Lifestyle and the risk of dementia in Japanese-american men

Combined healthy lifestyle behaviours and incident dementia: A systematic review and dose-response meta-analysis of cohort studies

BACKGROUND

The associations of combined healthy lifestyle behaviours and incident dementia have not been systematically reviewed and the dose-response relationship was uncertain.

OBJECTIVES

To evaluate the associations of combined healthy lifestyle behaviours with incident dementia and other cognitive outcomes, assess the dose-response relationship between the number of lifestyle behaviours and incident dementia, and summarise the adherence to healthy lifestyle behaviours.

DESIGN

Systematic review and meta-analysis.

METHODS

PubMed, EMBASE, Web of Science and PsycINFO were searched from inception to 20 Jan 2024. Cohort studies reporting associations of combined healthy lifestyle behaviours with incident dementia or other cognitive outcomes were included. We used the random-effects meta-analysis to pool the risk estimates and the robust error meta-regression method to examine the dose-response relationship. The methodological quality was assessed using the Newcastle-Ottawa Scale.

RESULTS

A total of 22 articles including 25 cohort studies mostly from high-income economics were included, with all assessed as high methodological quality. Adherence to a healthy lifestyle was associated with a decreased risk of incident dementia, either per healthy lifestyle behaviour increase (pooled hazard ratio 0.89, 95 % confidence interval 0.85-0.94) or the highest level versus the lowest level (pooled hazard ratio 0.61, 95 % confidence interval 0.49-0.76). An inverse, linear dose-response relationship (Pnon-linear = 0.845) between the number of healthy lifestyle behaviours and incident dementia was observed, with an 11 % risk reduction for each healthy behaviour increase. A relatively limited number of included studies indicated that adherence to a healthy lifestyle combination could yield benefits for cognitive decline, global cognition, memory and executive function. In addition, the adherence rates typically decreased as the number of healthy lifestyle behaviours increased.

CONCLUSIONS

Adherence to a healthy lifestyle was associated with a lower risk of incident dementia and other cognitive outcomes. It is important to find a subtle balance between the benefits and adherence. Further large cohort studies for combined lifestyle behaviours with specific cognitive outcomes and dose-response relationships are required, especially based on middle- and low-income populations.

REGISTRATION

The study was registered in PROSPERO (CRD42023418509).

TWEETABLE ABSTRACT

Engaging in a greater number of healthy lifestyle behaviours yields increased benefits in preventing dementia, albeit with lower adherence rates as a trade-off. Finding a delicate balance between the benefits and adherence is crucial.

A systematic review/meta-analysis of prevalence and incidence rates illustrates systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research

We investigate Alzheimer's disease and related dementia (ADRD) prevalence, incidence rate, and risk factors in individuals racialized as Asian and/or Asian-American and assess sample representation. Prevalence, incidence rate, risk factors, and heterogeneity of samples were assessed. Random-effects meta-analysis was conducted, generating pooled estimates. Of 920 records across 14 databases, 45 studies were included. Individuals racialized as Asian and/or Asian-American were mainly from Eastern and Southern Asia, had higher education, and constituted a smaller sample relative to non-Hispanic white cohorts. The average prevalence was 10.9%, ranging from 0.4% to 46%. The average incidence rate was 20.03 (12.01-33.8) per 1000 person-years with a range of 75.19-13.59 (12.89-14.33). Risk factors included physiological, genetic, psychological, behavioral, and social factors. This review underscores the systemic underrepresentation of individuals racialized as Asian and/or Asian-American in ADRD research and the need for inclusive approaches accounting for culture, language, and immigration status. HIGHLIGHTS: There is considerable heterogeneity in the prevalence of ADRD among studies of Asian-Americans. There is limited data on group-specific risk factors for ADRD among Asian-Americans. The average prevalence of (ADRD) among Asian-Americans was found to be 7.4%, with a wide range from 0.5% to 46%.

Transition to healthier lifestyle associated with reduced risk of incident dementia and decreased hippocampal atrophy

BACKGROUND

Research has estimated the associations of lifestyle at one-time point with the risk of dementia and hippocampal volume, but the impact of lifestyle transition on dementia and hippocampal volume remains unclear. This study aims to examine the associations of lifestyle transition with the risk of dementia and hippocampal volume.

METHODS

Based on data from the UK Biobank, a weighted lifestyle score was constructed by incorporating six lifestyle factors. Within each baseline lifestyle group (i.e., healthy, intermediate, and unhealthy), lifestyle transition was classified into decline, maintenance, and improvement. Cox proportional hazard regression was used to estimate the association of lifestyle transition and incident dementia (N = 16,305). A multiple linear regression model was used to estimate the association between lifestyle transition and hippocampal volume (N = 5849).

RESULTS

During a median follow-up period of 8.6 years, 120 (0.7 %) dementia events were documented. Among participants with healthy baseline lifestyles, the improvement group had a lower risk of incident dementia (HR: 0.18, 95 % CI: 0.04-0.81) and a larger hippocampal volume (β = 111.69, P = 0.026) than the decline group. Similar results were observed among participants with intermediate baseline lifestyles regarding dementia risk but not hippocampal volume. No benefits were observed in the improvement group among those with unhealthy baseline lifestyles.

LIMITATIONS

A lower incidence of dementia than other cohort study and this may have resulted in an underestimation of the risk of dementia.

CONCLUSIONS

Earlier transitions to healthier lifestyle were associated with reduced risk of incident dementia and decreased hippocampal atrophy.

Association of Life's Simple 7 with mild cognitive impairment in community-dwelling older adults in China: a cross-sectional study

Background

Life's Simple 7 (LS7), a metric composed of seven intervenable cardiovascular risk factors, is initiated by the American Heart Association to improve cardiovascular health. The components of LS7 have been reported as risk factors for dementia. However, few studies investigated the association between LS7 metric and mild cognitive impairment (MCI).

Methods

The study was carried out in a primary care facility between 8 June and 10 July 2022. A total of 297 community-dwelling residents aged 65 years or older were recruited. Sociodemographic, comorbidity, and lifestyle characteristics were collected through the questionnaires, and biological parameters were obtained from blood sample examinations. Logistic regression was used to analyze the association between LS7 scores (overall, behavioral, and biological) and individual components with MCI, adjusting sex, age, education, and cardiovascular disease (CVD).

Results

In comparison with the cognitively intact group (n = 195), the MCI group (n = 102) had a lower education level and a higher proportion of hypertension. Multivariate logistic regression analysis, adjusting sex, age, education, and CVD demonstrated a significant association between MCI and overall LS7 score [odd ratio = 0.805, 95% confidence interval (0.690, 0.939)] and biological score [odd ratio = 0.762, 95% confidence interval (0.602, 0.965)].

Conclusion

Life's Simple 7 was associated with MCI in community-dwelling older adults, indicating that LS7 could be used as guidance in the prevention of dementia in the community.

Weak Social Networks in Late Life Predict Incident Alzheimer's Disease: The Kuakini Honolulu-Asia Aging Study

BACKGROUND

We assessed 10-year longitudinal associations between late-life social networks and incidence of all-cause dementia (ACD), Alzheimer's disease (AD), and vascular dementia (VaD) in Japanese-American men.

METHODS

We prospectively analyzed, from baseline (1991-1993) through 1999-2000, 2636 initially nondemented Kuakini Honolulu-Asia Aging Study participants who remained dementia-free during the first 3 years of follow-up. Global cognition was evaluated by the Cognitive Abilities Screening Instrument (CASI); depressive symptoms by the 11-item Center for Epidemiologic Studies Depression (CES-D) Scale; and social networks by the Lubben Social Network Scale (LSNS). Median split of LSNS scores defined weak/strong social network groups. A panel of neurologists and geriatricians diagnosed and classified dementia; AD and VaD diagnoses comprised cases in which AD or VaD, respectively, were considered the primary cause of dementia.

RESULTS

Median (range) baseline age was 77 (71-93) years. Participants with weak (LSNS score ≤29) versus strong (>29) social networks had higher age-adjusted incidence (in person-years) of ACD (12.6 vs. 8.7; p = .014) and AD (6.7 vs. 4.0; p = .007) but not VaD (2.4 vs. 1.4; p = .15). Kaplan-Meier curves showed a lower likelihood of survival free of ACD (log-rank p < .0001) and AD (p = .0006) for men with weak networks. In Cox proportional hazards models adjusting for age, education, APOE ɛ4, prevalent stroke, depressive symptoms, and CASI score (all at baseline), weak networks predicted increased incidence of ACD (hazard ratio [HR] = 1.52, p = .009) and AD (HR = 1.67, p = .014) but not VaD (p > .2).

CONCLUSION

Weak social networks may heighten the risk of dementia and AD, underscoring the need to promote social connectedness in older adults.

Statistical Approaches for the Analysis of Combined Health-Related Factors in Association with Adult Cognitive Outcomes: A Scoping Review

BACKGROUND

Dementia prevention is a global health priority, and there is emerging evidence to support associations between individual modifiable health behaviors and cognitive function and dementia risk. However, a key property of these behaviors is they often co-occur or cluster, highlighting the importance of examining them in combination.

OBJECTIVE

To identify and characterize the statistical approaches used to aggregate multiple health-related behaviors/modifiable risk factors and assess associations with cognitive outcomes in adults.

METHODS

Eight electronic databases were searched to identify observational studies exploring the association between two or more aggregated health-related behaviors and cognitive outcomes in adults.

RESULTS

Sixty-two articles were included in this review. Fifty articles employed co-occurrence approaches alone to aggregate health behaviors/other modifiable risk factors, eight studies used solely clustering-based approaches, and four studies used a combination of both. Co-occurrence methods include additive index-based approaches and presenting specific health combinations, and whilst simple to construct and interpret, do not consider the underlying associations between co-occurring behaviors/risk factors. Clustering-based approaches do focus on underlying associations, and further work in this area may aid in identifying at-risk subgroups and understanding specific combinations of health-related behaviors/risk factors of particular importance in the scope of cognitive function and neurocognitive decline.

CONCLUSION

A co-occurrence approach to aggregating health-related behaviors/risk factors and exploring associations with adult cognitive outcomes has been the predominant statistic approach used to date, with a lack of research employing more advanced statistical methods to explore clustering-based approaches.

Harnessing the potential of machine learning and artificial intelligence for dementia research

Progress in dementia research has been limited, with substantial gaps in our knowledge of targets for prevention, mechanisms for disease progression, and disease-modifying treatments. The growing availability of multimodal data sets opens possibilities for the application of machine learning and artificial intelligence (AI) to help answer key questions in the field. We provide an overview of the state of the science, highlighting current challenges and opportunities for utilisation of AI approaches to move the field forward in the areas of genetics, experimental medicine, drug discovery and trials optimisation, imaging, and prevention. Machine learning methods can enhance results of genetic studies, help determine biological effects and facilitate the identification of drug targets based on genetic and transcriptomic information. The use of unsupervised learning for understanding disease mechanisms for drug discovery is promising, while analysis of multimodal data sets to characterise and quantify disease severity and subtype are also beginning to contribute to optimisation of clinical trial recruitment. Data-driven experimental medicine is needed to analyse data across modalities and develop novel algorithms to translate insights from animal models to human disease biology. AI methods in neuroimaging outperform traditional approaches for diagnostic classification, and although challenges around validation and translation remain, there is optimism for their meaningful integration to clinical practice in the near future. AI-based models can also clarify our understanding of the causality and commonality of dementia risk factors, informing and improving risk prediction models along with the development of preventative interventions. The complexity and heterogeneity of dementia requires an alternative approach beyond traditional design and analytical approaches. Although not yet widely used in dementia research, machine learning and AI have the potential to unlock current challenges and advance precision dementia medicine.

Association between Life’s Simple 7 and cerebrospinal fluid biomarkers of Alzheimer’s disease pathology in cognitively intact adults: the CABLE study

Introduction

This study sought to explore the association between Life’s Simple 7 (LS7) and cerebrospinal fluid (CSF) Alzheimer’s disease (AD) pathological biomarkers in the cognitively normal northern Chinese population.

Methods

From the Chinese Alzheimer’s Biomarker and LifestylE (CABLE) study, 1106 cognitively normal participants were enrolled. The mean age was 62.34 years, and 39.6% were female. LS7 scores were summed with each metric assigned 0, 1, or 2 scores. The multiple linear regression models were used to investigate the association between LS7 scores and CSF AD biomarkers.

Results

We found that LS7 scores were significantly associated with CSF AD pathologies, including Aβ42/40 (β = 0.034, P = .041), p-tau181 (β =  − 0.043, P = .006), and t-tau (β =  − 0.044, P = .003). In subscales, the biological metrics (blood pressure, cholesterol, glucose) were significantly related to CSF tau-related biomarkers. These associations were observed in the APOE ε4 allele non-carriers, yet not in carriers. The relationship of behavior metrics was found in the middle age and males.

Conclusion

Improving LS7 scores might do a favor to alleviate the pathology of AD in the preclinical stage, especially among the APOE ε4 allele non-carriers.

Leisure Activities and the Risk of Dementia: A Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVES

Leisure activities are major components of modifiable and healthy lifestyles and are proposed to help prevent the development of dementia. This study aimed to assess the effects of different types of leisure activities, including cognitive, physical, and social activities, on the incidence of all-cause dementia (ACD), Alzheimer disease (AD), and vascular dementia (VD).

METHODS

We performed a systematic review and meta-analysis of the Cochrane, PubMed, Embase, and Web of Science databases to identify longitudinal studies that examined associations between leisure activities and dementia. Relative risks (RRs) and 95% CIs were pooled using random-effects meta-analysis. Subgroup analyses were used to estimate potential effect modifiers. The study was registered with PROSPERO (CRD42019116857).

RESULTS

A total of 38 longitudinal studies, with 2,154,818 participants at baseline, 74,700 ACD cases, 2,848 AD cases, and 1,423 VD cases during follow-up, were included in the meta-analysis. The subgroup analyses showed that physical (RR 0.83, 95% CI 0.78-0.88), cognitive (RR 0.77; 95% CI 0.68-0.87), and social (RR 0.93; 95% CI 0.87-0.99) activities were associated with a decreased incidence of ACD. In addition, physical (RR 0.87; 95% CI 0.78-0.96) and cognitive (RR 0.66; 95% CI 0.52-0.85) activities were related to a reduced risk of AD. Physical activity (RR 0.67; 95% CI 0.53-0.85) was associated with a lower incidence of VD.

DISCUSSION

Our findings suggest that leisure activities are inversely associated with a risk of ACD, AD, and VD.

[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.

Novel Functional, Health, and Genetic Determinants of Cognitive Terminal Decline: Kuakini Honolulu Heart Program/Honolulu-Asia Aging Study

To investigate interindividual differences in cognitive terminal decline and identify determinants including functional, health, and genetic risk and protective factors, data from the Honolulu Heart Program/Honolulu-Asia Aging Study, a prospective cohort study of Japanese American men, were analyzed. The sample was recruited in 1965-1968 (ages 45-68 years). Longitudinal performance of cognitive abilities and mortality status were assessed from Exam 4 (1991-1993) through June 2014. Latent class analysis revealed 2 groups: maintainers retained relatively high levels of cognitive functioning until death and decliners demonstrated significant cognitive waning several years prior to death. Maintainers were more likely to have greater education, diagnosed coronary heart disease, and presence of the apolipoprotein E (APOE) ε2 allele and FOXO3 G allele (SNP rs2802292). Decliners were more likely to be older and have prior stroke, Parkinson's disease, dementia, and greater depressive symptoms at Exam 4, and the APOE ε4 allele. Findings support terminal decline using distance to death as the basis for modeling change. Significant differences were observed between maintainers and decliners 15 years prior to death, a finding much earlier compared to the majority of previous investigations.

Early-life educational attainment, APOE ε4 alleles, and incident dementia risk in late life

We examined the interactions between educational attainment and genetic susceptibility on dementia risk among adults over 60 years old. A total of 174,161 participants were free of dementia at baseline. The APOE ε4-related genetic risk was evaluated by the number of APOE ε4 alleles. The overall genetic susceptibility of dementia was evaluated by polygenetic risk score (PRS). Cox proportional hazards models were used to estimate the association between educational attainment and incident dementia. During a median of 8.9 years of follow-up, a total of 1482 incident cases of dementia were documented. After adjustment for covariates, we found that low education attainment was significantly associated with higher dementia risk in the APOE ε4 carriers, and such relation appeared to be stronger with the increasing number of ε4 alleles. In contrast, educational attainment was not associated with dementia risk in non-APOE ε4 carriers (P for multiplicative interaction = 0.006). In addition, we observed that the dementia risk associated with a combination of low educational attainment and high APOE ε4-related genetic risk was more than the addition of the risk associated with each of these factors (P for additive interaction < 0.001). We found similar significant interactions between educational attainment and PRS on both the multiplicative and additive scales on the dementia risk, mainly driven by the APOE genotype. These data indicate that higher educational attainment in early life may attenuate the risk for dementia, particularly among people with high genetic predisposition.

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.

Association of Life's Simple 7 with incident dementia and its modification by the apolipoprotein E genotype

INTRODUCTION

There is limited and inconsistent reporting on the association between Life's Simple 7 (LS7) and dementia in the elderly population.

METHODS

Based on the Washington Heights-Inwood Columbia Aging Project (WHICAP), LS7 scores were estimated to assess cardiovascular health status. Associations between LS7 scores and incident dementia were investigated by Cox proportional hazards models.

RESULTS

Among 1987 subjects, 291 incident cases of dementia were identified over a median follow-up of 5.84 years. Compared with subjects in the poor cardiovascular health group (scores 0 to 5), those in intermediate (6 to 9) and optimal (10 to 14) groups had lower dementia risk, with the hazard ratio (HR; 95% confidence interval) being 0.74 (0.54 to 1.00) and 0.59 (0.38 to 0.91), respectively. These results were significant in apolipoprotein E genotype ε4 (APOE ε4) allele non-carriers but not in carriers.

DISCUSSION

Higher LS7 scores are protective for dementia, especially among the APOE ε4 noncarriers.

Physical activity may not be associated with long-term risk of dementia and Alzheimer's disease

BACKGROUND

While it is well established that physical activity is associated with reduced risk of vascular and nonvascular outcomes as well as mortality, evidence on the association between physical activity and dementia is inconsistent. We aimed to assess the associations of physical activity with the risk of dementia and Alzheimer's disease (AD).

MATERIAL AND METHODS

We analysed data on 2394 apparently healthy men with good baseline cognitive function from the prospective population-based Kuopio Ischaemic Heart Disease study. We assessed habits of physical activity at baseline using a 12-month leisure time physical activity (LTPA) questionnaire. Using Cox regression, we calculated hazard ratios adjusted for body mass index, systolic blood pressure, smoking status, history of type-2 diabetes, total cholesterol, high-density lipoprotein cholesterol, alcohol consumption, history of coronary heart disease and high-sensitivity C-reactive protein.

RESULTS

During a median follow-up of 24.9 years (interquartile range: 18.3-26.9), 208 men developed dementia and 128 developed AD. Multivariable adjusted hazard ratios for dementia comparing top vs bottom tertiles of physical activity were 0.97 (95% confidence intervals: 0.69-1.38) for total physical activity volume, 0.96 (0.69-1.34) for conditioning LTPA volume and 1.13 (0.80-1.61) for total LTPA volume. Corresponding hazard ratios for AD were 1.19 (0.76-1.85), 0.98 (0.64-1.49) and 1.22 (0.77-1.93). Associations were consistent in analyses restricted to participants with ≥10 years of follow-up.

CONCLUSIONS

In middle-aged Caucasian men, various physical activity exposures were not associated with all-cause dementia or AD. Future studies should address biases due to reverse causation and regression dilution and should involve objective measures of physical activity.

The Active Brains Digital Intervention to Reduce Cognitive Decline in Older Adults: Protocol for a Feasibility Randomized Controlled Trial

BACKGROUND

Increasing physical activity, improving diet, and performing brain training exercises are associated with reduced cognitive decline in older adults.

OBJECTIVE

In this paper, we describe a feasibility trial of the Active Brains intervention, a web-based digital intervention developed to support older adults to make these 3 healthy behavior changes associated with improved cognitive health. The Active Brains trial is a randomized feasibility trial that will test how accessible, acceptable, and feasible the Active Brains intervention is and the effectiveness of the study procedures that we intend to use in the larger, main trial.

METHODS

In the randomized controlled trial (RCT), we use a parallel design. We will be conducting the intervention with 2 populations recruited through GP practices (family practices) in England from 2018 to 2019: older adults with signs of cognitive decline and older adults without any cognitive decline. Trial participants were randomly allocated to 1 of 3 study groups: usual care, the Active Brains intervention, or the Active Brains website plus brief support from a trained coach (over the phone or by email). The main outcomes are performance on cognitive tasks, quality of life (using EuroQol-5D 5 level), Instrumental Activities of Daily Living, and diagnoses of dementia. Secondary outcomes (including depression, enablement, and health care costs) and process measures (including qualitative interviews with participants and supporters) will also be collected. The trial has been approved by the National Health Service Research Ethics Committee (reference 17/SC/0463).

RESULTS

Results will be published in peer-reviewed journals, presented at conferences, and shared at public engagement events. Data collection was completed in May 2020, and the results will be reported in 2021.

CONCLUSIONS

The findings of this study will help us to identify and make important changes to the website, the support received, or the study procedures before we progress to our main randomized phase III trial.

TRIAL REGISTRATION

International Standard Randomized Controlled Trial Number 23758980; http://www.isrctn.com/ISRCTN23758980.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/18929.

Association between change in lifestyle and cognitive functions among elderly Koreans: findings from the Korean longitudinal study of aging (2006-2016)

BACKGROUND

South Korea is an aged society that continues to age rapidly. Therefore, the purpose of this study was to investigate the association between changes in lifestyle and cognitive functions in the South Korean elderly using a nationally representative survey.

METHODS

We analyzed data from the Korean Longitudinal Study of Aging (KLoSA) 2006-2016, a biannual panel survey. Multiple linear regression analysis was performed with repeated measurements data to examine the association between lifestyle change and cognitive functions over 2 years. Lifestyle combined the scores of four factors (smoking status, alcohol drinking status, body weight, and exercise), and then categorized them into four groups (Good→Good, Bad→Good, Good→Bad, and Bad→Bad) according to the two-year change. Cognitive functions were set according to the scores measured through the Korean Mini-Mental State Examination (K-MMSE).

RESULTS

Among females, the K-MMSE score was the highest in the Bad→Good group compared to the reference group, Bad→Bad (β = 0.914; SD = 3.744; p < .0001). The next highest scores were in the Good→Good group (β = 0.813; SD = 4.654; p = 0.0005) and the Good→Bad group (β = 0.475; SD = 4.542; p = 0.0481). Among males, only the K-MMSE of the Good→Good group was statistically significant (β = 0.509; SD = 3.245; p = 0.0077). The results of subgroup analysis showed that the K-MMSE scores of females who did not participate in any social activities were more affected by their lifestyle (Good-Good: β = 1.614; SD = 4.270; p = 0.0017, Bad-Good: β = 1.817; SD = 3.945; p < .0001). Subgroup analysis showed that females who started drinking more than a moderate amount of alcohol had lower K-MMSE scores (Good-Bad: β = - 2.636; SD = 2.915; p = 0.0011). Additionally, in both sexes, exercising, among the four lifestyle options, had a strong and significant association with higher K-MMSE scores.

CONCLUSIONS

Following a healthy lifestyle or improving an unhealthy lifestyle can help people prevent or slow down cognitive decline. Regularly engaging in an adequate amount of exercise can help the cognitive function of the elderly. Females, specifically, can experience positive effects on their cognitive function if they participate in social activities while maintaining healthy lifestyles, in particular not drinking too much alcohol.

Association between sedentary behavior and the risk of dementia: a systematic review and meta-analysis

An increasing number of original studies suggest that sedentary behavior is associated with the risk of dementia, but the results remain inconsistent and inconclusive. In this meta-analysis, we analyzed available observational epidemiological evidence to identify the association between sedentary behavior and the risk of dementia. We searched PubMed and Embase from their inception to March 2019 to identify observational studies examining the association between sedentary behavior and risk of dementia. Two authors independently extracted data and assessed study quality using predefined criteria. The Q statistics and I² methods were used to test for heterogeneity. The publication bias of the included studies was also estimated using Begg's and Egger's tests. We identified 18 relevant cohort studies involving 250,063 participants and 2269 patients with dementia. Pooled result showed that sedentary behavior was significantly associated with increased risk of dementia (RR = 1.30; 95% CI: 1.12-1.51). In addition, subgroup analyses by state, and controlling for the concomitant effects of age, sex, education were conducted for the increase of dementia risk, relating to sedentary, respectively. In general, these subgroup analyses showed no statistically significant differences. The results of our meta-analysis suggested that sedentary behavior was independently associated with a significantly increased risk of dementia, which might have important implications in conducting etiological studies for dementia and developing strategies for dementia prevention.

Contributions of Modifiable Risk Factors to Dementia Incidence: A Bayesian Network Analysis

OBJECTIVE

To determine and compare the contributions of modifiable risk factors (RFs) with the prevention of dementia in older adults.

DESIGN

A systematic review and Bayesian network meta-analysis (NMA). The observational group was set as a reference to collect all existing RFs and compare them with each other.

SETTING AND PARTICIPANTS

An exhaustive and comprehensive literature search strategy was used to identify relevant prospective cohort studies from several online databases from their inception to May 1, 2019. Participants without dementia were adults aged greater than 50 years.

MEASURES

The required data were extracted from the eligible studies to facilitate the Bayesian NMA.

RESULTS

Forty-three cohort studies with 277,294 participants were included in this NMA. Using the observation group as the reference, all defined RFs, except for antioxidants, were associated with lower risks of all-cause dementia [no sleep disturbances (odds ratio, OR 0.43, 95% credible interval, CrI 0.24-0.62), a high level of education (OR 0.50, 95% CrI 0.34-0.66), no history of diabetes (OR 0.57, 95% CrI 0.36-0.78), nonobese patients (OR 0.61, 95% CrI 0.39-0.83), no smoking history (OR 0.62, 95% CrI 0.45-0.79), living with family members (OR 0.67, 95% CrI 0.45-0.89), participation in physical exercise (OR 0.73, 95% CrI 0.46-0.94), abstinence from drinking (OR 0.78, 95% CrI 0.56-0.99), and no history of hypertension (OR 0.80, 95% CrI 0.65-0.96)].

CONCLUSIONS/RELEVANCE

The findings provide reliable support for the hypothesis that modifiable somatic and lifestyle factors are strong predictors of all-cause dementia.

Healthy lifestyle and the risk of Alzheimer dementia: Findings from 2 longitudinal studies

OBJECTIVE

To quantify the impact of a healthy lifestyle on the risk of Alzheimer dementia.

METHODS

Using data from the Chicago Health and Aging Project (CHAP; n = 1,845) and the Rush Memory and Aging Project (MAP; n = 920), we defined a healthy lifestyle score on the basis of nonsmoking, ≥150 min/wk moderate/vigorous-intensity physical activity, light to moderate alcohol consumption, high-quality Mediterranean-DASH Diet Intervention for Neurodegenerative Delay diet (upper 40%), and engagement in late-life cognitive activities (upper 40%), giving an overall score ranging from 0 to 5. Cox proportional hazard models were used for each cohort to estimate the hazard ratio (HR) and 95% confidence interval (CI) of the lifestyle score with Alzheimer dementia, and a random-effect meta-analysis was used to pool the results.

RESULTS

During a median follow-up of 5.8 years in CHAP and 6.0 years in MAP, 379 and 229 participants, respectively, had incident Alzheimer dementia. In multivariable-adjusted models, the pooled HR (95% CI) of Alzheimer dementia across 2 cohorts was 0.73 (95% CI 0.66-0.80) per each additional healthy lifestyle factor. Compared to participants with 0 to 1 healthy lifestyle factor, the risk of Alzheimer dementia was 37% lower (pooled HR 0.63, 95% CI 0.47-0.84) in those with 2 to 3 healthy lifestyle factors and 60% lower (pooled HR 0.40, 95% CI 0.28-0.56) in those with 4 to 5 healthy lifestyle factors.

CONCLUSION

A healthy lifestyle as a composite score is associated with a substantially lower risk of Alzheimer's dementia.

Association of body mass index with risk of cognitive impairment and dementia: A systematic review and meta-analysis of prospective studies

Controversies persist about the associations of body mass index (BMI) with risk of cognitive impairment and dementia. This study aimed to evaluate these associations from various aspects, in which Embase, PubMed and Cochrane databases were searched to identify prospective studies up to May 2019. Random-effects meta-analyses and dose-response meta-analysis were conducted, involving twenty-nine of 20,083 identified literatures. Meta-analysis showed that midlife underweight, obesity and late-life underweight conferred 1.39-, 1.31- and 1.64-fold excess risk for cognitive impairment and dementia, while late-life overweight and obesity conferred 21% and 25% reduced risk. In dose-response meta-analysis, all cause dementia (ACD), Alzheimer's disease (AD) and vascular dementia (VaD) risk in midlife was significantly elevated when BMI surpassed 29, 30 and 32 kg/m². AD risk in late-life was decreased when BMI was under 27 kg/m², while this protection for VaD was absent when BMI surpassed 39 kg/m². Higher BMI produced opposite exerted opposite effects on dementia in mid- and late-age population. Firstly reported, a dose-response relationship further supports the guideline from the standpoint of dementia prevention.

Twin studies on the association of physical activity with cognitive and cerebral outcomes

Regular physical activity (PA) offers positive effects on the human body. However, the effects of PA on cognition and in the brain are less clear. In this paper, we narratively review the relationship of PA with cognition and dementia, first from general perspective and then through genetically informed studies on the topic. Then we move on to imaging studies on exercise and brain anatomy first by presenting an overall picture of the topic and then discussing brain imaging studies addressing PA and brain structure in twins in more detailed way. Regarding PA and cognition or dementia, genetically informed studies are uncommon, even though the relationship between PA and cognitive ageing has been extensively studied. It is challenging to find twin pairs discordant for PA and dementia. Concerning brain imaging studies, among PA discordant young adult twin pairs, the more active co-twins showed larger gray matter volumes in striatal, prefrontal, and hippocampal regions and in electrophysiological studies automatic deviance-detection processes differed in brain regions involved with sensorimotor, visual and memory functions.

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.

Assessment of the Mid-Life Demographic and Lifestyle Risk Factors of Dementia Using Data from the Framingham Heart Study Offspring Cohort

BACKGROUND

Dementia is the leading cause of dependence and disability in the elderly population worldwide. However, currently there is no effective medication for dementia treatment. Therefore, identifying lifestyle-related risk factors including some that are modifiable may provide important strategies for reducing risk of dementia.

OBJECTIVE

This study aims to highlight associations between easily obtainable lifestyle risk factors in mid-life and dementia in later adulthood.

METHODS

Using data from the Framingham Heart Study Offspring cohort, we leveraged well-known classification models (decision tree classifier and random forests) to associate demographic and lifestyle behavioral data with dementia status. We then evaluated model performance by computing area under receiver operating characteristic (ROC) curve.

RESULTS

As expected, age was strongly associated with dementia. The analysis also identified 'widowed' marital status, lower BMI, and less sleep at mid-life as risk factors of dementia. The areas under the ROC curves were 0.79 for the decision tree, and 0.89 for the random forest model.

CONCLUSION

Demographic and lifestyle factors that are non-invasive and inexpensive to implement can be assessed in midlife and used to potentially modify the risk of dementia in late adulthood. Classification models can help identify associations between dementia and midlife lifestyle risk factors. These findings inform further research, in order to help public health officials develop targeted programs for dementia prevention.

Physical inactivity, cardiometabolic disease, and risk of dementia: an individual-participant meta-analysis

OBJECTIVE

To examine whether physical inactivity is a risk factor for dementia, with attention to the role of cardiometabolic disease in this association and reverse causation bias that arises from changes in physical activity in the preclinical (prodromal) phase of dementia.

DESIGN

Meta-analysis of 19 prospective observational cohort studies.

DATA SOURCES

The Individual-Participant-Data Meta-analysis in Working Populations Consortium, the Inter-University Consortium for Political and Social Research, and the UK Data Service, including a total of 19 of a potential 9741 studies.

REVIEW METHOD

The search strategy was designed to retrieve individual-participant data from prospective cohort studies. Exposure was physical inactivity; primary outcomes were incident all-cause dementia and Alzheimer's disease; and the secondary outcome was incident cardiometabolic disease (that is, diabetes, coronary heart disease, and stroke). Summary estimates were obtained using random effects meta-analysis.

RESULTS

Study population included 404 840 people (mean age 45.5 years, 57.7% women) who were initially free of dementia, had a measurement of physical inactivity at study entry, and were linked to electronic health records. In 6.0 million person-years at risk, we recorded 2044 incident cases of all-cause dementia. In studies with data on dementia subtype, the number of incident cases of Alzheimer's disease was 1602 in 5.2 million person-years. When measured <10 years before dementia diagnosis (that is, the preclinical stage of dementia), physical inactivity was associated with increased incidence of all-cause dementia (hazard ratio 1.40, 95% confidence interval 1.23 to 1.71) and Alzheimer's disease (1.36, 1.12 to 1.65). When reverse causation was minimised by assessing physical activity ≥10 years before dementia onset, no difference in dementia risk between physically active and inactive participants was observed (hazard ratios 1.01 (0.89 to 1.14) and 0.96 (0.85 to 1.08) for the two outcomes). Physical inactivity was consistently associated with increased risk of incident diabetes (hazard ratio 1.42, 1.25 to 1.61), coronary heart disease (1.24, 1.13 to 1.36), and stroke (1.16, 1.05 to 1.27). Among people in whom cardiometabolic disease preceded dementia, physical inactivity was non-significantly associated with dementia (hazard ratio for physical activity assessed >10 before dementia onset 1.30, 0.79 to 2.14).

CONCLUSIONS

In analyses that addressed bias due to reverse causation, physical inactivity was not associated with all-cause dementia or Alzheimer's disease, although an indication of excess dementia risk was observed in a subgroup of physically inactive individuals who developed cardiometabolic disease.

Joint impact of seven risk factors on incident dementia in elderly Japanese: the Ohsaki Cohort 2006 Study

BACKGROUND

This cohort study estimated the population attributable fraction (PAF) of seven combined major risk factors for incident dementia.

METHODS

We conducted a cohort study of 8563 community-dwelling individuals aged ≥ 65 years. In a baseline survey (2006), we collected data on major seven risk factors: diabetes mellitus, hypertension, obesity, physical inactivity, severe psychological distress, smoking, and low educational attainment. The total number of risk factors was applied as an exposure variable. Subjects were categorized into four groups according to the total number of risk factors they possessed (0, 1, 2, ≥ 3 risk factors). Data on incident dementia were retrieved from the public Long-term Care Insurance database. Hazard ratios (HRs) and 95% confidence interval (95% CI) were estimated using the Cox proportional regression model. We also calculated the PAF using HRs and the prevalences in our cohort data.

RESULTS

The number of cases of incident dementia was 577 (6.7%). A dose-response relationship between the total number of risk factors and incident dementia was observed; in comparison with no risk factors (reference), the age- and sex-adjusted HRs (95% CIs) were 1.25 (0.92-1.70) for one risk factor, 1.59 (1.18-2.15) for two, and 2.21 (1.62-3.01) for three or more (P trend < 0.001). If subjects had adhered to none of the risk factors, the PAF would have been 32.2%. If subjects had improved toward one better category, the PAF would have been 23.0%.

CONCLUSION

Our findings suggest that reducing the combined number of risk factors would contribute significantly to reducing the incidence of dementia.

Alzheimer's "Prevention" vs. "Risk Reduction": Transcending Semantics for Clinical Practice

The terms "prevention" and "risk reduction" are often used interchangeably in medicine. There is considerable debate, however, over the use of these terms in describing interventions that aim to preserve cognitive health and/or delay disease progression of Alzheimer's disease (AD) for patients seeking clinical care. Furthermore, it is important to distinguish between Alzheimer's disease prevention and Alzheimer's dementia prevention when using these terms. While prior studies have codified research-based criteria for the progressive stages of AD, there are no clear clinical consensus criteria to guide the use of these terms for physicians in practice. A clear understanding of the implications of each term will help guide clinical practice and clinical research. The authors explore the semantics and appropriate use of the terms "prevention" and "risk reduction" as they relate to AD in clinical practice.

Association of Cardiovascular Health Level in Older Age With Cognitive Decline and Incident Dementia

IMPORTANCE

Evidence is limited regarding the relation between cardiovascular health level and dementia risk.

OBJECTIVE

To investigate the association between cardiovascular health level, defined using the 7-item tool from the American Heart Association (AHA), and risk of dementia and cognitive decline in older persons.

DESIGN, SETTING, AND PARTICIPANTS

Population-based cohort study of persons aged 65 years or older from Bordeaux, Dijon, and Montpellier, France, without history of cardiovascular diseases or dementia at baseline who underwent repeated in-person neuropsychological testing (January 1999-July 2016) and systematic detection of incident dementia (date of final follow-up, July 26, 2016).

EXPOSURES

The number of the AHA's Life's Simple 7 metrics at recommended optimal level (nonsmoking, body mass index <25, regular physical activity, eating fish twice a week or more and fruits and vegetables at least 3 times a day, cholesterol <200 mg/dL [untreated], fasting glucose <100 mg/dL [untreated], and blood pressure <120/80 mm Hg [untreated]; score range, 0-7) and a global cardiovascular health score (range, 0-14; poor, intermediate, and optimal levels of each metric assigned a value of 0, 1, and 2, respectively).

MAIN OUTCOMES AND MEASURES

Incident dementia validated by an expert committee and change in a composite score of global cognition (in standard units, with values indicating distance from population means, 0 equal to the mean, and +1 and -1 equal to 1 SD above and below the mean).

RESULTS

Among 6626 participants (mean age, 73.7 years; 4200 women [63.4%]), 2412 (36.5%), 3781 (57.1%), and 433 (6.5%) had 0 to 2, 3 to 4, and 5 to 7 health metrics at optimal levels, respectively, at baseline. Over a mean follow-up duration of 8.5 (range, 0.6-16.6) years, 745 participants had incident adjudicated dementia. Compared with the incidence rate of dementia of 1.76 (95% CI, 1.38-2.15) per 100 person-years among those with 0 or 1 health metrics at optimal levels, the absolute differences in incident dementia rates for 2, 3, 4, 5, and 6 to 7 metrics were, respectively, -0.26 (95% CI, -0.48 to -0.04), -0.59 (95% CI, -0.80 to -0.38), -0.43 (95% CI, -0.65 to -0.21), -0.93 (95% CI, -1.18 to -0.68), and -0.96 (95% CI, -1.37 to -0.56) per 100 person-years. In multivariable models, the hazard ratios for dementia were 0.90 (95% CI, 0.84-0.97) per additional optimal metric and 0.92 (95% CI, 0.89-0.96) per additional point on the global score. Furthermore, the gain in global cognition associated with each additional optimal metric at baseline was 0.031 (95% CI, 0.009-0.053) standard units at inclusion, 0.068 (95% CI, 0.045-0.092) units at year 6, and 0.072 (95% CI, 0.042-0.102) units at year 12.

CONCLUSIONS AND RELEVANCE

In this cohort of older adults, increased numbers of optimal cardiovascular health metrics and a higher cardiovascular health score were associated with a lower risk of dementia and lower rates of cognitive decline. These findings may support the promotion of cardiovascular health to prevent risk factors associated with cognitive decline and dementia.

Chest width, waist circumference, and thigh circumference are predictors of dementia

OBJECTIVE

Few studies have investigated the relationship between specific body measures and dementia.

METHODS

Three-dimensional anthropometric body surface scanning data containing 38 body measures were collected from 6831 participants from the health examination department of a medical center in Taiwan during 2000 to 2008, and 236 dementia cases were identified during the 10-year follow-up. A multiple Cox regression analysis was performed.

RESULTS

Specific body measures, namely chest width (hazard ratio [HR] = 0.90; 95% confidence interval [CI] = 0.83-0.98), and right thigh circumference (HR = 0.93; 95% CI = 0.90-0.96), were protective predictors to dementia occurrence. Waist circumference (HR = 1.03; 95% CI = 1.02-1.05) was a risk factor in dementia occurrence. Among the combinations, dementia risk was higher in participants with a larger waist circumference and a smaller right thigh circumference, with the highest HR of 2.49 (95% CI = 1.54-4.03).

CONCLUSION

The body measures provide clues for future applications and scientific merits in both clinical and preventive medicine.

Risk factors for dementia in the ninth decade of life and beyond: a study of the Lothian birth cohort 1921

BACKGROUND

With increasing numbers of people surviving beyond eighty years, this section of the population demands attention to reduce the impact of dementia. In order to develop effective preventative strategies, it is essential to understand age-specific risk factor profiles for dementia: do risk factors for dementia in those in their sixties and seventies persist into oldest age? The aims of this study were to determine incident dementia and to investigate the risk profile for dementia from age 79 to 95 years in a well-characterised cohort.

METHODS

Participants underwent intelligence testing at age 11 and were followed-up from at 79 years of age. Variables included: age, sex, age 11 IQ, APOE ɛ4, education, diabetes, hypertension, statin use, physical activity at leisure and in occupation, symptoms of depression, height, number of teeth, body mass index, blood pressure, cholesterol and HbA1c. Dementia cases were ascertained from death certificates, electronic patient records and clinical reviews. Logistic regression analysis determined the degree of risk for dementia associated with each variable. Analyses were completed both with and without the physical activity variables due to the significant number of missing data for these variables.

RESULTS

Of the eligible cohort, n = 410 participants remained dementia-free and n = 110 had developed probable dementia. When logistic regression analyses contained all variables, complete data was available for n = 234 (n = 48 with dementia). Results demonstrated that positive APOE ɛ4 carrier status (OR: 2.15, 95% CI: 1.04, 4.42) and greater lifetime physical activity (OR: 1.14, 95% CI: 1.02, 1.28) increased the risk for dementia. A reduction in risk for dementia was seen for hypertension (OR: 0.47, 95% CI: 0.23, 0.98). When physical activity variables were excluded, the number with complete data increased to n = 377 (n = 80 with dementia). APOE ɛ4 remained significant (OR: 2.37; 95% CI: 1.37, 4.07), as did hypertension (OR: 0.55; 95% CI: 0.32, 0.93).

CONCLUSIONS

Dementia incidence was consistent with expected rates. The risk profile for dementia in this cohort of participants aged 79-95 confirmed previous findings that risk factors differ for those over 79 years. Further evidence is recommended in order that the risk profile for this age group can be accurately determined.

The impact of residential status on cognitive decline among older adults in China: Results from a longitudinal study

BACKGROUND

Residential status has been linked to numerous determinants of health and well-being. However, the influence of residential status on cognitive decline remains unclear. The purpose of this research was to assess the changes of cognitive function among older adults with different residential status (urban residents, rural-to-urban residents, rural residents, and urban-to-rural residents), over a 12-year period.

METHODS

We used five waves of data (2002, 2005, 2008/2009, 2011/2012, and 2014) from the Chinese Longitudinal Healthy Longevity Survey with 17,333 older adults age 65 and over who were interviewed up to five times. Cognitive function was measured by the Mini Mental State Examination (MMSE). Multilevel models were used regarding the effects of residential status after adjusting for demographic characteristics, socioeconomic factors, family support, health behaviors, and health status.

RESULTS

After controlling for covariates, significant differences in cognitive function were found across the four groups: rural-to-urban and rural residents had a higher level of cognition than urban residents at baseline. On average, cognitive function decreased over the course of the study period. Rural-to-urban and rural residents demonstrated a faster decline in cognitive function than urban residents.

CONCLUSIONS

This study suggests that residential status has an impact on the rate of changes in cognition among older adults in China. Results from this study provide directions for future research that addresses health disparities, particularly in countries that are undergoing significant socioeconomic transitions.

Factors influencing executive function by physical activity level among young adults: a near-infrared spectroscopy study

[Purpose] Prevention of dementia requires early intervention against it. To ensure that early interventions are effective it is crucial to study the cognitive functions related to dementia in young adulthood. Moreover, it is needed not only to verify the cognitive function test but also to elucidate the actual brain activity and the influence of related factors on the brain activity. To investigate the factors influencing cognitive function among young adults and examine the differences in executive function by physical activity level. [Subjects and Methods] Forty healthy university students (mean age, 20.4 years) were classified into two groups by cognitive function score (HIGH and LOW), determined according to Trail Making Test performance and Stroop task processing time. We then assessed what factors were related to cognitive function by logistic regression analysis. Executive function was determined by brain blood flow using near-infrared spectroscopy during the Stroop task, and was then compared by physical activity levels (determined according to number of steps per hour). [Results] Full-scale Intelligence Quotient according to the 3rd Wechsler Adult Intelligent Scale and number of steps per hour influenced cognitive function score, with odds ratios of 1.104 and 1.012, respectively. Oxy-hemoglobin concentrations in areas related to executive function during the Stroop task were significantly higher among those in the high physical activity group than among those in the low physical activity group. [Conclusion] The study revealed that Full-scale Intelligence Quotient and a number of steps per hour are factors associated with the cognitive functions in young adulthood. In addition, activity in execution function related area was found to be significantly higher in the high physical activity group than in the low physical activity group, suggesting the importance of physical activity for enhancing young adulthood cognitive functions.

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.

Neuropathologic comorbidity and cognitive impairment in the Nun and Honolulu-Asia Aging Studies

OBJECTIVE

To examine frequencies and relationships of 5 common neuropathologic abnormalities identified at autopsy with late-life cognitive impairment and dementia in 2 different autopsy panels.

METHODS

The Nun Study (NS) and the Honolulu-Asia Aging Study (HAAS) are population-based investigations of brain aging that included repeated cognitive assessments and comprehensive brain autopsies. The neuropathologic abnormalities assessed were Alzheimer disease (AD) neuropathologic changes, neocortical Lewy bodies (LBs), hippocampal sclerosis, microinfarcts, and low brain weight. Associations with screening tests for cognitive impairment were examined.

RESULTS

Neuropathologic abnormalities occurred at levels ranging from 9.7% to 43%, and were independently associated with cognitive impairment in both studies. Neocortical LBs and AD changes were more frequent among the predominantly Caucasian NS women, while microinfarcts were more common in the Japanese American HAAS men. Comorbidity was usual and very strongly associated with cognitive impairment. Apparent cognitive resilience (no cognitive impairment despite Braak stage V) was strongly associated with minimal or no comorbid abnormalities, with fewer neocortical AD lesions, and weakly with longer interval between final testing and autopsy.

CONCLUSIONS

Total burden of comorbid neuropathologic abnormalities, rather than any single lesion type, was the most relevant determinant of cognitive impairment in both cohorts, often despite clinical diagnosis of only AD. These findings emphasize challenges to dementia pathogenesis and intervention research and to accurate diagnoses during life.

Target risk factors for dementia prevention: a systematic review and Delphi consensus study on the evidence from observational studies

OBJECTIVE

Dementia has a multifactorial etiology, but the importance of individual health and lifestyle related risk factors is often uncertain or based on few studies. The goal of this paper is to identify the major modifiable risk factors for dementia as a first step in developing an effective preventive strategy and promoting healthy late life cognitive functioning.

METHODS

A mixed-method approach combined findings from a systematic literature review and a Delphi consensus study. The literature search was conducted in PubMed and updated an earlier review by the United States National Institutes of Health from 2010. We reviewed the available evidence from observational epidemiological studies. The online Delphi study asked eight international experts to rank and weigh each risk factor for its importance for dementia prevention.

RESULTS

Out of 3127 abstracts, 291 were included in the review. There was good agreement between modifiable risk factors identified in the literature review and risk factors named spontaneously by experts. After triangulation of both methods and re-weighting by experts, strongest support was found for depression, (midlife) hypertension, physical inactivity, diabetes, (midlife) obesity, hyperlipidemia, and smoking, while more research is needed for coronary heart disease, renal dysfunction, diet, and cognitive activity.

CONCLUSIONS

Findings provide good support for several somatic and lifestyle factors and will be used to inform the design of a new multicenter trial into dementia prevention.

Life experience and demographic influences on cognitive function in older adults

OBJECTIVE

We examined the influence of a broad spectrum of life experiences on longitudinal cognitive trajectories in a demographically diverse sample of older adults.

METHOD

Participants were 333 educationally, ethnically, and cognitively diverse older adults enrolled in a longitudinal aging study. Mixed-effects regression was used to measure baseline status in episodic memory, executive functioning, and semantic memory and change in a global cognition factor defined by change in these 3 domain-specific measures. We examined effects of life experience variables (literacy, childhood socioeconomic status, morphometric measures of physical development, life course physical and recreational activity) on longitudinal cognitive trajectories, covarying for age, apolipoprotein E (APOE) genotype and demographics (education, ethnicity, language).

RESULTS

Non-Latino Whites had higher baseline cognition, but life experience variables attenuated ethnic differences in cognitive scores. Age, literacy, childhood socioeconomic status, and physical activity significantly influenced baseline cognition. Age, APOE ε4, and decline in intellectually and socially stimulating recreational activity from mid to late life were independently associated with increased late life cognitive decline. Higher literacy and late life recreational activity were associated with less decline. Literacy had similar effects for English and Spanish readers/speakers. Bilingual English and Spanish speakers did not differ from English Speakers in cognitive performance.

CONCLUSIONS

Life experience variables, especially literacy level, were strongly related to baseline cognition and substantially attenuated effects of race/ethnicity and education. Cognitive change was best explained by age, APOE ε4, literacy, and current recreational activities. Literacy had robust associations with baseline cognition and cognitive change in both English and Spanish speakers.

Body mass index in dementia

This review comprehensively examines the current knowledge on the relationship between body mass index (BMI) and dementia. The association between BMI and cognition is complex: in younger adults, higher BMIs are associated with impaired cognition. Overweight and obesity in middle age are linked to increased future dementia risk in old age. However, when examined in old age, higher BMIs are associated with better cognition and decreased mortality. Little is known about the optimal BMI for well-being and survival in populations already suffering from dementia. Lifetime trends in weight, rather than single measures, might predict prognosis better and help untangle these apparent contradictions. Thus, the need arises to properly monitor BMI trends in affected dementia patients. Registries can include BMI, improving the management of dementia patients throughout the whole course of the disease. The role of central obesity and systemic inflammation on brain pathology and cognitive decline are discussed in this review. Understanding the life-course changes in BMI and their influence on dementia risk, cognitive prognosis and mortality after diagnosis may provide new insights into the underlying pathophysiology of dementia and shape possible intervention and treatment strategies.

Clustering of midlife lifestyle behaviors and subsequent cognitive function: a longitudinal study

OBJECTIVES

We examined the association between individual and clustered lifestyle behaviors in middle age and later in cognitive functioning.

METHODS

Middle-aged participants (n = 2430) in the Supplémentation en Vitamines et Minéraux Antioxydant study self-reported their low physical activity, sedentary behavior, alcohol use, smoking, low fruit and vegetable consumption, and low fish consumption. We assessed cognition 13 years later via 6 neuropsychological tests. After standardization, we summed the scores for a composite cognitive measure. We estimated executive functioning and verbal memory scores using principal component analysis. We estimated the mean differences (95% confidence intervals [CIs]) in cognitive performance by the number of unhealthy behaviors using analysis of covariance. We identified latent unhealthy behavior factor via structural equation modeling.

RESULTS

Global cognitive function and verbal memory were linearly, negatively associated with the number of unhealthy behaviors: adjusted mean differences = -0.36 (95% CI = -0.69, -0.03) and -0.46 (95% CI = -0.80, -0.11), respectively, per unit increase in the number of unhealthy behaviors. The latent unhealthy behavior factor with low fruit and vegetable consumption and low physical activity as main contributors was associated with reduced verbal memory (RMSEA = 0.02; CFI = 0.96; P = .004). No association was found with executive functioning.

CONCLUSIONS

Comprehensive public health strategies promoting healthy lifestyles might help deter cognitive aging.

Preventing dementia: how lifestyle in midlife affects risk

PURPOSE OF REVIEW

Dementia is a worldwide health priority, with increasing public health burden and thus need for preventive strategies. Although many associations are proposed, there has been lack of sufficient evidence or demonstration of modifiability. This review will discuss the methodological challenges and the most established, controversial and novel modifiable midlife risk factors.

RECENT FINDINGS

There has been a shift towards a life-course approach, with large cohort longitudinal studies helping to untangle 'windows of opportunity' or reverse causation with vascular factors (hypertension and BMI), hormone replacement therapy and depression. Other vascular factors, such as hyperglycaemia, have now been approached as a continuum and BMI/alcohol as U-shaped associations. There is evidence regarding associations or mechanisms for personality, insomnia, cognitive stimulation and social activities, head injury, diet, and reproductive and oral health. Environmental considerations such as passive smoke, noise and hygiene exposure are also explored.

SUMMARY

Increasing evidence of associations from midlife will guide the shift to interventional studies from the midlife period. However, research challenges are such that the ideal studies may be impossible, although, for numerous factors, it has been argued that other known adverse health effects justify initiating or continuing health interventions in the absence of this evidence.

The neuropathology of sport

The benefits of regular exercise, physical fitness and sports participation on cardiovascular and brain health are undeniable. Physical activity reduces the risk for cardiovascular disease, type 2 diabetes, hypertension, obesity, and stroke, and produces beneficial effects on cholesterol levels, antioxidant systems, inflammation, and vascular function. Exercise also enhances psychological health, reduces age-related loss of brain volume, improves cognition, reduces the risk of developing dementia, and impedes neurodegeneration. Nonetheless, the play of sports is associated with risks, including a risk for mild TBI (mTBI) and, rarely, catastrophic traumatic injury and death. There is also growing awareness that repetitive mTBIs, such as concussion and subconcussion, can occasionally produce persistent cognitive, behavioral, and psychiatric problems as well as lead to the development of a neurodegeneration, chronic traumatic encephalopathy (CTE). In this review, we summarize the beneficial aspects of sports participation on psychological, emotional, physical and cognitive health, and specifically analyze some of the less common adverse neuropathological outcomes, including concussion, second-impact syndrome, juvenile head trauma syndrome, catastrophic sudden death, and CTE. CTE is a latent neurodegeneration clinically associated with behavioral changes, executive dysfunction and cognitive impairments, and pathologically characterized by frontal and temporal lobe atrophy, neuronal and axonal loss, and abnormal deposits of paired helical filament (PHF)-tau and 43 kDa TAR deoxyribonucleic acid (DNA)-binding protein (TDP-43). CTE often occurs as a sole diagnosis, but may be associated with other neurodegenerative disorders, including motor neuron disease (CTE-MND). Although the incidence and prevalence of CTE are not known, CTE has been reported most frequently in American football players and boxers. Other sports associated with CTE include ice hockey, professional wrestling, soccer, rugby, and baseball.

Healthy lifestyles reduce the incidence of chronic diseases and dementia: evidence from the Caerphilly cohort study

Background

Healthy lifestyles based on non-smoking, an acceptable BMI, a high fruit and vegetable intake, regular physical activity, and low/moderate alcohol intake, are associated with reductions in the incidence of certain chronic diseases, but to date there is limited evidence on cognitive function and dementia.

Methods

In 1979 healthy behaviours were recorded on 2,235 men aged 45–59 years in Caerphilly, UK. During the following 30 years incident diabetes, vascular disease, cancer and death were recorded, and in 2004 cognitive state was determined.

Findings

Men who followed four or five of the behaviours had an odds ratio (OR) and confidence intervals (CI) for diabetes, corrected for age and social class, of 0.50 (95% CI: 0.19, 1.31; P for trend with increasing numbers of healthy behaviours <0.0005). For vascular disease the OR was 0.50 (95% CI: 0.30, 0.84; P for trend <0.0005), and there was a delay in vascular disease events of up to 12 years. Cancer incidence was not significantly related to lifestyle although there was a reduction associated with non-smoking (OR: 0.65; 95% CI: 0.54, 0.79). All-cause mortality was reduced in men following four or five behaviours (OR 0.40; 95% CI: 0.24, 0.67; P for trend <0.005).

After further adjustment for NART, the OR for men following four or five healthy behaviours was 0.36 (95% CI: 0.12, 1.09; P for trend <0.001) for cognitive impairment, and 0.36 (95% CI: 0.07, 1.99; P for trend <0.02) for dementia.

The adoption of a healthy lifestyle by men was low and appears not to have changed during the subsequent 30 years, with under 1% of men following all five of the behaviours and 5% reporting four or more in 1979 and in 2009.

Interpretation

A healthy lifestyle is associated with increased disease-free survival and reduced cognitive impairment but the uptake remains low.

Nutrition and neurodegeneration: epidemiological evidence and challenges for future research

The prevention of dementias, such as Alzheimer's disease (AD), is a growing public health concern, due to a lack of effective curative treatment options and a rising global prevalence. Various potential risk or preventive factors have been suggested by epidemiological research, including modifiable lifestyle factors such as diet. Current epidemiological data are in favour of a protective role of certain micronutrients (B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish) in the prevention of cognitive decline and dementia/AD. Some factors have been targeted by interventions tested in randomized controlled trials (RCTs), but many of the results are conflicting with observational evidence. Epidemiological analysis of the relations between nutrient consumption and cognitive decline is complex and it is highly unlikely that a single component plays a major role. In addition, since multiple factors across the life course influence brain function in late life, multidomain interventions might be more promising in the prevention of cognitive decline and dementia/AD. Designing such trials remains very challenging for researchers. The main objective of this paper is to review the epidemiologic data linking potential protective factors to cognitive decline or dementia/AD, focusing particularly on the roles of adiposity, caloric restriction, micro (group B vitamins related to homocysteine metabolism, the anti-oxidant vitamins C and E, flavonoids, polyunsatured omega-3 fatty acids, vitamin D) and macronutrients (fish). Limitations of the current data, divergence with results of interventional prevention studies and challenges for future research are discussed.

Changes in Mini-Mental State Examination score in Alzheimer's disease patients after stopping habitual drinking

BACKGROUND

Globally, Alzheimer's disease (AD) is becoming an increasing problem as the population ages, and the effects of lifestyle factors on cognitive decline need to be better understood. This study examined the effects of alcohol abstinence on cognitive decline in AD.

METHODS

Cognitive function after alcohol abstinence was retrospectively reviewed in AD patients (high and low alcohol consumption groups) and then compared with an alcohol-naïve AD group. The alcohol-naïve AD group included 18 outpatients with no history of habitual drinking. The alcohol-abstinence AD group included 20 outpatients who stopped drinking after their diagnoses. The latter group was classified into high and low groups depending on the amount of they drank before abstinence. Cognitive function was evaluated with the Mini-Mental State Examination at baseline, 6 months, and 12 months. For statistical analyses, a repeated measures, two-factor anova and post-hoc multiple comparisons were performed using the Bonferroni method.

RESULTS

There was a significant effect of time on Mini-Mental State Examination score, but there was no difference in the baseline scores of the alcohol-naïve and alcohol-abstinence AD groups. The score was significantly lower at 6 and 12 months than at baseline in the alcohol-naïve group, but no significant difference was seen in the alcohol-abstinence group. There was a significant interaction between time and alcohol consumption subgroup on the score, with no difference in baseline score between the low and high consumption groups. The score was significantly lower only in the high consumption group at 12 months. CONCLUSIONS : In AD patients with a history of habitual drinking, abstinence was effective for reducing cognitive decline during the clinical course. However, such an effect was not seen in patients who had consumed high amounts of alcohol before diagnosis of AD.

Body weight variability in midlife and risk for dementia in old age

OBJECTIVE

To analyze the relationship between body weight variability and dementia more than 3 decades later.

METHODS

The measurement of body weight variability was based on 3 successive weight recordings taken from over 10,000 apparently healthy tenured working men participating in the Israel Ischemic Heart Disease study, in which cardiovascular risk factors and clinical status were assessed in 1963, 1965, and 1968, when subjects were 40-70 years of age. Groups of men were stratified according to quartiles of SD of weight change among 3 measurements (1963/1965/1968): ≤ 1.15 kg, 1.16-1.73 kg, 1.74-2.65 kg, and ≥ 2.66 kg. The prevalence of dementia was assessed more than 36 years later in approximately one-sixth of them who survived until 1999/2000 (minimum age 76 years) and underwent cognitive evaluation (n = 1,620).

RESULTS

Survivors' dementia prevalence rates were 13.4%, 18.4%, 20.1%, and 19.2% in the first to fourth quartiles of weight change SD, respectively (p for trend = 0.034). Compared to the first quartile of weight change SD and adjusted for diabetes mellitus, body height, and socioeconomic status, a multivariate analysis demonstrated that the odds ratio for dementia was 1.42 (95% confidence interval [CI] 0.95-2.13), 1.59 (95% CI 1.05-2.37), and 1.74 (95% CI 1.14-2.64) in quartiles 2-4 of weight change SD respectively. This relationship was independent of the direction of weight changes.

CONCLUSION

Midlife variations in weight may antecede late-life dementia.

The combined effects of healthy lifestyle behaviors on all cause mortality: a systematic review and meta-analysis

OBJECTIVE

Lifestyle factors are related to mortality. Although much is known about the impact of single factors, the current evidence about the combined effects of lifestyle behaviors on mortality has not yet been systematically compiled.

METHOD

We searched Medline, Embase, Global Health, and Somed up to February 2012. Prospective studies were selected if they reported the combined effects of at least three of five lifestyle factors (obesity, alcohol consumption, smoking, diet, and physical activity). The mean effect sizes that certain numbers of combined lifestyle factors have on mortality were compared to the group with the least number of healthy lifestyle factors by meta-analysis. Sensitivity analyses were conducted to explore the robustness of the results.

RESULTS

21 studies (18 cohorts) met the inclusion criteria of which 15 were included in the meta-analysis that comprised 531,804 people with a mean follow-up of 13.24 years. The relative risks decreased proportionate to a higher number of healthy lifestyle factors for all cause mortality. A combination of at least four healthy lifestyle factors is associated with a reduction of the all cause mortality risk by 66% (95% confidence interval 58%-73%).

CONCLUSION

Adherence to a healthy lifestyle is associated with a lower risk of mortality.