The Association Between Physical Activity and Cognition in a Racially/Ethnically Diverse Cohort of Older Adults: Results From the Kaiser Healthy Aging and Diverse Life Experiences Study

OBJECTIVE

Most prior research on physical activity (PA) and cognition is based on predominantly white cohorts and focused on associations of PA with mean (average) cognition versus the distribution of cognition. Quantile regression offers a novel way to quantify how PA affects cognition across the entire distribution.

METHODS

The Kaiser Healthy Aging and Diverse Life Experiences study includes 30% white, 19% black, 25% Asian, and 26% Latinx adults age 65+ living in Northern California (n = 1600). The frequency of light or heavy PA was summarized as 2 continuous variables. Outcomes were z-scored executive function, semantic memory, and verbal episodic memory. We tested associations of PA with mean cognition using linear regression and used quantile regression to estimate the association of PA with the 10th-90th percentiles of cognitive scores.

RESULTS

Higher levels of PA were associated with higher mean semantic memory (b = 0.10; 95% CI: 0.06, 0.14) and executive function (b = 0.05; 95% CI: 0.01, 0.09). Associations of PA across all 3 cognitive domains were stronger at low quantiles of cognition.

CONCLUSION

PA is associated with cognition in this racially/ethnically diverse sample and may have larger benefits for individuals with low cognitive scores, who are most vulnerable to dementia.

Effect of physical activity on risk of Alzheimer's disease: A systematic review and meta-analysis of twenty-nine prospective cohort studies

OBJECTIVE

Physical activity (PA) is beneficial in reductions of all-cause mortality and dementia. However, whether Alzheimer's disease (AD) risk is modified by PA remains disputable. This meta-analysis aims to disclose the underlying relationship between PA and incident AD.

METHODS

Pubmed, Embase, Cochrane Library, and Web of Science were retrieved from inception to June 2023. Random-effects models were employed to derive the effect size, represented by hazard ratio (HR) and 95% confidence interval (CI).

RESULTS

Twenty-nine prospective cohort studies involving 2068,519 participants were included. The pooled estimate showed a favorable effect of PA on AD risk decline (HR 0.72, 95% CI 0.65-0.80). This association remained robust after adjusting for maximum confounders (HR 0.85, 95% CI 0.79-0.91). Subgroup analysis of PA intensity demonstrated an inverse dose-response relationship between PA and AD, effect sizes of which were significant in moderate (HR 0.85, 95% CI 0.80-0.93) and high PA (HR 0.56, 95% CI 0.45-0.68), but not in low PA (HR 0.94, 95% CI 0.77-1.15). Regardless of all participants or the mid-life cohort, the protection of PA against AD appeared to be valid in shorter follow-up (<15 years) rather than longer follow-up (≥15 years). In addition to follow-up, the robustness of the estimates persisted in supplementary meta-analyses, meta-regression analyses, and sensitivity analyses.

CONCLUSION

PA intervention reduces the incidence of AD, but merely in moderate to vigorous PA with follow-up of less than 15 years, thus conditionally recommending the popularization of PA as a modifiable lifestyle factor to prevent AD.

Physical activity mitigates the influence of blood cadmium on memory function: a cross-sectional analysis in US elderly population

Current evidence showed that heavy metal exposure including cadmium (Cd) exposure might contribute to memory function impairment in youth, while this association has not been extensively explored in senior groups. Complementary therapy like physical activity (PA) is proved to enhance memory; however, the combined effects of Cd exposure and PA are interesting issues worth investigating. Cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 2011-2014 were analyzed. Multivariable weighted linear regression model and restricted cubic splines analysis were used to examine the association between blood Cd, PA, and memory function. Ultimately, 1884 samples were analyzed, and the weighted participants were 98,350,183. Results showed that in the immediate and delayed recall tests, a negative association was found between blood Cd and scores for the fully adjusted model, while a positive association was detected with PA on memory test scores. In subgroup analysis, for the delayed recall test, in lower Cd exposure (Cd = Q1), stronger effect size was found in the moderate level PA group than the higher level PA group (moderate level PA group, β = 1.133, 95% CI: 0.330, 1.936; high level PA group, β = 0.203, 95% CI: - 0.314, 0.719), and this finding also existed in higher (Cd = Q4) exposure (moderate level PA group, β = 0.988, 95% CI: 0.267, 1.708; high level PA group, β = 0.830, 95% CI: 0.261, 1.400). Moreover, the non-linear relationship between Cd exposure and performance of CERAD test under different levels of PA was reported, and the moderate level PA group performed best from lower to higher blood Cd. According to our research, the benefit of PA did not always expand with the PA intensity increment under different Cd exposure. Performing an appropriate level of physical exercise could alleviate the memory decline under Cd exposure in the elder groups. Further biological investigations are warranted to verify these findings.

Dose-response relationship between late-life physical activity and incident dementia: A pooled analysis of 10 cohort studies of memory in an international consortium

INTRODUCTION

Though consistent evidence suggests that physical activity may delay dementia onset, the duration and amount of activity required remains unclear.

METHODS

We harmonized longitudinal data of 11,988 participants from 10 cohorts in eight countries to examine the dose-response relationship between late-life physical activity and incident dementia among older adults.

RESULTS

Using no physical activity as a reference, dementia risk decreased with duration of physical activity up to 3.1 to 6.0 hours/week (hazard ratio [HR] 0.88, 95% confidence interval [CI] 0.67 to 1.15 for 0.1 to 3.0 hours/week; HR 0.68, 95% CI 0.52 to 0.89 for 3.1 to 6.0 hours/week), but plateaued with higher duration. For the amount of physical activity, a similar pattern of dose-response curve was observed, with an inflection point of 9.1 to 18.0 metabolic equivalent value (MET)-hours/week (HR 0.92, 95% CI 0.70 to 1.22 for 0.1 to 9.0 MET-hours/week; HR 0.70, 95% CI 0.53 to 0.93 for 9.1 to 18.0 MET-hours/week).

DISCUSSION

This cross-national analysis suggests that performing 3.1 to 6.0 hours of physical activity and expending 9.1 to 18.0/MET-hours of energy per week may reduce dementia risk.

[Physical activity in the elderly with other major neurocognitive disorders]

For decades, the literature was skeptical about the feasibility of motor rehabilitation and its impact, as well as that of physical activity (PA), in subjects with major neurocognitive disorders (MNCD), including Alzheimer's disease. Now, authors report several benefits of PA, both physical and cognitive, by promoting brain perfusion, neurogenesis and synaptic plasticity, as well as decreasing oxidative stress and inflammation. PA should be recommended in cases of TNCM.

The role of nativity in heterogeneous dementia incidence in a large cohort of three Asian American groups and white older adults in California

INTRODUCTION

Literature shows lower dementia incidence in Asian American groups versus whites, varying by Asian ethnicity. One hypothesized driver is nativity differences (eg, healthy immigrant effect).

METHODS

We followed a cohort of 6243 Chinese, 4879 Filipino, 3256 Japanese, and 141,158 white Kaiser Permanente Northern California members for incident dementia (2002 to 2020), estimating age-adjusted dementia incidence rates by ethnicity and nativity, and hazard ratios (HR) for nativity on dementia incidence using ethnicity-stratified age- and sex-adjusted Cox proportional hazards models.

RESULTS

Dementia incidence appeared higher in foreign- versus US-born Filipinos (HR, 95% confidence interval: 1.39, 1.02 to 1.89); differences were small in Japanese (1.07, 0.88 to 1.30) and Chinese (1.07, 0.92 to 1.24). No nativity differences were observed among whites (1.00, 0.95 to 1.04).

DISCUSSION

Nativity does not explain lower dementia incidence in Asian Americans versus whites, but may contribute to heterogeneity across Asian ethnicities. Future research should explore differential impacts of social and cardiometabolic factors.

Examining the Effect of Increased Aerobic Exercise in Moderately Fit Adults on Psychological State and Cognitive Function

Regular physical exercise can decrease the risk for obesity, diabetes, and cardiovascular disease, increase life expectancy, and promote psychological health and neurocognitive functioning. Cross-sectional studies show that cardiorespiratory fitness level (VO2 max) is associated with enhanced brain health, including improved mood state and heightened cognitive performance. Interventional studies are consistent with these cross-sectional studies, but most have focused on low-fit populations. Few such studies have asked if increasing levels of physical activity in moderately fit people can significantly enhance mood, motivation, and cognition. Therefore, the current study investigated the effects of increasing aerobic exercise in moderately fit individuals on psychological state and cognitive performance. We randomly assigned moderately fit healthy adults, 25-59 years of age, who were engaged in one or two aerobic exercise sessions per week to either maintain their exercise regimen (n = 41) or increase their exercise regimen (i.e., 4-7 aerobic workouts per week; n = 39) for a duration of 3 months. Both before and after the intervention, we assessed aerobic capacity using a modified cardiorespiratory fitness test, and hippocampal functioning via various neuropsychological assessments including a spatial navigation task and the Mnemonic Similarity Task as well as self-reported measures including the Positive and Negative Affect Scale, Beck Anxiety Inventory, State-Trait Anxiety Inventory, Perceived Stress Scale, Rumination Scale, Eating Disorders Examination, Eating Attitudes Test, Body Attitudes Test, and Behavioral Regulation of Exercise Questionnaire. Consistent with our initial working hypotheses, we found that increasing exercise significantly decreased measures of negative affect, including fear, sadness, guilt, and hostility, as well as improved body image. Further, we found that the total number of workouts was significantly associated with improved spatial navigation abilities and body image as well as reduced anxiety, general negative affect, fear, sadness, hostility, rumination, and disordered eating. In addition, increases in fitness levels were significantly associated with improved episodic memory and exercise motivation as well as decreased stress and disordered eating. Our findings are some of the first to indicate that in middle-aged moderately-fit adults, continuing to increase exercise levels in an already ongoing fitness regimen is associated with additional benefits for both psychological and cognitive health.

The Association between Physical Activity and Cognitive Function: Data from the China Health and Nutrition Survey

Background

Decreased cognitive function is a common problem in the old adults, which has high risk of progression to Alzheimer's diseases (AD) and other dementias. This study was aimed at finding out the association between physical activity and cognitive function.

Methods

In total, 1514 participants with the age ≥ 55 years old registered in the China Health and Nutrition Survey (CHNS) database were selected in this study. The association between physical activity and cognitive function was analyzed via the generalized additive model. The association between the variables and the cognitive function score was expressed as β coefficient with 95% confidence intervals (CIs).

Results

After adjusting age, ethnicity, stratum, marital status, education, memory status, and memory changes, the cognitive function score was increased by 0.011 points for every 1-point increase in domestic score (β = 0.011, P = 0.043). Subgroup analysis indicated that in the female group, for every 1-point increase in the domestic score, the cognitive function score increased by 0.019 points (β = 0.019, P = 0.017). In people with good memory status, each 1-point increase in domestic score increased the cognitive function score of 0.020 points (β = 0.020, P = 0.017).

Conclusions

The decreased cognitive function was correlated with decreased domestic physical activity. The increased domestic physical activity was associated with an increased cognitive function in females and people with good memory status. The findings might offer a reference for deep understanding of the association between physical activity and cognitive function.

Physical activity as a protective factor for dementia and Alzheimer's disease: systematic review, meta-analysis and quality assessment of cohort and case-control studies

Objective

Physical activity (PA) is associated with a decreased incidence of dementia, but much of the evidence comes from short follow-ups prone to reverse causation. This meta-analysis investigates the effect of study length on the association.

Design

A systematic review and meta-analysis. Pooled effect sizes, dose–response analysis and funnel plots were used to synthesise the results.

Data sources

CINAHL (last search 19 October 2021), PsycInfo, Scopus, PubMed, Web of Science (21 October 2021) and SPORTDiscus (26 October 2021).

Eligibility criteria

Studies of adults with a prospective follow-up of at least 1 year, a valid cognitive measure or cohort in mid-life at baseline and an estimate of the association between baseline PA and follow-up all-cause dementia, Alzheimer’s disease or vascular dementia were included (n=58).

Results

PA was associated with a decreased risk of all-cause dementia (pooled relative risk 0.80, 95% CI 0.77 to 0.84, n=257 983), Alzheimer’s disease (0.86, 95% CI 0.80 to 0.93, n=128 261) and vascular dementia (0.79, 95% CI 0.66 to 0.95, n=33 870), even in longer follow-ups (≥20 years) for all-cause dementia and Alzheimer’s disease. Neither baseline age, follow-up length nor study quality significantly moderated the associations. Dose–response meta-analyses revealed significant linear, spline and quadratic trends within estimates for all-cause dementia incidence, but only a significant spline trend for Alzheimer’s disease. Funnel plots showed possible publication bias for all-cause dementia and Alzheimer’s disease.

Conclusion

PA was associated with lower incidence of all-cause dementia and Alzheimer’s disease, even in longer follow-ups, supporting PA as a modifiable protective lifestyle factor, even after reducing the effects of reverse causation.

The Effect of Convergence Gamification Training in Community-Dwelling Older People: A Multicenter, Randomized Controlled Trial

OBJECTIVES

It is necessary to improve the health of older adults through exercise, but there is no concrete way to implement it or an environment in which they can exercise continuously. Our objective was to confirm the safety and efficacy of information technology (IT) convergence gamification exercise equipment for older adults. We tried to demonstrate equivalence to conventional exercise by comparing the functional improvement.

DESIGN

Randomized controlled trial, with 8-week-long IT convergence exercises 3 times a week vs conventional exercise.

SETTING AND PARTICIPANTS

40 community-dwelling participants aged 60-85 years.

METHOD

Participants were randomly divided into a conventional exercise group (group 1) and an IT convergence exercise group (group 2). Both groups were trained for 8 weeks, and functional assessment was performed before training (pre-evaluation), after training, and after 4 weeks of rest.

RESULTS

There were functional improvements in both groups. A comparison of the differences in the functional assessment between pre-evaluation and after 8 weeks of training yielded the following results. In group 1, the mean Five Times Sit to Stand Test-30 seconds was scored as 3.60 ± 2.56 (P < .015); Five Times Sit to Stand Test-5 times, -1.75 ± 2.04 s (P < .015); Berg Balance Scale, 1.05 ± 1.39 (P < .015); Timed Up-and-Go test, -0.64 ± 0.64 s (P < .015); and 10-m Walking Test, -0.35 ± 0.47 s (P < .015). And in group 2, the mean Five Times Sit to Stand Test-30 seconds (s) was scored as 3.70 ± 2.62 (P < .015), Five Times Sit to Stand Test-5 times, -1.65 ± 1.59 s (P < .015); Berg Balance Scale, 1.05 ± 1.00 (P < .015); Timed Up-and-Go test, -0.93 ± 0.68 s (P < .015); 10-m Walking Test, -0.41 ± 0.489 s (P < .015); Chair Sit and Reach test, 2.23 ± 3.19 cm (P < .015); and Korean version of the Falls Efficacy Scale-International, -1.05 ± 1.43 (P < .015).

CONCLUSION AND IMPLICATIONS

The results of this study suggest that the IT convergence gamification exercise equipment such as balpro110 has exercise effects similar to conventional exercise and also has advantages as an alternative to exercise for older adults in the next generation.

Association Between Physical Activity and Risk of Disabling Dementia in Japan

Importance

The associations of daily total physical activity and total moderate to vigorous physical activity (MVPA) with dementia are still unclear.

Objective

To investigate the association between daily total physical activity and subsequent risk of disabling dementia in large-scale, extended follow-up prospective study.

Design, Setting, and Participants

This prospective cohort study used data from questionnaires collected between 2000 and 2003 from 8 areas from the Japan Public Health Center-based Prospective Disabling Dementia Study. Participants included adults aged 50 to 79 years in with available follow-up data on disabling dementia. Data analysis was performed from February 1, 2019, to July 31, 2021.

Exposures

Daily total physical activity, total MVPA, and leisure-time MVPA.

Main Outcomes and Measures

The main outcome was incidence of disabling dementia during the dementia ascertainment period between 2006 and 2016, based on the national long-term care insurance system. Risks of dementia in association with daily total physical activity, total MVPA, and leisure time MVPA were calculated using multivariable adjusted hazard ratios (aHRs).

Results

Among 43 896 participants (mean [SD] age, 61.0 [7.5] years; 23 659 [53.9%] women), 5010 participants were newly diagnosed with disabling dementia during a mean (SD) of 9.5 (2.8) years in the dementia ascertainment period. In the highest daily total physical activity group, compared with the lowest activity group, risk of dementia was lower in men (aHR, 0.75 [95% CI, 0.66-0.85]; P for trend < .001) and women (aHR, 0.75 [95% CI, 0.67-0.84]; P for trend < .001). Similar inverse associations were observed in men and women for total MVPA (men: aHR, 0.74 [95% CI, 0.65-0.84]; P for trend < .001; women: aHR, 0.74 [95% CI, 0.66-0.83]; P for trend < .001) and leisure-time MVPA (men: aHR, 0.59 [95% CI, 0.53-0.67]; P for trend < .001; women: aHR, 0.70 [95% CI, 0.63-0.78]; P for trend < .001). However, these inverse associations disappeared when participants diagnosed with disabling dementia within 7 years of the starting point were excluded in men (aHR, 0.93 [95%CI, 0.77-1.12]) and within 8 years were excluded in women (aHR, 0.86 [95%CI, 0.71-1.04]). The association remained significant among men in the highest vs lowest group of leisure-time MVPA, after excluding participants diagnosed within the first 9 years (aHR, 0.72 [95% CI, 0.56-0.92]; P for trend = .004).

Conclusions and Relevance

This cohort study examined associations of daily total physical activity and total MVPA with risk of disabling dementia. The findings suggest that a high level of leisure-time MVPA was associated with decreased risk of disabling dementia in men.

Effect of physical activity on cognitive domains in dementia and mild cognitive impairment: overview of systematic reviews and meta-analyses

OBJECTIVE

To assess the effect of physical activity on cognitive domains in persons with dementia or mild cognitive impairment.

DESIGN

An overview of systematic reviews and meta-analyses of randomized controlled trials were performed.

METHODS

A literature search was performed in PubMed, Scopus, and Cochrane Database of Systematic Reviews databases up to February 2020. Data about the change in cognitive domains after physical activity intervention was extracted and plotted.

RESULTS

We included 11 meta-analyses in this overview. The most frequent type of physical activity for the intervention group was the aerobic exercise with a duration between 6 and 78 weeks. Global cognition was the most common form of assessing the cognitive function, follow of executive function, delayed recall, attention, and verbal fluency. We found a positive effect of physical activity on global cognition, executive function, and delayed recall, but no effect on verbal fluency, attention, and immediate recall.

CONCLUSION

Physical activity shows a positive effect on cognition in people with dementia and mild cognitive impairment, especially when it was assessed as global cognition. Positive effects on executive function and memory were also shown. This result confirms the relevance of physical activity in the treatment of persons with cognitive impairment.

Efficacy of an Integrated Training Device in Improving Muscle Strength, Balance, and Cognitive Ability in Older Adults

OBJECTIVE

To determine the effects of an integrated training device for strength and balance on extremity muscle strength, postural balance, and cognition in older adults using a combination with various rehabilitation training games, in which balance, strength, and cognitive training were configured in a single device.

METHODS

This prospective study included 20 healthy participants aged 65-85 years. Participants trained for 30 minutes daily, 3 days weekly, for 6 weeks with an integrated training device for strength and balance (SBT-120; Man&Tel Inc., Gumi, Korea). Main outcomes were measured using the Korean Mini-Mental State Examination (K-MMSE), Korean version of the Montreal Cognitive Assessment (K-MoCA), Timed Up and Go Test (TUG), Functional Reach Test (FRT), Berg Balance Scale (BBS), and Manual Muscle Test. Measurements were taken at three time points: T0 (pretreatment), T1 (immediately after treatment), and T2 (4 weeks after treatment).

RESULTS

All 20 patients completed the training, and TUG, FRT, and BBS scores significantly improved at T1 and T2 compared to T0. Mean TUG scores decreased by 0.99±2.00 at T1 and 1.05±1.55 at T2 compared to T0. Mean FRT scores increased by 6.13±4.26 at T1 and 6.75±4.79 at T2 compared to T0. BBS scores increased by 0.60±0.94 at T1 and 0.45±1.15 at T2 compared to T0. Moreover, muscle strength and cognition (K-MMSE and K-MoCA scores) increased after training.

CONCLUSION

Our findings suggest that an integrated training device for strength and balance can be a safe and useful tool for older adults.

Forgot to Exercise? Exercise Derived Circulating Myokines in Alzheimer's Disease: A Perspective

Regular exercise plays an essential role in maintaining healthy neurocognitive function and central nervous system (CNS) immuno-metabolism in the aging CNS. Physical activity decreases the risk of developing Alzheimer's Disease (AD), is associated with better AD prognosis, and positively affects cognitive function in AD patients. Skeletal muscle is an important secretory organ, communicating proteotoxic and metabolic stress to distant tissues, including the CNS, through the secretion of bioactive molecules collectively known as myokines. Skeletal muscle undergoes significant physical and metabolic remodeling during exercise, including alterations in myokine expression profiles. This suggests that changes in myokine and myometabolite secretion may underlie the well-documented benefits of exercise in AD. However, to date, very few studies have focused on specific alterations in skeletal muscle-originating secreted factors and their potential neuroprotective effects in AD. In this review, we discuss exercise therapy for AD prevention and intervention, and propose the use of circulating myokines as novel therapeutic tools for modifying AD progression.

Microglia and modifiable life factors: Potential contributions to cognitive resilience in aging

Given the increasing prevalence of age-related cognitive decline, it is relevant to consider the factors and mechanisms that might facilitate an individual's resiliency to such deficits. Growing evidence suggests a preeminent role of microglia, the prime mediator of innate immunity within the central nervous system. Human and animal investigations suggest aberrant microglial functioning and neuroinflammation are not only characteristic of the aged brain, but also might contribute to age-related dementia and Alzheimer's Disease. Conversely, accumulating data suggest that modifiable lifestyle factors (MLFs), such as healthy diet, exercise and cognitive engagement, can reliably afford cognitive benefits by potentially suppressing inflammation in the aging brain. The present review highlights recent advances in our understanding of the role for microglia in maintaining brain homeostasis and cognitive functioning in aging. Moreover, we propose an integrated, mechanistic model that postulates an individual's resiliency to cognitive decline afforded by MLFs might be mediated by the mitigation of aberrant microglia activation in aging, and subsequent suppression of neuroinflammation.

Paradoxical association between atrial fibrillation/flutter and high cholesterol over age 75 years: The Kuakini Honolulu Heart Program and Honolulu-Asia Aging Study

INTRODUCTION

Several studies have indicated high cholesterol is paradoxically associated with low prevalence of atrial fibrillation/flutter (AF). However, the etiology is uncertain. One potential explanation might be the confounding effect of age exemplifying prevalence-incidence (Neyman's) bias. However, this bias has not often been discussed in depth in the literature. Therefore, we conducted a cross-sectional analysis to test the hypothesis that there is a paradoxical association between lipid profile and AF prevalence.

METHODS

This is a cross-sectional study design, using data from the Kuakini Honolulu Heart Program. Participants were 3741 Japanese-American men between 71 and 93 years old living in Hawaii. Serum total cholesterol (TC) level was measured and categorized into quartiles. AF was diagnosed by 12‑lead Electrocardiogram. We categorized age into quartiles (71-74, 75-77, 78-80 and 81+ years).

RESULTS

We observed opposite associations between AF and TC among different age groups. For participants age ≥75, higher TC levels were paradoxically associated with lower prevalence of AF after multivariable adjustment, i.e. the odds ratios of AF comparing the highest TC quartile with the lowest TC quartile for age 75-77, 78-80 and 81+ years were 0.17 (95% confidence interval [CI], 0.06-0.52), 0.28 (95% CI, 0.07-1.09) and 0.14 (95% CI, 0.03-0.62), respectively. Conversely, for those who were 71-74 years old, the odds ratio of AF was 2.09 (95% CI, 0.76-5.75) between the highest and the lowest TC quartiles.

CONCLUSIONS

There is a paradoxical association of TC with AF in Japanese-American men age ≥75, but not <75 years. The paradox might be explained by Neyman's bias.

Does APOE genotype moderate the relationship between physical activity, brain health and dementia risk? A systematic review

INTRODUCTION

For decades, researchers have tried to understand the moderating effect of APOE ε4 carriage on the relationship between physical activity (PA), brain health and dementia risk. However, this field has produced inconsistent findings.

METHOD

We conducted a systematic review of the literature, searching for observational and interventional studies examining the effect of APOE ε4 carriage on the relationships between PA, dementia risk and different markers of brain health.

RESULTS

Observational studies using dementia risk as a primary outcome measure generally found that in shorter follow-up periods (up to 10 years) both APOE ε4 carriers and non-carriers benefit from PA, although longer follow-ups showed mixed results. In neuroimaging studies, mainly carriers or both groups showed benefits. Additionally, the association between PA and amyloid burden was more evident among carriers. Overall, studies with greater samples of active APOE ε4 carriers are more likely to report benefits within this group in terms of lower dementia risk and reduced brain pathology.

DISCUSSION

Although we have identified some patterns for the modulating effect of APOE ε4 on PA and dementia or brain pathology, the available data is, overall, inconclusive. Heterogeneity in study design, methodology, and outcomes blur the ability to detect clear associations.

Prevention and Treatment of Alzheimer's Disease: Biological Mechanisms of Exercise

Alzheimer's disease (AD) is the most common form of dementia. With an aging population and no disease modifying treatments available, AD is quickly becoming a global pandemic. A substantial body of research indicates that lifestyle behaviors contribute to the development of AD, and that it may be worthwhile to approach AD like other chronic diseases such as cardiovascular disease, in which prevention is paramount. Exercise is an important lifestyle behavior that may influence the course and pathology of AD, but the biological mechanisms underpinning these effects remain unclear. This review focuses on how exercise can modify four possible mechanisms which are involved with the pathology of AD: oxidative stress, inflammation, peripheral organ and metabolic health, and direct interaction with AD pathology. Exercise is just one of many lifestyle behaviors that may assist in preventing AD, but understanding the systemic and neurobiological mechanisms by which exercise affects AD could help guide the development of novel pharmaceutical agents and non-pharmacological personalized lifestyle interventions for at-risk populations.

Cognitive effects of video games in older adults and their moderators: a systematic review with meta-analysis and meta-regression

The growing interest in preserving cognition through video games in the ageing population is evidenced by its wealth of literature. However, there has been a lack of consensus on video games efficacy and even limited understanding on the factors moderating its effectiveness. The present review sought to evaluate video game effects, relative to no-game control condition, on cognitive functions in older adults. The functions included processing speed, attention, delayed memory, reasoning, and executive functions (inhibition, shifting and updating memory). Personal and methodological moderators were explored to explain the variability in cognitive effects using meta-regression. Through a systematic literature search of online databases, 27 intervention studies were eligible, with a total of 1126 participants, for analysis. Using random-effect models, small but significant training effects were found on updating memory but none were detected in other cognitive functions. The heterogeneity across studies was in general high for all cognitive functions and was partially accounted for, in all cognitive functions except for inhibition and updating, by different moderators such as the proportion of females, outcome measure parameters, training intensity, and game type. The findings highlight limited effects of video games on cognitive functions that were largely influenced by factors related to study design.

Exercise Training Results in Lower Amyloid Plaque Load and Greater Cognitive Function in an Intensity Dependent Manner in the Tg2576 Mouse Model of Alzheimer's Disease

Three months of exercise training (ET) decreases soluble Aβ₄₀ and Aβ₄₂ levels in an intensity dependent manner early in life in Tg2576 mice (Moore et al., 2016). Here, we examined the effects of 12 months of low- and high- intensity exercise training on cognitive function and amyloid plaque load in the cortex and hippocampus of 15-month-old Tg2576 mice. Low- (LOW) and high- (HI) intensity ET animals ran at speeds of 15 m/min on a level treadmill and 32 m/min at a 10% grade, respectively, for 60 min/day, five days/week, from 3 to 15 months of age. Sedentary mice (SED) were placed on a level, non-moving, treadmill for the same duration. ET mice demonstrated a significantly lower amyloid plaque load in the cortex and hippocampus that was intensity dependent. Improvement in cognitive function, assessed by Morris Water Maze and Novel Object Recognition tests, was greater in the HI group compared to the LOW and SED groups. LOW mice performed better in the initial latency to the platform location during the probe trial of the Morris Water Maze (MWM) test than SED, but not in any other aspect of MWM or the Novel Object Recognition test. The results of this study indicate that exercise training decreases amyloid plaque load in an intensity dependent manner and that high-intensity exercise training improves cognitive function relative to SED mice, but the intensity of the LOW group was below the threshold to demonstrate robust improvement in cognitive function in Tg2576 mice.

Alzheimer's Disease and its Related Dementias among Asian Americans, Native Hawaiians, and Pacific Islanders: A Scoping Review

BACKGROUND

The Asian American, Native Hawaiian, and Pacific Islander (AANHPI) aging population is rapidly growing and the burden of Alzheimer's disease and its related dementias (ADRD) will likely mirror this demographic growth. AANHPIs face significant barriers in obtaining timely ADRD diagnosis and services; yet little is known about ADRD in this population.

OBJECTIVE

The study objective is to conduct a systematic review on the published literature on ADRD among AANHPIs to identify gaps and priorities to inform future research and action plans.

METHODS

The systematic review was conducted following the PRISMA Protocol for Systematic Reviews. Co-author (TR), an experienced Medical Librarian, searched PubMed, EMBASE, PsycINFO, Cochrane Central of Clinical Trials, Ageline, and Web of Science for peer-reviewed articles describing ADRD among AANHPIs. The search was not limited by language or publication date. Each citation was reviewed by two trained independent reviewers. Conflicts were resolved through consensus.

RESULTS

The title/abstract and full texts of 1,447 unique articles were screened for inclusion, yielding 168 articles for analysis. Major research topics included prevalence, risk factors, comorbidities, interventions and outreach, knowledge and attitudes, caregiving, and detection tools. A limited number of studies reported on national data, on NHPI communities generally, and on efficacy of interventions targeting AANHPI communities.

CONCLUSION

To our knowledge, this is the first systematic review on ADRD among AANHPI populations. Our review provides a first step in mapping the extant literature on ADRD among this underserved and under-researched population and will serve as a guide for future research, policy, and intervention.

Current and past leisure time physical activity in relation to risk of Alzheimer's disease in older adults

INTRODUCTION

The associations between self-reported current and past leisure time physical activity (LTPA) and Alzheimer's disease (AD) incidence were determined using data from the multiethnic Washington/Hamilton Heights-Inwood Columbia Aging Project (WHICAP) study.

METHODS

The metabolic equivalent of LTPA energy expenditure was calculated for self-reported current and past LTPA for 1345 older adults. A Cox proportional hazard model was conducted to estimate the association between LTPA (low, middle, and high) and incident AD risk.

RESULTS

Comparing high to low level, current and past LTPA were both associated with reduced AD risk, with hazard ratio (95% confidence interval) = 0.39 (0.20-0.75) and 0.37 (0.18-0.75), respectively. Compared with "always low," "increased" and "always high" LTPA throughout life were associated with reduced AD risk, with hazard ratio (95% confidence interval) = 0.60 (0.36-0.99) and 0.28 (0.08-0.94), respectively. Light- and moderate-intensity LTPA were associated with lower AD risk.

DISCUSSION

LTPA both throughout life and later in life are associated with lower risk of AD.

Episodic memory boosting in older adults: exploring the association of encoding strategies and physical activity

Background: Contextual memory is susceptible to the effects of aging and its impairment compromises episodic memories and quality of life in older adults. Objective: Compare the effects of cognitive support on incidental contextual memory free recall and recognition with a naturalistic experimental paradigm and explore the association of encoding strategies and physical activity on memory improvement. Methods: Subjects (≥60 years, n = 52) were assigned to one of two encoding conditions for the contextual memory task: with or without an incidental associative instruction to encourage association of an item to its spatial context. Immediate free recall and recognition tests were run to assess the encoding instruction efficiency. The association of memory performance and physical activity was analyzed using the scores on the International Physical Activity Questionnaire (IPAQ) to subdivide each experimental group into Low IPAQ (below median) and High IPAQ (above median) subgroups. Results: The associative encoding instruction increased contextual memory free recall and recognition, with greater effects on free recall. The most robust associations between physical activity and contextual memory were also seen on free recall, in which higher levels of physical activity corresponded to increased baseline performance (non-associative encoding condition) and greater improvement of memory by the encoding support (associative encoding condition). Conclusion: Cognitive support at encoding can improve contextual memory free recall and recognition, suggesting they are prone to rehabilitation. Moreover, higher physical activity levels were positively associated with encoding strategies on contextual memory improvement, increasing the availability of latent process-based components of the cognitive reserve.

Social Determinants of Racial Disparities in Cognitive Functioning in Later Life in Canada

Objective: The objectives of this study were (a) to assess the nature and extent of racial disparities in cognitive functioning among older adults in Canada, and (b) to assess the role of socioeconomic factors and patterned health behaviors as social determinants of racial disparities in cognitive functioning. Method: Data were drawn from the 2009-2010 Canadian Community Health Survey. The study sample included 20,646 people aged 60 years or older. Ordered logistic regression analyses were carried out to test hypotheses linking race, socioeconomic factors, and patterned health behaviors, and cognitive functioning. Results: Our findings revealed a racial gap in cognitive functioning among older adults in Canada. This gap was, in part, mediated by socioeconomic inequalities (in income and food security) and socially patterned behaviors (i.e., drinking, physical activity levels). However, socioeconomic status (SES) and behavioral factors appeared to operate independently of one another. Discussion: The findings suggest a need to focus on the direct effects of race as well as its indirect effects, through socioeconomic factors and patterned health behaviors, for an understanding of racial disparities in cognitive functioning.

Lifespan Intellectual Factors, Genetic Susceptibility, and Cognitive Phenotypes in Aging: Implications for Interventions

Along with rapid global population aging, the age-related cognitive disorders such as mild cognitive impairment (MCI) and dementia have posed a serious threat to public health, health care system, and sustainable economic and societal development of all countries. In this narrative review, we seek to summarize the major epidemiological studies from the life-course perspective that investigate the influence of genetic susceptibility [e.g., apolipoprotein (APOE) ε4 allele] and intellectual or psychosocial factors (e.g., educational attainments and leisure activities) as well as their interactions on cognitive phenotypes in aging. Numerous population-based studies have suggested that early-life educational attainments and socioeconomic status, midlife work complexity and social engagements, late-life leisure activities (social, physical, and mentally-stimulating activities), certain personality traits (e.g., high neuroticism and low conscientiousness), and depression significantly affect late-life cognitive phenotypes. Furthermore, certain intellectual or psychosocial factors (e.g., leisure activities and depression) may interact with genetic susceptibility (e.g., APOE ε4 allele) to affect the phenotypes of cognitive aging such that risk or beneficial effects of these factors on cognitive function may vary by carrying the susceptibility genes. Current evidence from the randomized controlled trials that support the cognitive benefits of cognitive training among cognitive healthy older adults remains limited. The cognitive reserve hypothesis has been proposed to partly explain the beneficial effects of lifetime intellectual and psychosocial factors on late-life cognitive function. This implies that, from a life-course perspective, preventive intervention strategies targeting multiple modifiable intellectual and psychosocial factors could interfere with clinical expression of cognitive disorders in old age and delay the onset of dementia syndrome, and thus, may help achieve healthy brain aging.

Impact of time spent walking on incident dementia in elderly Japanese

OBJECTIVES

This study examined the hypothesis that time spent walking daily has a marked impact on incident dementia.

METHODS/DESIGN

First, we analyzed data from a Japanese cohort (n = 13 990 aged ≥65 y) to obtain hazard ratios. Time spent walking per day (<0.5, 0.5-1, or ≥1 h) was assessed using a self-reported questionnaire. Data on 5.7-year incident dementia were retrieved from the public long-term care insurance database. After estimating the multivariate-adjusted hazard ratios (HRs) of incident dementia using the Cox model, the population attributable fraction (PAF) was calculated using the prevalence in a representative Japanese survey, the "National Health and Nutrition Survey".

RESULTS

The time spent walking per day showed an inverse association with incident dementia: the multiple-adjusted HRs (95% confidence intervals) were 1.00 (reference) for less than 0.5 hour, 0.81 [0.71, 0.92] for 0.5 to 1 hour, and 0.72 [0.62, 0.84] for more than or equal to 1 hour. Our estimates indicate that 18.1% of dementia cases would be attributable to walking if all subjects walked more than or equal to 1 h/d and 14.0% if subjects increased their daily time spent walking to one level above the present one (<0.5 to 0.5-1 or 0.5-1 to ≥1 h).

CONCLUSIONS

Our results suggest that the daily time spent walking has a considerable preventive impact on incident dementia in Japan.

The CAIDE Dementia Risk Score and the Honolulu-Asia Aging Study

INTRODUCTION

The CAIDE (Cardiovascular Risk Factors, Aging, and Incidence of Dementia) dementia risk score is based on demographic, genetic, and modifiable risk factors in midlife and has been shown to be predictive of later-life dementia.

OBJECTIVE

To test the predictive capacity of the CAIDE dementia risk score among a cohort of Japanese-American men.

METHODS

Midlife measures were obtained from a sample of 3,582 Japanese-American men in the Honolulu Heart Program (1965-1968, average age = 53.1 years). A follow-up exam in 1991 (average age = 77.8 years) assessed cognitive impairment using the Cognitive Abilities Screening Instrument (CASI). Severe cognitive impairment was defined as a CASI score <60.

RESULTS

In this cohort, the CAIDE dementia risk score demonstrates significant association with later-life severe cognitive impairment (OR = 1.477, 95% CI: 1.39-1.58). However, the area under the receiver-operating characteristic curve c-statistics suggests poor predictive ability (c = 0.645, 95% CI: 0.62-0.67). Using a score cut-point of 10, the accuracy is acceptable (0.82), but the sensitivity is low (0.50).

CONCLUSION

While the CAIDE dementia risk score at midlife is associated with later development of cognitive impairment in Japanese-American men, its predictive capacity in this population is weak.

Social support, physical activity and psychological distress among community-dwelling older Ghanaians

OBJECTIVE

Physical activity (PA) has often been linked with improved mental health outcomes among older people but the subject has received limited attention in sub-Saharan African context. This paper examines the moderating effect of social support (SS) on the association between PA and psychological distress (PD) among community-dwelling older persons in Ghana.

METHODS

Individuals 50 years or older (N = 1200) who participated in a 2016/2017 Aging, Health, Psychological Wellbeing and Health-seeking Behavior Study (AHPWHB) were included. PD outcome, measured by the Kessler Psychological Distress Scale (KPDS-K10) was regressed on PA levels, SS and the interaction term.

RESULTS

Findings suggest that regular PA (OR = 0.824; 95%CI: 0.610-0.913) and higher levels of SS (OR = 0.475; 95%CI: 0.360-0.626) were associated with reduced PD outcomes after adjusting for theoretically relevant confounding variables. More importantly, the inclusion of the interaction term (PA × SS) showed a significant negative relationship of regular PA with the PD outcome as SS levels increased (OR = 0.651; 95%CI: 0.376-0.727).

CONCLUSIONS

Although regular PA potentially contributes to reducing PD among older persons, the relationship is even stronger for those embedded in a higher constellation of SS. Policy and practical interventions seeking to improve regular PA engagement such as old-age friendly environment and psychological resources for socially isolated older persons are warranted.

The Mental Activity and eXercise (MAX) trial: Effects on physical function and quality of life among older adults with cognitive complaints

BACKGROUND

Older adults with cognitive complaints are vulnerable to dementia, physical impairments, and poor quality of life. Exercise and mental activity may improve physical function and health-related quality of life (HRQOL) but combinations have not been investigated systematically. The Mental Activity and eXercise (MAX) trial found that mental activity plus exercise over 12weeks improved cognitive function (primary outcome) in sedentary older adults with cognitive complaints.

OBJECTIVE

To investigate the effects of combinations of two mental activity and exercise programs on physical function and HRQOL (secondary outcomes).

METHODS

Participants (n=126, age 73±6years, 65% women) were randomized to 12weeks of exercise (aerobic exercise or stretching/toning, 3×60min/week) plus mental activity (computer-based cognitive training or educational DVDs, 3×60min/week) using a factorial design. Assessments included the Senior Fitness Test (physical function), Short Form-12 physical and mental sub-scales (HRQOL), and CHAMPS questionnaire (physical activity).

RESULTS

There were no differences between groups at baseline (p>0.05). We observed improvements over time in most physical function measures [chair stands (p-for-time=0.001), arm curls (p-for-time<0.001), step test (p-for-time=0.003), sit & reach (p-for-time=0.01), and back scratch (p-for-time=0.04)] and in physical HRQOL (p-for-time=0.04). There were no differences in change between groups (group∗time p>0.05). Changes in most physical function measures and physical HRQOL correlated with physical activity changes.

CONCLUSION

Combined mental activity and exercise interventions of various types can improve both physical function and physical HRQOL among sedentary older adults with cognitive complaints. Exercise control group design should be carefully considered as even light exercise may induce benefits in vulnerable older adults.

Cognitive Dysfunction in Urban-Community Dwelling Prefrail Older Subjects

OBJECTIVES

A number of studies have reported that frailty is cross-sectionally associated with cognitive decline and is also a risk for future cognitive decline or dementia; however, there have been only a few studies that focus on the association between prefrailty and cognitive dysfunction. In the current study, we investigated the association between prefrailty and cognition.

DESIGN

A cross-sectional study of the data obtained at registration in a randomized control trial.

SETTING

Toyota, Japan.

PARTICIPANTS

Community-dwelling older subjects (male 54.6%) who had cognitive complaints.

MEASUREMENTS

A battery of neuropsychological and physical assessments were performed. Prefrailty was defined as exhibiting one or two of the five Fried criteria (weight loss, exhaustion, weakness, slow gait speed and low physical activity). We performed a multiple regression analysis to investigate the associations of cognitive performance with prefrailty, adjusting for the factors that were significantly different between the robust and prefrailty groups. To assess the cognitive attributes that were significantly associated with prefrailty, logistic analysis was performed to see if one specific criterion of the five frailty criteria was associated with cognitive performance.

RESULTS

The study subjects included 183 prefrail and 264 robust individuals. The prefrail subjects with cognitive complaints were older, less educated, more depressive, and more likely to have diabetes mellitus than the robust subjects. The prefrail subjects had lower performance in a wide-range of cognitive domains, and after adjustments for age, education, depressive mood, and diabetes mellitus, prefrailty was associated with a decline in delayed memory and processing speed. Among the components of the Fried criteria, slow gait speed and loss of activity were significantly associated with slow processing speed as assessed by the digit symbol substitution test.

CONCLUSION

The current results demonstrated that prefrailty was associated with worse memory and processing speed performance, but not with other cognitive domains.

The role of exercise in mitigating subcortical ischemic vascular cognitive impairment

Subcortical ischemic vascular cognitive impairment (SIVCI) is the most preventable form of cognitive dysfunction. There is converging evidence from animal and human studies that indicate vascular injury as the primary cause of SIVCI. Currently, there are no curative pharmaceutical treatments for vascular dementia; however, exercise may be a promising strategy to combat SIVCI. This review will focus on the role of exercise as a strategy to prevent or slow the progression of SIVCI, with particular emphasis on the mechanisms by which exercise may improve cerebrovascular function. We propose that exercise may be an effective strategy to combat SIVCI by improving cognitive function, increasing the bioavailability of neurotrophins, stimulating endothelial function, and controlling vascular risk factors. This article is part of the Special Issue "Vascular Dementia".

Physical Activity and Alzheimer's Disease: A Systematic Review

The current literature includes several studies investigating the association between physical activity and risk of Alzheimer's disease (AD). The aim of this review was to systematically evaluate available evidence on this association. Medline via PubMed and CINAHL databases were searched for original English language research articles assessing the relationship between physical activity and incident AD. The review was limited to prospective observational and intervention studies. Criteria for exclusion were studies focusing on individuals with dementia, cross-sectional study design, and case reports. The quality of included studies was assessed in 5 domains of bias. Twenty-four studies met the inclusion criteria. The number of participants ranged from 176 to 5,698. Follow-up time varied from 1 to 34 years. Physical activity was inversely associated with risk of AD in most studies (n = 18). Leisure-time physical activity was particularly protective against AD, but not work-related physical activity. The risk of bias assessment showed that overall quality of evidence was moderate for 16 and low for 8 studies. Beyond all the available general recommendations for health promotion, current evidence does not allow to draw specific practical recommendations concerning the types, frequency, intensity, or duration of physical activity that may be protective against AD.

Physical activity domains and cognitive function over three years in older adults with subjective memory complaints: Secondary analysis from the MAPT trial

OBJECTIVES

We aimed to examine the associations of physical activity (PA) domains (i.e., PA in leisure-time (LTPA), for housework (HPA), or for gardening (GPA)) with cognitive function in older adults with subjective memory complaints (no-dementia) and to investigate if those associations were dependent on the status of apolipoprotein E allele 4 (APOE4), omega-3 levels and mild cognitive impairment (MCI).

DESIGN

Observational prospective secondary analysis using longitudinal data from a randomized controlled trial.

METHODS

Participants were 420 French community-dwelling people (aged 75.6±4.4; 66.4% women) randomized into the placebo group. They were assessed at baseline, 6-, 12-, 24- and 36-month using a battery of neuropsychological tests; a composite cognitive Z score was elaborated for all time points. Data on PA come from baseline and was obtained using a self-reported questionnaire.

RESULTS

In time-adjusted analysis, LTPA significantly predicted cognitive function over three years for almost all tests and the composite Z score, with higher LTPA associated with better function; multivariate analysis showed a significant association only for verbal fluency. HPA was not associated to cognitive function, whereas GPA had mixed results. The magnitude of the PA-cognition associations was very weak, being the strongest for LTPA. Stratified analyses showed that the associations between PA and cognitive function were stronger for MCI, people with normal omega-3 index levels, and APOE4 non-carriers.

CONCLUSIONS

PA domain is an important aspect to take into account when examining the associations between PA and cognitive function. Biomarkers of cognitive function may modulate the PA-cognition associations.

Temporal Relationship Between Cognitive and Physical Performance in Middle-Aged to Oldest Old People

Background

Cognitive and physical impairment frequently co-occur in older people. The aim of this study was to assess the temporal order of these age-related changes in cognitive and physical performance and to assess whether a relationship was different across specific cognitive and physical domains and age groups.

Methods

Cognitive domains included global, executive, and memory function; physical domains included gait speed and handgrip strength. These domains were assessed in two population-based longitudinal cohorts covering the age ranges of 55-64, 65-74, 75-85, and 85-90 years with a follow-up of 5-12 years. Cross-lagged panel models were applied to assess the temporal relationships between the different cognitive and physical domains adjusting for age, sex, education, comorbidity, depressive symptoms, and physical activity.

Results

Over all age groups, poorer executive function was associated with a steeper decline in gait speed (p < .05). From the age of 85 years, this relationship was found across all cognitive and physical domains (p < .02). From the age of 65 years, slower gait speed and/or weaker handgrip strength were associated with steeper declines in global cognitive function (p < .02), with statistically significant results across all cognitive domains in the age group of 75-85 years (p < .04).

Conclusions

The temporal relationship between cognitive and physical performance differs across domains and age, suggesting a specific rather than a general relationship. This emphasizes the importance of repeated measurements on different domains and encourages future research to the development of domain- and age-specific interventions.

Impact of Physical Activity on Cognitive Decline, Dementia, and Its Subtypes: Meta-Analysis of Prospective Studies

The association of physical activity with dementia and its subtypes has remained controversial in the literature and has continued to be a subject of debate among researchers. A systematic review and meta-analysis of longitudinal studies on the relationship between physical activity and the risk of cognitive decline, all-cause dementia, Alzheimer's disease, and vascular dementia among nondemented subjects are considered. A comprehensive literature search in all available databases was conducted up until April 2016. Well-defined inclusion and exclusion criteria were developed with focus on prospective studies ≥ 12 months. The overall sample from all studies is 117410 with the highest follow-up of 28 years. The analyses are performed with both Bayesian parametric and nonparametric models. Our analysis reveals a protective effect for high physical activity on all-cause dementia, odds ratio of 0.79, 95% CI (0.69, 0.88), a higher and better protective effect for Alzheimer's disease, odds ratio of 0.62, 95% CI (0.49, 0.75), cognitive decline odds ratio of 0.67, 95% CI (0.55, 0.78), and a nonprotective effect for vascular dementia of 0.92, 95% CI (0.62, 1.30). Our findings suggest that physical activity is more protective against Alzheimer's disease than it is for all-cause dementia, vascular dementia, and cognitive decline.

Gait Performance Trajectories and Incident Disabling Dementia Among Community-Dwelling Older Japanese

OBJECTIVES

Initial gait speed is a good predictor of dementia in later life. This prospective study used repeated measures analysis to identify potential gait performance trajectory patterns and to determine whether gait performance trajectory patterns were associated with incident disabling dementia among community-dwelling older Japanese.

DESIGN

A prospective, observational, population-based follow-up study.

SETTING

Japan, 2002 to 2014.

PARTICIPANTS

A total of 1686 adults without dementia (mean [SD] age, 71.2 [5.6] years; women, 56.3%) aged 65 to 90 years participated in annual geriatric health assessments during the period from June 2002 through July 2014. The average number of follow-up assessments was 3.9, and the total number of observations was 6509.

MEASUREMENTS

Gait performance was assessed by measuring gait speed and step length at usual and maximum paces. A review of municipal databases in the Japanese public long-term care insurance system revealed that 196 (11.6%) participants developed disabling dementia through December 2014.

RESULTS

We identified 3 distinct trajectory patterns (high, middle, and low) in gait speed and step length at usual and maximum paces in adults aged 65 to 90 years; these trajectory patterns showed parallel declines among men and women. After adjusting for important confounders, participants in the low trajectory groups for gait speed and step length at usual pace were 3.46 (95% confidence interval 1.88-6.40) and 2.12 (1.29-3.49) times as likely to develop incident disabling dementia, respectively, as those in the high trajectory group. The respective values for low trajectories of gait speed and step length at maximum pace were 2.05 (1.02-4.14) and 2.80 (1.48-5.28), respectively.

CONCLUSIONS

Regardless of baseline level, the 3 major trajectory patterns for gait speed and step length tended to show similar age-related changes in men and women in later life. Individuals with low trajectories for gait speed and step length had a higher dementia risk, which highlights the importance of interventions for improvements in gait performance, even among older adults with low gait performance.

Physical Activity and Cognitive Function in Middle-Aged and Older Adults: An Analysis of 104,909 People From 20 Countries

OBJECTIVE

To examine the associations of physical activity (PA) frequency (both moderate and vigorous intensity) and PA levels with cognitive function.

PATIENTS AND METHODS

Data of individuals 50 years or older, from 20 European countries (along with Israel), were collected from 2004 to November 2013 in the biannual Survey of Health, Ageing and Retirement in Europe. A total of 104,909 participants were assessed for cognitive function at least once (mean follow-up length, 29.5±35.7 months). Baseline moderate- and vigorous-intensity PA were reported by participants as more than once a week, once a week, one to three times a month, or hardly ever or never. With regard to PA frequency, participants were categorized as inactive, low active, intermediate active, or high active. The main outcome measure is a cognitive composite score created by summing the z scores of 4-item temporal orientation, 10-word list for delayed recall, and verbal fluency.

RESULTS

Adjusted, 2-level mixed-effect regressions found that compared with doing no PA, doing PA more than once a week, once a week, or one to three times a month was positively associated with the composite score (β coefficients varied from 0.52 to 0.75 for moderate-intensity PA and from 0.26 to 0.33 for vigorous-intensity PA). Similarly, compared with the inactive category, high-active, intermediate-active, and low-active categories had positive associations with the composite score (β varied from 0.77 to 1.10). Positive associations were also obtained between PA variables and the raw scores of cognitive tests.

CONCLUSION

Physical activity has dose-response associations with cognitive function, with even low PA frequencies (few times per month) being positively associated with cognitive function during aging.

Lifestyle Factors and Dementia in the Oldest-old: The 90+ Study

Dementia incidence increases exponentially with age even in people aged 90 years and above. Because therapeutic regimens are limited, modification of lifestyle behaviors may offer the best means for disease control. To test the hypotheses that lifestyle factors are related to lower risk of dementia in the oldest-old, we analyzed data from The 90+ Study, a population-based longitudinal cohort study initiated in 2003. This analysis included 587 participants (mean age=93 y) seen in-person and determined not to have dementia at enrollment. Information on lifestyle factors (smoking, alcohol, caffeine, vitamin supplements, exercise, and other activities) was obtained at enrollment and was available from data collected 20 years previously. After an average follow-up of 36 months, 268 participants were identified with incident dementia. No variable measured 20 years previously was associated with risk. Engagement in specific social/mental activities and intakes of antioxidant vitamin supplements and caffeine at time of enrollment were, associated with significantly reduced risks. When these variables were analyzed together, the HRs changed little and remained significant for reading (0.54, P=0.01) and going to church/synagogue (HR=0.66, P<0.05) but not for caffeine (HR=0.61, P=0.15) and vitamin C (HR=0.68, P=0.07). While lifestyle behaviors around age 70 did not modify risk of late-life dementia, participation in activities and caffeine and supplemental vitamin intake around age 90 warrant further investigation.

Physical Activity and Alzheimer Disease: A Protective Association

OBJECTIVE

To explore whether being physically active can decrease Alzheimer disease (AD) risk.

PARTICIPANTS AND METHODS

We conducted a meta-analysis of prospective observational cohort studies reporting the association between physical activity (PA) and incident AD. Relevant articles were identified by title and abstract in the electronic databases PubMed, ScienceDirect, and Scopus using the keywords Alzheimer, Alzheimer disease, Alzheimer's, Alzheimer's disease, physical activity, sport, exercise, sedentary, fitness, and combinations thereof for articles published in any language up to February 15, 2016. Criteria for consideration included division of the study cohort by PA levels and sample size specification for each PA level group, quantification (number) of persons who had development of AD, and PA assessment during time off work (not just work time). We followed the MOOSE (Meta-analyses of Observational Studies in Epidemiology) recommendations and used the Newcastle-Ottawa scale for study quality assessment.

RESULTS

Ten high-quality studies were included in meta-analysis I (23,345 participants). Follow-up ranged from 3.9 to 31 years, and the participants' age ranged from 70 to 80 years. The pooled odds ratio for development of AD in participants who were more vs less physically active was 0.65 (95% CI, 0.56-0.74; P<.001; no publication bias [P=.24] but with heterogeneity among studies [I(2)=31.32%]). We could identify participants' adherence to international PA recommendations in 5 studies, which constituted meta-analysis II (10,615 participants). The pooled odds ratio for development of AD in participants who were active vs those who were inactive was 0.60 (95% CI, 0.51-0.71; P<.001; no publication bias [P=.34] and no heterogeneity [I(2)=5.63%]).

CONCLUSION

Although the limitations of self-reported PA data must be considered, regular PA performed by elderly people might play a certain protective role against AD.

Role of physical exercise in Alzheimer's disease

The benefits of physical exercise on the brain and general wellness are well recognised, but not particularly well known to the general public. Understanding the importance of integrating active behavior for overall health is crucial at any age and particularly for the elderly who are at risk of developing Alzheimer's disease (AD), a disease mainly affecting individuals aged >65 years. AD is a neurodegenerative disease characterized by extracellular senile plaques of amyloid-β, intracellular neurofibrillary tangles of the protein tau, brain atrophy and dementia. The beneficial effects of physical exercise have been observed on the maintenance of brain size and efficiency for the prevention of AD risks, such as obesity, hypertension and stroke. These effects are extended to individuals with, or at risk of dementia and other age-related neurodegenerative disorders. Accordingly, although extensive studies are required to fully understand the mechanisms by which physical exercise procures beneficial effects, data suggest the relevance of integrating physical exercise in the prevention and/or cure of AD, disease whose incidence is predicted to increase in the future. Such an increase, may pose medical, social and economical challenges for populations and the health care system worldwide. In the present review we assess the positive aspects of physical exercise with regard to prevention and cure of AD.

The effect of physical activity on cognitive function in patients with dementia: A meta-analysis of randomized control trials

Non-pharmacological therapies, such as physical activity interventions, are an appealing alternative or add-on to current pharmacological treatment of cognitive symptoms in patients with dementia. In this meta-analysis, we investigated the effect of physical activity interventions on cognitive function in dementia patients, by synthesizing data from 802 patients included in 18 randomized control trials that applied a physical activity intervention with cognitive function as an outcome measure. Post-intervention standardized mean difference (SMD) scores were computed for each study, and combined into pooled effect sizes using random effects meta-analysis. The primary analysis yielded a positive overall effect of physical activity interventions on cognitive function (SMD[95% confidence interval]=0.42[0.23;0.62], p<.01). Secondary analyses revealed that physical activity interventions were equally beneficial in patients with Alzheimer's disease (AD, SMD=0.38[0.09;0.66], p<.01) and in patients with AD or a non-AD dementia diagnosis (SMD=0.47[0.14;0.80], p<.01). Combined (i.e. aerobic and non-aerobic) exercise interventions (SMD=0.59[0.32;0.86], p<.01) and aerobic-only exercise interventions (SMD=0.41[0.05;0.76], p<.05) had a positive effect on cognition, while this association was absent for non-aerobic exercise interventions (SMD=-0.10[-0.38;0.19], p=.51). Finally, we found that interventions offered at both high frequency (SMD=0.33[0.03;0.63], p<.05) and at low frequency (SMD=0.64[0.39;0.89], p<.01) had a positive effect on cognitive function. This meta-analysis suggests that physical activity interventions positively influence cognitive function in patients with dementia. This beneficial effect was independent of the clinical diagnosis and the frequency of the intervention, and was driven by interventions that included aerobic exercise.

Physical activity and dementia: long-term follow-up study of adult twins

INTRODUCTION

Physical activity is associated with a decreased occurrence of dementia. In twins, we investigated the effect of persistent physical activity in adulthood on mortality due to dementia.

MATERIALS AND METHODS

Physical activity was queried in 1975 and 1981 from the members of the older Finnish Twin Cohort (n = 21,791), who were aged 24-60 years at the end of 1981. The subjects were divided into three categories according to the persistence of their vigorous physical activity. Dementia deaths were followed up to the end of 2011.

RESULTS

During the 29-year follow-up, 353 subjects died of dementia. In individual-based analyses the age- and sex-adjusted hazard ratio (HR) was 0.65 (95% CI 0.43-0.98) for subjects partaking in vigorous physical activities in both 1975 and 1981 compared to those who were inactive in both years. No significant change was observed after adjusting for potential confounding factors. The corresponding HR for within-pair comparisons of the less active twin versus the more active co-twin was 0.48 (95% CI 0.17-1.32). The results for analyses of the volume of physical activity were inconclusive.

CONCLUSIONS

Persistent vigorous leisure-time physical activity protects from dementia, and the effect appears to remain after taking into account childhood environment.

Exercise and cognitive functions in Parkinson's disease: Gender differences and disease severity

This study investigated the effect of a multimodal exercise program on executive functions and memory in people with Parkinson's disease, taking into account disease severity and gender. Twenty-three patients with Parkinson's disease (PD) were evaluated before and after a 6-month exercise program to improve executive functions and memory. We observed the effects of the intervention on executive functions (ability to abstract: p = .01), immediate memory (p= .04) and declarative episodic memory (p < .001). Women showed higher scores on declarative episodic memory (p = .03) than men, however there was no interaction between gender and the intervention. Regardless of sex and disease severity, these preliminary results indicate that the multimodal exercise seems to be effective in improving cognitive functions in patients with PD, suggesting that this program can be indicated as a preventive strategy to mitigate progressive cognitive deficits in the later stages of the disease.