Sensorimotor inhibition was significantly correlated with gait variability (r = 0.27; p = 0.02) and trunk movement (r = 0.23; p = 0.045) in the PD group. In PD non-carriers, sensorimotor inhibition related to variability (r = 0.35; p = 0.010) and trunk movement (r = 0.31; p = 0.025). In the PD ε4 group, sensorimotor inhibition only related to rhythm (r = 0.47; p = 0.024), while sensorimotor inhibition related to pace/turning (r = -0.49; p = 0.046) and rhythm (r = 0.59; p = 0.013) in the PD GBA group. Sensorimotor inhibition was significantly correlated with gait pace/turning (r = -0.27; p = 0.04) in the OA group. There was no relationship between sensorimotor inhibition and postural sway. Conclusion: ε4 and GBA genetic status did not affect sensorimotor inhibition or mobility impairments in this PD cohort. However, worse sensorimotor inhibition was associated with gait variability in PD non-carriers, but with gait rhythm in PD ε4 carriers and with gait rhythm and pace in PD with GBA variants. Impaired sensorimotor inhibition had a larger effect on mobility in people with PD than OA and affected different domains of mobility depending on genetic status.

Joint trajectories of cognition and gait speed in Mexican American and European American older adults: The San Antonio longitudinal study of aging

OBJECTIVES

Cognitive decline and gait speed slowing are independent predictors of disability and mortality. While both factors increase in prevalence with advancing age, little is known about their combined patterns of change. The study goal was to identify joint trajectories of cognition and gait speed within an aging bi-ethnic cohort of Mexican Americans and European Americans.

METHODS/DESIGN

Participants included 182 Mexican Americans and 188 European Americans, ages 65 to 74, who were followed over a mean of 9.5 years. Cognition was assessed with the mini-mental state examination and gait speed was examined with a timed 10-ft walk. Joint trajectory classes of cognition and gait speed were identified with latent growth mixture modeling. Odd-ratios assessed predictors for trajectory classes.

RESULTS

Three latent trajectory classes were identified: (a) relatively stable cognition and gait (termed stable cognition and gait class, 65.4%); (b) deteriorating cognition and gait (termed cognitive and physical vulnerability class, 22.2%); (c) stable cognition and deteriorating gait (termed physical vulnerability class, 12.4%). The odds of classification in the cognitive and physical vulnerability class vs stable cognition and gait class was associated with Mexican American ethnicity (OR = 3.771, P = .016), age (OR = 1.186, P = .017), income (OR = 0.828, P = .029), education (OR = 0.703, P < .001), and diabetes (OR = 4.547, P = .010). The odds of classification in the physical vulnerability class was associated with female sex (OR = 6.481, P = .004) and body mass index (OR = 1.118, P = .025).

CONCLUSIONS

The trajectories of cognition and gait speed were generally parallel, suggesting the two domains may act synergistically to shape important health outcomes. Socioeconomic disparities and Mexican American ethnicity independently conferred risk for accelerated decline.

An Investigation of the Predictors of Comfortable and Fast Gait Speed in Community-Dwelling Older Adults

BACKGROUND/PURPOSE

To identify the unique predictors of comfortable and fast gait speed in community-dwelling older adults using measures of physical performance (eg, lower extremity strength and balance), self-reported balance confidence, and global cognitive function.

METHODS

Demographic information was collected from 60 healthy, community-dwelling older adults older than 60 years. Participants completed the following assessments: Mini-Mental State Examination; Activities-Specific Balance Confidence Scale; 30-second Chair Stand (30-SCS); Functional Reach (FR); and gait speed (comfortable and fast) using the GAITRite system. Hierarchical linear regression was used to examine the relationship of both fast and comfortable gait speeds with functional performance (CST and FR), cognition (Mini-Mental State Examination), Activities-Specific Balance Confidence Scale, and demographic information (age, gender, and body mass index).

RESULTS AND DISCUSSION

Functional performance measures (30-SCS and FR) explained 55.4% and 64.7%, respectively, of the variance in comfortable and fast gait speed. Unique predictors for comfortable gait speed included 30-SCS, FR, and body mass index. Unique predictors of fast gait speed included 30-SCS, FR, gender, body mass index, and Activities-Specific Balance Confidence Scale score. These predictors explained 68.5% and 80.4% of the total variance in comfortable and fast gait speed, respectively. Global cognition was not a unique predictor of gait speed when performance measures were statistically controlled. However, the current study measured global cognitive status rather than the specific cognitive constructs, such as processing speed or executive function. Further research is needed to determine the role of cognition in the composition of gait speed.

CONCLUSIONS

Gait speed is an important indicator for many outcomes such as fall risk, mortality, and functional status. Understanding that key variables of strength and balance comprise a large portion of gait speed allows clinicians to better direct their care and optimize rehabilitation outcomes. This study specifically used functional measures of strength and balance that can be easily implemented in the clinical setting.

Hearing Loss and Physical Functioning Among Adults with Heart Failure: Data from NHANES

Background

Hearing loss (HL) is associated with poor physical functioning among older adults, yet this association has not been examined in heart failure (HF), a disease in which both hearing loss and poor physical functioning are highly prevalent. We investigated whether this association exists in HF since HL represents a potentially modifiable risk factor for poor physical functioning.

Methods

We studied adults aged ≥70 years with self-reported HF in the National Health and Nutrition Examination Survey (NHANES). HL was assessed and categorized using pure-tone averages. Activities of daily living (ADLs), instrumental ADLs (IADLs), leisure and social activities (LSA), lower extremity mobility (LEM), and general physical activity (GPA) were assessed. Negative binomial regression was used to examine the association between HL and physical functioning

Results

One hundred eighty-one participants comprised our population. Those with ≥ moderate HL had more difficulty with ADLs (37.0% vs 24.0%, p=0.02), IADLs (36.0% vs 23.0%, p=0.05), and LEM (37.3% vs 20.0%, p=0.009), compared to participants with none or mild HL. In multivariable models, ≥ moderate HL was significantly associated with difficulty in physical functioning across four of the five domains: ADLs: PR: 1.71 (95% CI: 1.07-2.72); IADLs: PR: 1.71 (1.24-2.34); LEM: PR: 1.51 (1.01-2.26); and GPA: PR: 1.19 (1.00-1.41).

Conclusion

Among older adults with HF, moderate or greater HL was associated with a higher prevalence of difficulty with ADLs, IADLs, and LEM, compared to mild or no HL.

Executive function predicts decline in mobility after a fall: The MYHAT study

BACKGROUND

Evidence suggests that better cognitive functioning is associated with better mobility in older age. It is unknown whether older adults with better cognitive function are more resilient to mobility decline after a fall.

METHODS

Participants from the Monongahela Youghiogheny Healthy Aging Team (MYHAT) study were followed annually for up to 9 years for incident falls. We examined one-year (mean 1.0 year, SD 0.1) change in mobility pre- to post-fall using the Timed Up and Go (TUG) in relation to pre-fall cognition (executive function, attention, memory, and visuospatial function) among incident fallers (n = 598, mean age 79.1, SD = 7.0). Linear regression models tested the association of cognition with change in TUG. Interaction terms were tested to explore if age, sex, body mass index, physical activity, depressive symptoms, or visual acuity modified the associations of cognition and mobility among fallers. The association between cognition and one-year change in TUG was also tested in a comparison sample of non-fallers (n = 442, mean age 76.3, SD = 7.2).

RESULTS

Overall, mobility decline was greater in fallers compared to non-fallers. In fully-adjusted models, higher executive function, but not attention, memory, or visuospatial function, was associated with less decline in mobility among incident fallers. The effect was significantly stronger for those who were older, sedentary, and had lower body mass index. Higher scores in memory tests, but not in other domains, was associated with less mobility decline among non-fallers.

CONCLUSIONS

Higher executive function may offer resilience to mobility decline after a fall, especially among older adults with other risk factors for mobility decline. Future studies should assess whether executive function may be a helpful risk index of fall-related physical functional decline in geriatric settings.

Consensus on Shared Measures of Mobility and Cognition: From the Canadian Consortium on Neurodegeneration in Aging (CCNA)

Background

A new paradigm is emerging in which mobility and cognitive impairments, previously studied, diagnosed, and managed separately in older adults, are in fact regulated by shared brain resources. Deterioration in these shared brain mechanisms by normal aging and neurodegeneration increases the risk of developing dementia, falls, and fractures. This new paradigm requires an integrated approach to measuring both domains. We aim to identify a complementary battery of existing tests of mobility and cognition in community-dwelling older adults that enable assessment of motor-cognitive interactions.

Methods

Experts on mobility and cognition in aging participated in a semistructured consensus based on the Delphi process. After performing a scoping review to select candidate tests, multiple rounds of consultations provided structured feedback on tests that captured shared characteristics of mobility and cognition. These tests needed to be sensitive to changes in both mobility and cognition, applicable across research studies and clinics, sensitive to interventions, feasible to perform in older adults, been previously validated, and have minimal ceiling/floor effects.

Results

From 17 tests appraised, 10 tests fulfilled prespecified criteria and were selected as part of the “Core-battery” of tests. The expert panel also recommended a “Minimum-battery” of tests that included gait speed, dual-task gait speed, the Montreal Cognitive Assessment and Trail Making Test A&B.

Conclusions

A standardized assessment battery that captures shared characteristics of mobility and cognition seen in aging and neurodegeneration may increase comparability across research studies, detection of subtle or common reversible factors, and accelerate research progress in dementia, falls, and aging-related disabilities.

Global cognition predicts the incidence of poor physical performance among older adults: A cross-national study

AIM

The relationship between physical performance and cognition is well established. However, findings on the relationship between global cognition and the incidence of functional disability has been inconsistent. Using data from the International Mobility in Aging Study, we investigated the relationship between baseline cognitive function and the incidence of poor physical performance 2 years later.

METHODS

A total of 1071 community-dwelling participants (aged 64-75 years) from four sites in Canada and Latin America, with a Short Physical Performance Battery score ≥9 at baseline (good performance) were included. We carried out two sets of analyses, measuring cognition with either the Leganés Cognitive Test or the Montreal Cognitive Assessment. We used three logistic regression models, controlling for either no confounders, sociodemographic confounders or sociodemographic and health confounders. The full model was also stratified by site. A score <9 on the Short Physical Performance Battery indicated poor physical performance.

RESULTS

In the fully adjusted model, each 1-point increase in the baseline Leganés Cognitive Test score (range 0-32) was associated with a 10% decrease in the odds of incidence of poor physical performance at the 2-year follow-up (P = 0.019). Likewise, each 1-point increase in the baseline Montreal Cognitive Assessment score (range 0-30) was associated with a 16% decrease in the odds of developing poor physical performance (P = 0.005). When stratified by site, the results were significant at the Latin American sites (P = 0.02), but not at the Canadian sites (P = 0.08).

CONCLUSIONS

Poor baseline cognition is associated with the incidence of poor physical performance in community-dwelling older adults. To prevent physical disability, interventions addressing both cognitive and physical performance are required. Geriatr Gerontol Int 2020; ••: ••-••.

The association of a novel cognitive frailty index and physical functioning in older at-risk adults

Objectives: Cognitive frailty is a state at the lower end of the continuum of cognitive resilience in which one is at elevated risk for cognitive impairment and dementia. Metrics of a newly developed Cognitive Frailty Index (CFI) were examined for their association with objective functional limitations.Methods: We used baseline data from 607 participants from the Baltimore Experience Corps Trial with measures on the CFI, a computerized Stroop test, and Short Physical Performance Battery (SPPB) score ≤9. Multivariable log-binomial regression models were used to evaluate the associations of CFI metrics (mean reaction time (RT) for total, first-half and second-half trials per condition) with the SPPB. Latent growth models were used to create additional CFI metrics of initial level (intercept) and change (slope) in RT across accurate trials by easy (Color-X) and difficult (Color-Word) conditions. Models were adjusted for race, sex, age, income, major morbidities, depressive symptoms, self-reported health, and Stroop interference (for Color-Word condition only).Results: All CFI RT metrics were associated with SPPB <9, yet latent growth model approaches were most informative. Initial levels of performance on easy (Risk Ratio, [RR] = 1.24; 95% Confidence Interval, [CI]: 1.03, 1.49) and difficult conditions (RR = 1.22; 95% CI: 1.05, 1.41), not rates of learning (slope) (RR = 1.08, 95% CI: 0.81, 1.45 and RR = 1.11, 95% CI: 0.96, 1.27 respectively), were associated with worse physical functioning.Conclusions: The association between the CFI and physical functioning demonstrates the interplay of cognitive frailty and worse objective mobility within a sociodemographic at-risk sample.

Influência da escolaridade de idosas nos ganhos de função executiva após treino de dupla tarefa

Resumo Objetivo Investigar a influência da escolaridade nos ganhos de função executiva após o treinamento com dupla tarefa (DT). Método Estudo exploratório realizado com 31 idosas, com escolaridade ≥3 anos e sem alterações das funções cognitivas rastreadas pelo Miniexame do Estado Mental (MEEM). As participantes foram distribuídas em dois grupos a partir do critério escolaridade, sendo o Grupo 1 com escolaridade de três a sete anos (n=17) e o Grupo 2 com escolaridade igual e superior a oito anos (n=14). Foram avaliadas as funções executivas antes e após o treinamento através dos testes Stroop, Exame Cognitivo de Addenbrooke - Revisado (ACE-R) e Trilhas B. O protocolo de intervenção consistiu em três sessões semanais, duração de 50 minutos cada, com a realização de atividades de DT cognitiva e motora, associadas à caminhada, por 12 semanas. Resultados A ANOVA indicou que o treinamento de DT melhorou significativamente o desempenho nos testes Stroop (F=5,95; p=0,02) e ACE-R (F=18,33; p<0,0001), independentemente da escolaridade. Foi verificado efeito do grupo nos testes ACE-R (F=14,65; p<0,001) e Trilhas B (F=18,74; p<0,001). Em nenhum dos testes analisados, foi observado efeito da interação grupo x tempo (0,04<F<2,14; 0,15<p<0,95). Conclusão O treinamento de DT pode melhorar significativamente a função executiva de idosas, independente do nível de escolaridade, podendo ser utilizado na prática clínica como uma proposta de intervenção, visando o ganho de função executiva.

Accelerated decline in cognition in a mouse model of increased oxidative stress

Mice deficient in the antioxidant enzyme Cu/Zn-superoxide dismutase (Sod1KO mice) have a significant reduction in lifespan, exhibit many phenotypes of accelerated aging, and have high levels of oxidative stress in various tissues. Age-associated cognitive decline is a hallmark of aging and the increase in oxidative stress/damage with age is one of the mechanisms proposed for cognitive decline with age. Therefore, the goal of this study was to determine if Sod1KO mice exhibit an accelerated loss in cognitive function similar to that observed in aged animals. Cognition was assessed in Sod1KO and wild type (WT) mice using an automated home-cage testing apparatus (Noldus PhenoTyper) that included an initial discrimination and reversal task. Comparison of the total distance moved by the mice during light and dark phases of the study demonstrated that the Sod1KO mice do not show a deficit in movement. Assessment of cognitive function showed no significant difference between Sod1KO and WT mice during the initial discrimination phase of learning. However, during the reversal task, Sod1KO mice showed a significantly greater number of incorrect entries compared to WT mice indicating a decline in cognition similar to that observed in aged animals. Markers of oxidative stress (4-Hydroxynonenal, 4-HNE) and neuroinflammation [proinflammatory cytokines (IL6 and IL-1β) and neuroinflammatory markers (CD68, TLR4, and MCP1)] were significantly elevated in the hippocampus of male and female Sod1KO compared to WT mice. This study provides important evidence that increases in oxidative stress alone are sufficient to induce neuroinflammation and cognitive dysfunction that parallels the memory deficits seen in advanced aging and neurodegenerative diseases.

Predictors of instrumental activities of daily living in community-dwelling older adults

Psychiatric mental health clinicians often rely on proxy and self-report evaluations to determine the cognitive function of older adults however, performance measures have greater accuracy and predictive ability for everyday function. This study tested physical and cognitive predictors of functional abilities in fifty-one community residing older adults. We administered a computerized battery of executive function tasks, a performance-based measure of instrumental activities of daily living (IADL), and three physical function measures (grip strength, 30-second Chair Stand Test, and 8-foot Up and Go). Regression models assessed the associations of three components of executive function (updating, shifting, and inhibition) with IADLs and physical functions. Updating was a significant predictor of the Medications and Financial DAFS scores and of grip strength. Shifting also predicted grip strength. In conclusion, different executive functions predict different domains of IADL functioning. Working memory was a robust predictor of IADL functioning in older adults, especially medication management skills.

Gait parameters and characteristics associated with increased risk of falls in people with dementia: a systematic review

BACKGROUND

People with dementia fall twice as often and have more serious fall-related injuries than healthy older adults. While gait impairment as a generic term is understood as a fall risk factor in this population, a clear elaboration of the specific components of gait that are associated with falls risk is needed for knowledge translation to clinical practice and the development of fall prevention strategies for people with dementia.

OBJECTIVE

To review gait parameters and characteristics associated with falls in people with dementia.

METHODS

Electronic databases CINAHL, EMBASE, MedLine, PsycINFO, and PubMed were searched (from inception to April 2017) to identify prospective cohort studies evaluating the association between gait and falls in people with dementia.

RESULTS

Increased double support time variability, use of mobility aids, walking outdoors, higher scores on the Unified Parkinson's Disease Rating Scale, and lower average walking bouts were associated with elevated risk of any fall. Increased double support time and step length variability were associated with recurrent falls. The reviewed articles do not support using the Performance Oriented Mobility Assessment and the Timed Up-and-Go tests to predict any fall in this population. There is limited research on the use of dual-task gait assessments for predicting falls in people with dementia.

CONCLUSION

This systematic review shows the specific spatiotemporal gait parameters and features that are associated with falls in people with dementia. Future research is recommended to focus on developing specialized treatment methods for these specific gait impairments in this patient population.

The Intersection of Physical Function, Cognitive Performance, Aging, and Multiple Sclerosis: A Cross-sectional Comparative Study

OBJECTIVE

To examine the associations between physical function (walking speed and endurance and functional mobility) and cognitive function (information processing speed and verbal memory) in older adults with multiple sclerosis (MS) and healthy controls.

BACKGROUND

Older adults with MS have worse physical and cognitive function than older adults without MS and young and middle-aged adults with MS. To date, little is known about the associations between, or coupling of, physical and cognitive function outcomes in older adults with MS.

METHODS

We administered physical and cognitive function measures to 40 older adults with MS and 40 demographically matched healthy controls. Pearson product moment correlations were used to examine bivariate linear relationships in the overall sample and in the subsamples of (a) older adults with MS and (b) healthy controls. Linear regression analyses were used to examine the independent associations between demographic characteristics and physical and cognitive function variables in the two subsamples.

RESULTS

In the overall sample, all physical function variables were significantly correlated with cognitive function, as measured by information processing speed, and these correlations were mainly due to the subsample of older adults with MS. The linear regression analyses further indicated that information processing speed and years of education consistently explained variance in all physical function variables, beyond the influence of demographic variables, in older adults with MS.

CONCLUSIONS

Physical function and information processing speed are strongly correlated in older adults with MS. Future research should examine underlying neurobehavioral mechanisms associated with physical and cognitive function as well as behavioral strategies for jointly improving these functions in older adults with MS.

Cognitive Function as a Predictor of Major Mobility Disability in Older Adults: Results From the LIFE Study

Background and Objectives

Many cross-sectional studies have confirmed a link between gait speed and cognitive function. However, it is unknown whether cognitive function plays a role in the onset of major mobility disability (MMD) and if the effects are independent of physical function. This study examined cognitive and physical function as predictors of MMD across an average of 2.6 years of follow-up in community-dwelling older adults with compromised mobility.

Research Design and Method

Data were collected from 1,635 participants in the Lifestyle Interventions and Independence for Elders (LIFE) study ages 70–89 years free of MMD at baseline. MMD was assessed every 6 months and defined as the inability to walk 400 m in ≤15 min without assistance or sitting. Cognitive function was assessed at baseline, 18 months, and 24 months using a cognitive battery categorized into four domains: global cognitive function, processing speed, verbal memory, and executive function.

Results

Across the study duration of 2.6 years, 536 participants (32.8%) developed MMD. Cox Proportional Hazard models indicated a protective relationship for higher baseline processing speed (Hazard Ratio [HR] per standard deviation: 0.86, p = .006), executive function (HR: 0.86, p = .002), and global cognition (HR: 0.85, p = .001) on incidence of MMD adjusted for demographics, intervention, and comorbidities. Results were not significant after adjustment for gait speed. In adjusted longitudinal models, a positive change in processing speed was significantly associated with reduced risk of MMD (HR: 0.52, p < .001) while other domains were not.

Discussion and Implications

In the LIFE study, processing speed at baseline and follow-up was a significant predictor of subsequent MMD although the observed association may be explained by physical function as reflected in gait speed. More studies are needed to understand how cognitive function, alone and in combination with physical function, influences risk of MMD.

The neural correlates of discrete gait characteristics in ageing: A structured review

Gait is complex, described by diverse characteristics underpinned by widespread central nervous system networks including motor and cognitive functions. Despite this, neural substrates of discrete gait characteristics are poorly understood, limiting understanding of gait impairment in ageing and disease. This structured review aims to map gait characteristics, defined from a pre-specified model reflecting independent gait domains, to brain imaging parameters in older adults. Fifty-two studies of 38,029 yielded were reviewed. Studies showed inconsistent approaches when mapping gait assessment to neural substrates, limiting conclusions. Gait impairments typically associated with brain deterioration, specifically grey matter atrophy and white matter integrity loss. Gait velocity, a global measure of gait control, was most frequently associated with these imaging markers within frontal and basal ganglia regions, and its decline predicted from white matter volume and integrity measurements. Fewer studies assessed additional gait measures or functional imaging parameters. Future studies mapping regional neuroanatomical and functional correlates of gait are needed, including those which take a multi-process network perspective to better understand mobility in health and disease.

Does poor sleep impair cognition during aging? Longitudinal associations between changes in sleep duration and cognitive performance among older Mexican adults

Alterations in sleep patterns are common among older adults; further, short and long sleep durations have been linked with impaired cognitive performance in older individuals. Yet most research examining these relationships has been cross-sectional, limited to high-income nations, and has failed to consider how changes in sleep duration may impact cognitive decline. The present longitudinal study uses nationally-representative data to test whether changes in sleep length among "healthy" baseline sleepers are associated with reduced cognitive function in older Mexican adults (>50 years old) at follow-up. Data were drawn from the first and second waves of the World Health Organization's Study on global AGEing and adult health. Self-report data captured sleep duration over two nights, and five cognitive tests (immediate and delayed verbal recall, forward and backward digit span, and verbal fluency) were used to measure various cognitive domains and create a composite z-score of cognitive performance. Linear regressions were performed to assess associations between sleep length changes and cognitive decline, controlling for relevant lifestyle and health factors. Increased sleep durations at follow-up among individuals who reported intermediate sleep durations (6-9 h/night) at baseline were significantly associated with greater rates of decline in overall cognitive function. Longer sleepers also trended toward greater rates of decline for attention/working memory and executive function. This study suggests that long sleep durations are a risk factor for certain types of impaired cognition among older adults living in a middle-income country. These findings are clinically important given the growing rates of dementia and aging populations globally.

Sarcopenia Is Associated with Cognitive Impairment Mainly Due to Slow Gait Speed: Results from the Korean Frailty and Aging Cohort Study (KFACS)

Sarcopenia and cognitive impairment may share common risk factors and pathophysiological pathways. We examined the association between impairments in specific cognitive domains and sarcopenia (and its defining components) in community-dwelling older adults. We analyzed 1887 patients who underwent cognitive function tests and dual-energy X-ray absorptiometry from the baseline data of adults aged 70-84 years obtained from the Korean Frailty and Aging Cohort Study. Those with disability in activities of daily living, dementia, severe cognitive impairment, Parkinson's disease, musculoskeletal complaints, neurological disorders, or who were illiterate were excluded. Cognitive function was assessed using the Korean version of the Consortium to Establish a Registry for Alzheimer's Disease Assessment Packet, the Frontal Assessment Battery. For sarcopenia, we used the diagnostic criteria of the Asian Working Group for Sarcopenia. The prevalence of sarcopenia was 9.6% for men and 7.6% for women. Sarcopenia (odds ratio [OR] 1.76, 95% confidence interval [CI] 1.04-2.99) and slow gait speed (OR 2.58, 95% CI 1.34-4.99) were associated with cognitive impairment in men. Only slow gait speed (OR 1.88, 95% CI 1.05-3.36) was associated with cognitive impairment in women. Sarcopenia is associated with cognitive impairment mainly due to slow gait speed. Our results suggested that cognitive impairment domains, such as processing speed and executive function, are associated with sarcopenia-related slow gait speed.

Incident Mobility Disability, Mild Cognitive Impairment, and Mortality in Community-Dwelling Older Adults

BACKGROUND/AIMS

Mobility disability and mild cognitive impairment (MCI) are common in aging and both are associated with risk of death. This study tested the hypothesis that risk of death differs by the order in which mobility disability and MCI occurred.

METHODS

One thousand two hundred and sixty-two community-dwelling older adults were unimpaired at baseline and followed annually. Mobility disability was based on measured gait speed, and MCI was based on cognitive performance tests. A multistate Cox model simultaneously examined incidences of mobility disability and MCI to determine whether the order of their occurrence is differentially associated with risk of death.

RESULTS

The average age was 75.3 years and 70% were female. While mobility disability occurred more frequently than incident MCI, the subsequent risk of death was higher in participants who developed MCI alone compared to those who developed mobility disability alone (hazard ratio [HR] 1.70, p = 0.018). Of the participants who initially developed mobility disability, about half subsequently developed MCI that doubled their risk of death (HR 2.17, p < 0.001). By contrast, over two-third who developed MCI subsequently developed mobility disability, which did not further increase their risk of death.

CONCLUSION

Mobility disability occurs more frequently in community-dwelling older adults, but MCI is more strongly associated with mortality.

Gray matter volume covariance patterns associated with gait speed in older adults: a multi-cohort MRI study

Accelerated gait decline in aging is associated with many adverse outcomes, including an increased risk for falls, cognitive decline, and dementia. Yet, the brain structures associated with gait speed, and how they relate to specific cognitive domains, are not well-understood. We examined structural brain correlates of gait speed, and how they relate to processing speed, executive function, and episodic memory in three non-demented and community-dwelling older adult cohorts (Overall N = 352), using voxel-based morphometry and multivariate covariance-based statistics. In all three cohorts, we identified gray matter volume covariance patterns associated with gait speed that included brain stem, precuneus, fusiform, motor, supplementary motor, and prefrontal (particularly ventrolateral prefrontal) cortex regions. Greater expression of these gray matter volume covariance patterns linked to gait speed were associated with better processing speed in all three cohorts, and with better executive function in one cohort. These gray matter covariance patterns linked to gait speed were not associated with episodic memory in any of the cohorts. These findings suggest that gait speed, processing speed (and to some extent executive functions) rely on shared neural systems that are subject to age-related and dementia-related change. The implications of these findings are discussed within the context of the development of interventions to compensate for age-related gait and cognitive decline.

Talk or Walk? Gait Speed over Self-Report in Association with Cognitive Speed in Healthy Older Adults

Abstract. This study explores the relative value of both subjectively reported cognitive speed and gait speed in association with objectively derived cognitive speed. It also explores how these factors are affected by psychological and physical well-being. A group of 90 cognitively healthy older adults ( M = 73.38, SD = 8.06 years, range = 60–89 years) were tested in a three-task cognitive battery to determine objective cognitive speed as well as measures of gait speed, well-being, and subjective cognitive speed. Analyses indicated that gait speed was associated with objective cognitive speed to a greater degree than was subjective report, the latter being more closely related to well-being than to objective cognitive speed. These results were largely invariant across the 30-year age range of our older adult sample.

What features of the built environment matter most for mobility? Using wearable sensors to capture real-time outdoor environment demand on gait performance

BACKGROUND

A growing body of research has demonstrated relationships between built environment characteristics and outdoor mobility. However, most of this work has relied on composite scores of the built environment.

RESEARCH QUESTION

Which properties of the outdoor built environment are associated with the greatest change in gait metrics in a real-world setting?

METHODS

25 community-dwelling adults from Southeast Michigan were equipped with mobile inertial measurement units and walked a 1300-meter outdoor course with varying environmental demands. Environmental properties were documented in sections of the course using the Senior Walking Environmental Assessment Tool. Gait speed, left foot cadence, and stride length were used to identify the built environment properties under which mobility was most challenged using linear mixed models. We hypothesized that subjects would adapt to demanding environments by decreasing gait speed, increasing cadence, and shortening stride length.

RESULTS

Properties of the built environment were significantly associated with changes in gait speed, left foot cadence, and stride length. Properties that were most important for predicting gait speed included slope, sidewalk condition, and presence of holes. Sidewalk slope, bumps, and the presence of a curb cut were all significant predictors of left foot cadence. Mean stride length of the outdoor course was significantly associated with the section's condition, slope, holes, bumps, width, and the presence of grooves and bumps at a curb.

SIGNIFICANCE

Associations between environmental properties and gait parameters were differential across the three mobility outcomes. When examining which properties of the built environment are challenging to navigate it is important to understand the relative influence of specific properties on gait metrics. Knowledge of which built environment properties are barriers for walking behavior is critical for the design of inclusive sidewalks and streets.

Effects of aerobic fitness on cognitive performance as a function of dual-task demands in older adults

The objective of this study was to examine the effects of aerobic fitness on cognitive performance under varying dual-task demands in older adults. Thirty-four participants (mean ± SD age: 68.6 ± 10.1 years, 24 females) were included in this study. VO₂ max was assessed with the Rockport 1-mile walk test (range = 6.68-45.57). Participants engaged in a cognitive task, the Modified Stroop Color Word Test (MSCWT) on a self-paced treadmill while simultaneously standing or walking. Performance on the Stroop Test was measured as interference of the accuracy score. Participants demonstrated over a 4-fold increase in SI when going from Incongruent to Switching MSCWT blocks across both standing and walking tasks. Furthermore, there was a significant interaction between the MSCWT block and VO₂ max in Stroop interference, such that Switching Stroop interference demonstrated greater changes due to VO₂ max, in comparison to Incongruent SI, even after controlling for age, gender, body mass index, and years of education as covariates in analyses. These results provide evidence of a relationship between aerobic fitness and cognition, suggesting that dual-task interference may provide a sensitive indicator of effects of an aerobic intervention program on the cognitive performance among older adults.

Longitudinal association between brain volume change and gait speed in a general population

OBJECTIVE

To determine the association between brain structural changes and gait speed in a four-year longitudinal prospective cohort study.

MEASUREMENTS

A total of 767 well-functioning community-dwelling participants, free of arthritis, silent infarct, stroke, dementia, head injury, and cancer, completed baseline brain magnetic resonance imaging scan and gait speed tests between 2011 and 2014, and follow-up tests between 2015 and 2017. The gait test consisted of measuring the elapsed time to walk four meters at usual speed. To estimate whether brain volume changes predict gait speed decline at follow-up, a generalized linear regression model was used after adjusting for potential confounding factors including gait speed at baseline.

RESULTS

Participants who experienced ≥0.05 m/s gait speed decline, previously defined as a clinically meaningful decline, were more likely to be women, less likely to be smokers, and had lower physical activity scores (p = 0.003, p = 0.025, and p = 0.006, respectively), as compared to those who did not experience the decline. Also, they demonstrated smaller volumes of hippocampus, total gray matter, parietal gray matter, temporal gray matter, and temporal white matter (p = 0.004, p = 0.042, p = 0.021, p = 0.001, and p = 0.004, respectively). Even after correcting the significance level due to multiple comparisons, overall gray matter and overall white matter volume changes during four-year follow-up period showed significant associations with gait speed at follow-up (p < 0.001 and p = 0.002). Regarding region-specific volumes, frontal white matter and parietal gray matter volume changes demonstrated significant associations with gait speed (p = 0.002, p = 0.004, respectively).

CONCLUSION

In a four-year longitudinal study among 767 well-functioning community-dwelling healthy participants from a general population, we observed a significant association between brain volume changes and gait speed.

Cognitive-Based E-Learning Design for Older Adults

Aging is highly correlated with a decline in cognitive abilities. Information and communication technologies are nowadays increasingly used for knowledge acquisition, education, cognitive development, etc. Older adults should be prepared to adopt these technologies and take advantage of their capabilities. The purpose of this study was to analyze the cognitive profile of older adults in order to identify the ways that they learn, as well as to analyze older adults’ attitudes, to aid in the development of an e-learning platform adapted to their needs. The sample of the study consisted of 103 older adults, aged 55+, from Greece. According to their responses, older adults seemed to prefer e-learning modules that presented the educational content step-by-step and contained practice questions and examples. In addition, respondents had positive attitudes toward the existence of assessment tests for after the completion of each module. Finally, the utilization of explanatory videos and special graphics in the modules was imperative, according to older adults’ preferences.

Physical performance and cognitive functioning among individuals with diabetes: Findings from the China Health and Retirement Longitudinal Study Baseline Survey

AIMS

The purpose of this study was to examine individual associations of each physical performance measure with domains of cognitive functioning and to determine best physical performance measures strongly associated with each domain of cognitive functioning among middle-aged and older adults with diabetes.

BACKGROUND

Tests of physical performance are strongly correlated with cognitive decline in general elderly population. However, far less is known about individual associations of each individual physical performance measure with domains of cognitive functioning among individuals with diabetes.

DESIGN

The study employed a retrospective, cross-sectional design.

METHODS

Baseline data from a national baseline survey collected from May 2011-March 2012 were used. A total of 17,314 individuals aged ≥45 years completed the baseline survey. Diabetes was confirmed for 1,905 participants and these individuals were included in this study.

RESULTS

When grip strength, walking speed, repeated chair stands and standing balance test were added in the regression models, walking speed was the only variable that was significantly associated with figure drawing and grip strength was the only variable that was significantly associated with episodic memory, orientation/attention and overall cognitive score.

CONCLUSION

Since grip strength was the most important factor associated with several domains of cognitive functioning, strategies that improve grip strength in patients with diabetes are prudent. Early interventions to increase levels of physical activity may be important to improve both grip strength and cognitive functioning in this growing population with diabetes.

Associations of literacy with diabetes indicators in older adults

BACKGROUND

Literacy, the ability to access, understand and utilise information and concepts from diverse sources in ways that promote good outcomes is key to successful ageing. Domain-specific health and financial literacy are particularly relevant to older adults as they face increasingly complex health and financial demands including those related to chronic conditions like type 2 diabetes. We therefore investigated the associations of literacy, including health and financial literacy, with diabetes indicators (ie, haemoglobin A1c and blood glucose) in a community-based cohort study of ageing.

METHODS

Participants were 908 non-demented older adults (age ~81 years;75% women) from the Rush Memory and Aging Project. Literacy was measured using questions designed to assess comprehension of health and financial information and concepts and yielded a total score and domain-specific health and financial literacy scores. Non-fasting haemoglobin A1c and blood glucose samples were collected, participants were queried about diabetes status and medications for diabetes were visually inspected and coded. Participants also underwent a cognitive assessment, medical history and depressive symptom screening.

RESULTS

In separate multivariable linear regression models, total (p values <0.03) and health (p values <0.009) literacy were inversely associated with haemoglobin A1c and blood glucose levels after adjusting for age, sex, education, hypertension, global cognitive functioning and depressive symptoms. Financial literacy was inversely associated with haemoglobin A1c levels in adjusted models (p=0.04). Sensitivity analyses conducted among individuals without diabetes revealed similar results.

CONCLUSION

Lower literacy levels are associated with higher diabetes indicators, particularly haemoglobin A1c which is suggestive of longer-term glycaemic instability.

High Intensity Jump Exercise Preserves Posture Control, Gait, and Functional Mobility During 60 Days of Bed-Rest: An RCT Including 90 Days of Follow-Up

Physical inactivity causes a deconditioning of the human body. Concerns due to chronic bed-rest include deficits in posture and gait control, predisposing individuals to an increased fall and injury risk. This study assessed the efficiency of a high-load jump exercise (JUMP) as a countermeasure to prevent detrimental effects on gait, posture control and functional mobility. In an RCT (23 males), the effect of 60 days bed-rest without training was compared to JUMP. JUMP is characterized by plyometric executed as a high intensity interval training. Typical trainings session consisted of 4 × 10 countermovement jumps and 2 × 10 hops in a sledge jump system. We assessed sway path and muscle activity in monopedal stance, spatiotemporal, kinematic, and variability characteristics in gait, functional mobility with repeated chair-rises and Timed Up and Go (TUG). Results revealed: The JUMP group showed no significant changes after bed-rest, whereas the control group exhibited substantial deteriorations: an increased sway path (+104%, p < 0.05) was accompanied by increased co-contractions of antagonistic muscles encompassing the ankle (+32%, p < 0.05) and knee joint (45%, p < 0.05). A reduced locomotor speed (−22%, p < 0.05) was found concomitant with pathological gait rhythmicity (p < 0.05), reduced joint excursions (ankle −8%, knee −29%, p < 0.05) and an increased gait variability (p < 0.05). Chair-rising was slowed (+28%, p < 0.05) with reduced peak power (+18%, p < 0.05), and more time was needed to accomplish TUG (+39%, p < 0.05). The effects persisted for a period of 1 month after bed-rest. Increases in sway path were correlated to decreases in gait speed. The JUMP effectively preserved the neuromuscular system's ability to safely control postural equilibrium and perform complex locomotor movements, including fast bipedal gait with turns and rises. We therefore recommend JUMP as an appropriate strategy combatting functional deconditioning.

Reliability, validity and minimal detectable change of 2-minute walk test, 6-minute walk test and 10-meter walk test in frail older adults with dementia

BACKGROUND

Walk tests are commonly used to evaluate walking ability in frail older adults with dementia but their psychometric evidence in this population is lacking.

OBJECTIVES

1) To examine test-retest and inter-rater reliability, construct and known-group validity, and minimal detectable change at 95% level of confidence (MDC₉₅) of walk tests in frail older adults with dementia, and 2) to examine the feasibility and consistency of a cueing system in facilitating participants in completing walk tests.

DESIGN

Psychometric study with repeated measures.

SETTING

Day care and residential care facilities.

PARTICIPANTS

Thirty-nine frail older adults with a mean age 87.1 and a diagnosis of dementia or Alzheimer's disease who were able to walk independently for at least 15 m.

METHODS

The participants underwent a 2-minute walk test (2MWT), 6-minute walk test (6MWT) and 10-meter walk test (10MeWT) on 6 separate occasions under 2 independent assessors using a cueing system. Functional status was measured using the Elderly Mobility Scale (EMS), Berg Balance Scale (BBS) and Modified Barthel Index (MBI).

RESULTS

Excellent test-retest (ICC = 0.91-0.98) and inter-rater reliability (ICC = 0.86-0.96) were shown in the 2MWT, 6MWT and 10MeWT. The walk tests were strongly correlated with each other (ρ = 0.85-0.94). The correlations between the walk tests and the functional measures were moderate in general (ρ = 0.34-0.55). All the walk tests were able to distinguish between those who could walk outdoor and indoor only (p ≤ .036). The MDC₉₅ were 9.1 m in the 2MWT, 28.1 m in the 6MWT, and.16 m/s in the 10MeWT. The cues provided by the assessors in the walk tests were generally consistent (ICC = 0.62-0.89).

CONCLUSIONS

The 2MWT, 6MWT and 10MeWT are reliable and valid measures in evaluating walking ability in frail older adults with dementia. The MDC₉₅ of the walk tests has been established. The cueing system is feasible and reliable to facilitate the administration of the walk tests in this population group.

Association between cognitive function and life-space mobility in older adults: results from the FRéLE longitudinal study

BACKGROUND

Cross-sectional and longitudinal studies show conflicting results regarding the association between cognition and life-space mobility, and little is known regarding the mediators and moderators of the association. The aim of this study was to investigate the association between cognition and life-space mobility in older adults, as well as the intervening variables modifying the relationship.

METHODS

Community-dwelling older adults aged 65 years and older (N = 1643) were assessed at three time points over a period of 2 years. Growth mixture models with mediation and moderation analysis were utilised to investigate association between cognitive function and life-space mobility. The potential mediators and moderators were depressive symptoms, locus of control, gait speed and grip strength. Analysis was controlled for age, sex, education, annual income, number of chronic illnesses, and living site.

RESULTS

The direct association between initial scores of cognitive function and life-space was mediated by initial scores of depressive symptoms and gait speed, and moderated by initial scores of grip strength. No direct association between change in cognitive function and change in life-space mobility was found; the scores were mediated by change in depressive symptoms.

CONCLUSIONS

We conclude that the relationship between change in cognitive function and life-space mobility in older adults is not well-defined over an observation period of 2 years.

Association between brain atrophy and cognitive motor interference in multiple sclerosis

INTRODUCTION

Cognitive motor interference (CMI) is performance impairment due to simultaneuous task execution and is measured using the dual task cost (DTC). No pathological feature of MS has to date been associated with CMI.

AIM

To assess the relationship between brain volumes and CMI, as measured using the DTC, in a cross-sectional study.

METHODS

A group of persons with MS (pwMS) and an age- and sex-matched healthy control (HC) group underwent 3D gait analysis during using the dual task paradigm. Brain volumes were measured on T1-weighted gradient echo scans using SIENAX software. The relationships between brain volumes and the DTCs of spatial temporal parameters were evaluated using Pearson correlation. A multiple regression model was used to evaluate the ability to predict the DTC of cadence based on brain volume and grey matter (GM) volume.

RESULTS

Forty-four patients and 16 HCs underwent MRI and gait analysis. The mean expanded disability status scale (EDSS) was 2.4 ± 1.5. Significant relationships between brain volumes and DTC were found only in the pwMS group, with higher rho scores for the DTC of mean velocity, DTC of cadence, and DTC of stride time. A statistically significant regression equation with an R² value of 0.684 was found using GM and Z-score on the Stroop test as predictors of the DTC of cadence (p < 0.001).

CONCLUSION

Brain atrophy, especially than in the GM, is a major determinant of DTC, although other pathological markers also contribute to CMI in patients with MS.

Locus of control as a modifiable risk factor for cognitive function in midlife

Few modifiable risk factors for cognitive decline have been identified. Despite an external locus of control (LoC) being adversely associated with many psychological and physical health outcomes, few studies have examined whether it is related to cognitive function in adulthood. In 1178 women from the Avon Longitudinal Study of Parents and Children, we examined whether LoC, and change in LoC over time, is associated with cognitive function in midlife. LoC was prospectively measured at mean ages 30 and 48 years using the validated Nowicki-Strickland scale. Cognitive function was examined at mean age 51 years. At both time points, greater externality was associated with lower cognitive function. For example, the group of women classified as being external at mean age 48 years had, on average, a 0.18 lower cognitive function score (95% CI: (0.11 to 0.25) than the group classified as being internal (p<0.001). Participants who changed from external to internal over time, on average, had better cognitive function than those who remained external or changed to become external. In summary, an external LoC may be detrimental to cognitive function. Thus, interventions to increase internality may help to minimise the adverse consequences on cognitive health later in life.

Physical Predictors of Cognitive Function in Individuals With Hypertension: Evidence from the CHARLS Basline Survey

The purpose of the study was to examine the independent associations of each individual physical performance measure (i.e., grip strength, walking speed, repeated chair stands, and balance test) with subdomains of cognitive function and to determine predictors for each subdomain of cognitive function. A secondary data analysis was performed using a nationally representative middle-aged and older sample of hypertensive population. The findings showed that after adding all four physical performance measures, stronger grip strength was significantly associated with better visuospatial abilities, episodic memory, orientation/attention, and overall cognitive function. In addition, faster walking speed and faster repeated chair stands were strongly associated with better episodic memory and overall cognitive function, respectively. Because grip strength was significantly associated with several subdomains of cognitive functioning, it seems conceivable that increasing physical activity would improve both grip strength and cognitive function in patients with hypertension.

Simultaneous assessment of cognitive function, circadian rhythm, and spontaneous activity in aging mice

Cognitive function declines substantially with age in both humans and animal models. In humans, this decline is associated with decreases in independence and quality of life. Although the methodology for analysis of cognitive function in human models is relatively well established, similar analyses in animal models have many technical issues (e.g., unintended experimenter bias, motivational issues, stress, and testing during the light phase of the light dark cycle) that limit interpretation of the results. These caveats, and others, potentially bias the interpretation of studies in rodents and prevent the application of current tests of learning and memory as part of an overall healthspan assessment in rodent models of aging. The goal of this study was to establish the methodology to assess cognitive function in aging animals that addresses many of these concerns. Here, we use a food reward-based discrimination procedure with minimal stress in C57Bl/6J male mice at 6, 21, and 27 months of age, followed by a reversal task to assess behavioral flexibility. Importantly, the procedures minimize issues related to between-experimenter confounds and are conducted during both the dark and light phases of the light dark cycle in a home-cage setting. During cognitive testing, we were able to assess multiple measures of spontaneous movement and diurnal activity in young and aged mice including, distance moved, velocity, and acceleration over a 90-h period. Both initial discrimination and reversal learning significantly decreased with age and, similar to rats and humans, not all old mice demonstrated impairments in learning with age. These results permitted classification of animals based on their cognitive status. Analysis of movement parameters indicated decreases in distance moved as well as velocity and acceleration with increasing age. Based on these data, we developed preliminary models indicating, as in humans, a close relationship exists between age-related movement parameters and cognitive ability. Our results provide a reliable method for assessing cognitive performance with minimal stress and simultaneously provide key information on movement and diurnal activity. These methods represent a novel approach to developing non-invasive healthspan measures in rodent models that allow standardization across laboratories.

Characterisation of Physical Frailty and Associated Physical and Functional Impairments in Mild Cognitive Impairment

Objective

To characterize the physical frailty phenotype and its associated physical and functional impairments in mild cognitive impairment (MCI).

Method

Participants with MCI (N = 119), normal low cognition (NLC, N = 138), and normal high cognition (NHC, N = 1,681) in the Singapore Longitudinal Ageing Studies (SLAS-2) were compared on the prevalence of physical frailty, low lean body mass, weakness, slow gait, exhaustion and low physical activity, and POMA balance and gait impairment and fall risk.

Results

There were significantly higher prevalence of frailty in MCI (18.5%), than in NLC (8.0%) and NHC (3.9%), and pre-frailty in MCI (54.6%), NLC (52.9%) than in NHC (48.0%). Age, sex, and ethnicity-adjusted OR (95% CI) of association with MCI (versus NHC) for frailty were 4.65 (2.40–9.04) and for pre-frailty, 1.67 (1.07–2.61). Similar significantly elevated prevalence and adjusted ORs of association with MCI were observed for frailty-associated physical and functional impairments. Further adjustment for education, marital status, living status, comorbidities, and GDS significantly reduced the OR estimates. However, the OR estimates remained elevated for frailty: 3.86 (1.83–8.17), low body mass: 1.70 (1.08–2.67), slow gait: 1.84 (1.17–2.89), impaired gait: 4.17 (1.98–8.81), and elevated fall risk 3.42 (1.22–9.53).

Conclusion

Two-thirds of MCI were physically frail or pre-frail, most uniquely due to low lean muscle mass, slow gait speed, or balance and gait impairment. The close associations of frailty and physical and functional impairment with MCI have important implications for improving diagnostic acuity of MCI and targetting interventions among cognitively frail individuals to prevent dementia and disability.

Pharmacologically induced impairment of neurovascular coupling responses alters gait coordination in mice

There is correlative evidence that impaired cerebral blood flow (CBF) regulation, in addition to promoting cognitive impairment, is also associated with alterations in gait and development of falls in elderly people. CBF is adjusted to neuronal activity via neurovascular coupling (NVC) and this mechanism becomes progressively impaired with age. To establish a direct cause-and-effect relationship between impaired NVC and gait abnormalities, we induced neurovascular uncoupling pharmacologically in young C57BL/6 mice by inhibiting the synthesis of vasodilator mediators involved in NVC. Treatment of mice with the epoxygenase inhibitor MSPPOH, the NO synthase inhibitor L-NAME, and the COX inhibitor indomethacin significantly decreased NVC mimicking the aging phenotype. Pharmacologically induced neurovascular uncoupling significantly decreased the dynamic gait parameter duty cycle, altered footfall patterns, and significantly increased phase dispersion, indicating impaired interlimb coordination. Impaired NVC also tended to increase gait variability. Thus, selective experimental disruption of NVC causes subclinical gait abnormalities, supporting the importance of CBF in both cognitive function and gait regulation.

Dual-task during gait between elderly with mild cognitive impairment and Alzheimer: systematic review

Abstract Introduction: Studies report that mobility changes could be present in early stages of Alzheimer’s disease (AD) or even in previous stages, such as mild cognitive impairment (MCI). The use of motor tests, involving dual task, could facilitate screening and differentiation between elderly with AD and MCI. Objective: to verify if gait tests associated with secondary tasks could differentiate elderly with AD and MCI. Methods: We conducted a systematic review in Pubmed, Web of Science, Medline and Scielo databases. Of the articles included, we collected information about year of the study, characteristics of the sample and the dual task test studied. Results: The databases were accessed during November 2014 and August 2015 and a total of 198 scientific papers was obtained. After reading first the summaries and then the full texts, five studies were inserted in the review. Elderly with AD presented a reduction of gait speed and stride length, using executive functions and countdown as secondary cognitive tasks. The type of MCI appears to influence the differentiation with AD. Conclusion: The review showed that some gait tests associated with a secondary task differentiate elderly with AD and MCI. It emphasizes the need of new studies involving this issue in order to obtain cut-off points and facilitate prevention, early diagnosis and observation of cognitive impairment’s evolution in clinical practice of elderly.

Motor deficits are independent of axonopathy in an Alzheimer's disease mouse model of TgCRND8 mice

There have been an increasing number of reports of non-cognitive symptoms in Alzheimer's disease (AD). Some symptoms are associated with the loss of motor functions, e.g. gait disturbances, disturbed activity level and balance. Consistent with clinical findings, several AD mouse models harboring amyloid pathology develop motor impairment. Although the factors that contribute to the motor deficits have not yet been determined, it has been suggested that axonopathy is one of the key factors that may contribute to this particular feature of the disease. Our previous study found that TgCRND8 mice exhibited profound motor deficits as early as 3 months old. In this study, we explored the possible factors that may be related to motor deficits in TgCRND8 mice. Results from silver, neurofilament and amyloid precursor protein (APP) staining revealed no axonopathy occurred in the brain and spinal cord of TgCRND8 mice at the age of 3 months. Anterograde labeling of corticospinal tract of spinal cord and electronic microscopy (EM) analysis showed that no axonopathy occurred in TgCRND8 mice at the age of 3 months. According to these results, it could be concluded that no axonal alterations were evident in the TgCRND8 mice when motor deficits was overt. Thus, axonopathy may play a less prominent role in motor deficits in AD. These results suggest that mechanisms by which motor function undergo impairment in AD need to be further studied.

Cognition, Health, and Well-Being in a Rural Sub-Saharan African Population

Cognitive health is an important dimension of well-being in older ages, but few studies have investigated the demography of cognitive health in sub-Saharan Africa's (SSA) growing population of mature adults (= persons age 45+). We use data from the Malawi Longitudinal Study of Families and Health (MLSFH) to document the age and gender patterns of cognitive health, the contextual and life-course correlates of poor cognitive health, and the understudied linkages between cognitive and physical/mental well-being. Surprisingly, the age-pattern of decline in cognitive health is broadly similar to that observed in the U.S. We also find that women have substantially worse cognitive health than men, and experience a steeper age-gradient in cognitive ability. Strong social ties and exposure to socially complex environments are associated with higher cognitive health, as is higher socioeconomic status. Poor cognitive health is associated with adverse social and economic well-being outcomes such as less nutrition intake, lower income, and reduced work efforts even in this subsistence agriculture context. Lower levels of cognitive health are also strongly associated with increased levels of depression and anxiety, and are associated with worse physical health measured through both self-reports and physical performance. Our findings suggest that cognition plays a key-but understudied-role in shaping late-life well-being in low-income populations.

The correlates of slow gait and its relation with social network among older adults in Singapore

OBJECTIVES

This study aimed to identify socio-demographic correlates of slow gait speed among Singapore older adult residents and to examine the relationship between slow gait speed and the older adult residents' social network, physical health status, disability and mental health status.

METHODS

Trained interviewers administered the adapted 10/66 research protocol through face-to-face interviews to 2565 respondents aged 60 and over. Information on gait test, socio-demographic characteristics, obesity, social network, physical status and activity, overall health, disability and mental health status were collected. The gait test was completed by 2192 participants. Slow gait was defined as walking speed of 1 standard deviation (SD) below age and gender specific mean gait of the sample.

RESULTS

The prevalence of slow gait speed after adjusting for age and gender was 13.7%. Slow gait speed was more prevalent among Indians, respondents with low education, and those who were retired. Those with slow gait speed were significantly associated with lower probability of being unemployed and attending religious activities. They were significantly associated with not being physically active and reported a higher disability score.

CONCLUSION

Older adult residents' socio-demographic factors were found to be associated with gait speed. Those with slow gait speed were not physically active and had less frequent contact with people through religious activities and this might place them at risk of being socially isolated, which can have consequences. Gait speed can be included as a routine assessment tool to identify at-risk groups for interventions which aim to keep the older adults socially engaged and healthy.