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

Physical activity initiated from midlife on risk of dementia and cognitive impairment: The Health and Retirement Study

BACKGROUND

Physical activity is associated with lower risk of dementia and cognitive impairment, but existing randomized controlled trials have shown conflicting results. As cognitive decline occurs decades before the onset of dementia, physical activity interventions initiated in late life may have missed the potential window for prevention. An ideal trial of physical activity initiated from midlife and lasts till incident dementia and cognitive impairment in late life is not feasible. We aimed to estimate the effectiveness of a hypothetical physical activity intervention initiated from midlife on reducing dementia and cognitive impairment by emulating target trials using observational data.

METHODS

The Health and Retirement Study was used to emulate target trials among noninstitutionalized participants aged 45 to 65 years with normal cognition who were physically inactive in the previous 2 years. Cognitive status was determined based on Langa-Weir classification of cognitive function (including immediate and delayed word recall tests, serial sevens subtraction, counting backward). Individuals were categorized as initiating physical activity or not, based on the self-reported physical activity. Intention-to-treat and per-protocol analysis were conducted with pooled logistic regression models with inverse-probability of treatment and censoring weights to estimate risk ratios (RRs), and 95% confidence intervals (95% CIs) were calculated with 200 sets of bootstrapping.

RESULTS

Among 1505 participants (average age 57.6 ± 4.8 years, 67% women, 76.5% White), 72 cases of dementia and 409 cases of cognitive impairment occurred. After 12 years of follow-up, physical activity reduced dementia (RR = 0.70, 95% CI: 0.43, 0.99) for intention-to-treat analysis, and reduced dementia (RR = 0.51, 95% CI: 0.19, 0.99) and cognitive impairment (RR = 0.77, 95% CI: 0.61, 0.92) for per-protocol analysis. No significant reduction was found among older adults.

CONCLUSIONS

Physical activity initiated during midlife may reduce dementia and cognitive impairment in late life, which highlights the importance of preventing cognitive outcomes at an earlier stage of life.

Effect of vigorous-intensity physical activity on incident cognitive impairment in high-risk hypertension

INTRODUCTION

We investigated the effect vigorous physical activity (VPA) on the risk of incident mild cognitive impairment (MCI) and probable dementia among individuals with high-risk hypertension.

METHODS

Baseline self-reported frequency of VPA was categorized into low VPA (<1 session/week), and high VPA (≥1 session/week). We used multivariate Cox regression analysis to examine the association of VPA categories with incident MCI and probable dementia events.

RESULTS

Participants in the high VPA category, compared with low VPA, experienced lower events rates (per 1000 person-years) of MCI (13.9 vs 19.7), probable dementia (6.3 vs 9.0), and MCI/probable dementia (18.5 vs 25.8). In the multivariate Cox regression model, high VPA, compared with low VPA, was associated with lower risk of MCI, probable dementia, and MCI/probable dementia (HR [95% CI]: 0.81 [0.68-0.97], 0.80 [0.63-1.03], and 0.82 [0.70-0.96]), respectively.

DISCUSSION

This study provides evidence that VPA may preserve cognitive function in high-risk patients with hypertension.

HIGHLIGHTS

Hypertension is associated with an increased risk of cognitive impairment Physical activity (PA) is associated with a lower risk of decline in cognition The effect of ≥1 sessions of vigorous-intensity PA (VPA) per week was assessed This analysis included SPRINT MIND trial participants with high-risk hypertension ≥1 VPA sessions/week was associated with lower risk of future cognitive impairment.

The impact of exercise on blood-based biomarkers of Alzheimer's disease in cognitively unimpaired older adults

Physical activity is a promising preventative strategy for Alzheimer's disease: it is associated with lower dementia risk, better cognition, greater brain volume and lower brain beta-amyloid. Blood-based biomarkers have emerged as a low-cost, non-invasive strategy for detecting preclinical Alzheimer's disease, however, there is limited literature examining the effect of exercise (a structured form of physical activity) on blood-based biomarkers. The current study investigated the influence of a 6-month exercise intervention on levels of plasma beta-amyloid (Aβ42, Aβ40, Aβ42/40), phosphorylated tau (p-tau181), glial fibrillary acidic protein (GFAP) and neurofilament light (NfL) chain in cognitively unimpaired older adults, and as a secondary aim, whether blood-based biomarkers related to cognition. Ninety-nine community-dwelling older adults (69.1 ± 5.2) were allocated to an inactive control, or to moderate or high intensity exercise groups where they cycled twice weekly for six months. At baseline and six months (post-intervention), fasted blood was collected and analysed using single molecule array (SIMOA) assays, and cognition was assessed. Results demonstrated no change in levels of any plasma biomarker from pre- to post-intervention. At baseline, higher NfL was associated with poorer cognition (β = -0.33, SE = 0.13, adjusted p = .042). Exploratory analyses indicated higher cardiorespiratory fitness was associated with higher NfL and GFAP levels in apolipoprotein E (APOE) ε4 non-carriers compared to ε4 carriers (NfL, β = -0.43, SE = 0.19, p = .029; GFAP, β = -0.41, SE = 0.20, p = .044), though this association was mediated by body mass index (BMI). These results highlight the importance of considering BMI in analysis of blood-based biomarkers, especially when investigating differences between APOE ε4 carriers and non-carriers. Our results also indicate that longer follow-up periods may be required to observe exercise-induced change in blood-based biomarkers.

Objectively-measured movement behaviors, systemic low-grade inflammation, and plasma neurofilament light chain in older adults: a population-based study

BACKGROUND

Evidence has linked self-reported sedentary behavior (SB) and physical activity (PA) with cognitive impairment; however, the underlying mechanisms are poorly understood. We examined the associations of the accelerometer-measured movement behaviors with plasma neurofilament light chain (NfL) among older adults and the role of systemic low-grade inflammation in the associations.

RESULTS

This population-based study included 1,029 dementia-free older adults (age ≥ 60 years, range 60-88 years; 59.48% women) who undertook the ActiGraph substudy (March 2018-December 2020) in MIND-China. There were nonlinear relationships of daily SB and PA time with plasma NfL concentration, such that more daily SB time or less time spent in daily light-intensity physical activity (LPA) and moderate-to-vigorous-intensity physical activity (MVPA) was significantly associated with increased plasma NfL only when SB time ≥ 8.00 h/day or LPA time < 5.00 h/day or MVPA time < 2.00 h/day. Furthermore, more daily SB time or less daily LPA and MVPA time was significantly associated with higher serum low-grade inflammation score, a composite measure generated from serum IL-6, IL-8, TNF-α, and ICAM-1 (P < 0.05). Finally, low-grade inflammation score accounted for 14.5% to 17.8% of the associations between movement behaviors and plasma NfL.

CONCLUSIONS

More daily SB and less PA time are associated with neurodegeneration and systemic low-grade inflammation in older adults. The association of movement behaviors with neurodegeneration is partially mediated by low-grade inflammation.

Association of physical activity with dementia and cognitive decline in UK Biobank

INTRODUCTION

There is a lack of studies on the association between specific physical activity (PA) types and dementia. We examined the association of leisure time physical activity (LTPA), occupational physical activity (OPA), and sedentary lifestyle with dementia risk and cognitive decline using the UK-Biobank study.

METHODS

Baseline PA was collected using questionnaires. A total of 502,481 dementia-free participants were recruited in 2006-2010 and followed for 10 years until the end of 2020 for the ascertainment of dementia. Associations of PA with incident dementia and cognitive decline were examined.

RESULTS

Higher levels of LTPA and OPA and lower levels of sedentary hours were associated with lower dementia risk. The fifth quintiles of LTPA (hazard ratio [HR] = 0.53, 95% confidence interval [CI]: 0.43-0.67) and OPA (HR = 0.68, 95% CI:0.51-0.90) had lower dementia risk, whereas the fifth quintile of sedentary lifestyle had higher dementia risk (HR = 1.23, 95% CI:1.08-1.41).

DISCUSSION

Our findings suggest the promotion of an active lifestyle suggested to be preventive of dementia risk. This research has been conducted using the UK Biobank Resource under Application Number 71022.

Active Gains in brain Using Exercise During Aging (AGUEDA): protocol for a randomized controlled trial

Alzheimer's disease is currently the leading cause of dementia and one of the most expensive, lethal and severe diseases worldwide. Age-related decline in executive function is widespread and plays a key role in subsequent dementia risk. Physical exercise has been proposed as one of the leading non-pharmaceutical approaches to improve executive function and ameliorate cognitive decline. This single-site, two-arm, single-blinded, randomized controlled trial (RCT) will include 90 cognitively normal older adults, aged 65-80 years old. Participants will be randomized to a 24-week resistance exercise program (3 sessions/week, 60 min/session, n = 45), or a wait-list control group (n = 45) which will be asked to maintain their usual lifestyle. All study outcomes will be assessed at baseline and at 24-weeks after the exercise program, with a subset of selected outcomes assessed at 12-weeks. The primary outcome will be indicated by the change in an executive function composite score assessed with a comprehensive neuropsychological battery and the National Institutes of Health Toolbox Cognition Battery. Secondary outcomes will include changes in brain structure and function and amyloid deposition, other cognitive outcomes, and changes in molecular biomarkers assessed in blood, saliva, and fecal samples, physical function, muscular strength, body composition, mental health, and psychosocial parameters. We expect that the resistance exercise program will have positive effects on executive function and related brain structure and function, and will help to understand the molecular, structural, functional, and psychosocial mechanisms involved.

Association between walking and square dancing-oriented leisure-time physical activity and cognitive function among middle-aged and elderly people in Southwest China

BACKGROUND

Southwest China is facing a serious aging problem across the country, but the status of cognitive function in middle-aged and elderly people in this region is superior to the national average. This study intends to reveal the leisure-time physical activity (LTPA) pattern in this region and explore whether this pattern is beneficial for cognitive function.

METHODS

The data came from the 2019-2021 baseline survey on cognitive function of a natural population cohort conducted by West China Hospital of Sichuan University. A structured questionnaire was used to investigate the LTPA status of the participants, and the Mini-Mental State Examination was used to evaluate their cognitive function. Then, we used multiple linear regression to analyze the association between LTPA and cognitive level, and further subgroup analysis was carried out according to sex, age and waist-to-hip ratio.

RESULTS

A total of 2697 participants were enrolled, with an average age of 66.19 ± 6.68 years. The average cognitive function score was 27.23 ± 2.72, of which 8.60% indicated mild cognitive impairment. Their median LTPA level was 24.50 MET-hours per week, of which 70.37% reached the activity level recommended by WHO, with the main types being walking (1340 cases, 49.68%), square dancing (270 cases, 10.01%), or walking + square dancing (172 cases, 6.38%). Multiple linear regression showed that cognitive function increased with the amount of LTPA from 11.25 MET-hours/week to 36.40 MET-hours/week (β 0.09 for 11.25 ~ 24.50 MET-hours/week, β 0.38 for 24.50 ~ 36.40 MET-hours/week) but stabilized at more (β 0.39 for ≥36.40 MET-hours/week). The positive association persisted even for those who only walked (β 0.37 for 24.50 ~ 36.40 MET-hours/week, P = 0.008).

CONCLUSIONS

Middle-aged and elderly people in Southwest China hold a relatively high level of LTPA status, and walking and square dancing-oriented LTPA are positively correlated with cognitive function.

Changes in cardiovascular-health blood biomarkers in response to exercise intervention among older adults with cognitive frailty: A scoping review

Introduction: Cardiovascular health contributes significantly to the incidence of cognitive impairment. Prior to conducting exercise-related intervention, it is crucial to explore cardiovascular health blood parameters that have been commonly used as guidance for the purpose of monitoring. Information on the effectiveness of exercise on cardiovascular-related biomarkers is lacking, especially among older adults with cognitive frailty. Therefore, we aimed to review existing evidence on cardiovascular-related blood parameters and their changes following exercise intervention among older adults with cognitive frailty. Methods: A systematic search was conducted on PubMed, Cochrane, and Scopus databases. Related studies involving only human and full text in either English or Malay language were selected. Types of impairment were limited to cognitive impairment, frailty, and cognitive frailty. Studies were restricted to randomized controlled trial and clinical trial design studies. For charting purposes, all variables were extracted and tabulated. Trends in types of parameters studied were explored. Results: A total of 607 articles were screened, and the final 16 were included in this review. Four cardiovascular-related blood parameter categories were extracted: inflammatory, glucose homeostasis, lipid profile, and hemostatic biomarkers. The common parameters monitored were IGF-1 and HbA1c, glucose, and insulin sensitivity in some studies. Out of the nine studies on inflammatory biomarkers, exercise interventions showed a reduction in pro-inflammatory markers, namely, IL-6, TNF-α, IL-15, leptin, and C-reactive protein and an increase in anti-inflammatory markers, namely, IFN-γ and IL-10. Similarly, in all eight studies, glucose homeostasis-related biomarkers had improved with exercise intervention. The lipid profile was tested in five studies, with four studies showing improvements with exercise intervention via a decrease in total cholesterol, triglycerides, and low-density lipoprotein and an increase in high-density lipoprotein. A decrease in pro-inflammatory biomarkers and an increase in anti-inflammatory biomarkers were demonstrated with multicomponent exercise, including aerobic exercise in six studies and aerobic exercise on its own in the remaining two studies. Meanwhile, four out of six studies that yielded improvements in glucose homeostasis biomarkers involved only aerobic exercise and the remaining two studies involved multicomponent with aerobic exercise. Conclusion: The most consistent blood parameters studied were glucose homeostasis and inflammatory biomarkers. These parameters have been shown to improve with multicomponent exercise programs, particularly with the inclusion of aerobic exercise.