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.Peer reviewe

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.Peer reviewe

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

Introduction. Physical activity is associated with a decreased occurrence of dementia. In twins, we investigated the effect of persistent physical activity in adulthood on mortality due to dementia. Materials and methods. Physical activity was queried in 1975 and 1981 from the members of the older Finnish Twin Cohort (n = 2 1,791), who were aged 24-60 years at the end of 1981. The subjects were divided into three categories according to the persistence of their vigorous physical activity. Dementia deaths were followed up to the end of 2011. Results. During the 29-year follow-up, 353 subjects died of dementia. In individual-based analyses the age-and sex-adjusted hazard ratio (HR) was 0.65 (95% CI 0.43-0.98) for subjects partaking in vigorous physical activities in both 1975 and 1981 compared to those who were inactive in both years. No significant change was observed after adjusting for potential confounding factors. The corresponding HR for within-pair comparisons of the less active twin versus the more active co-twin was 0.48 (95% CI 0.17-1.32). The results for analyses of the volume of physical activity were inconclusive. Conclusions. Persistent vigorous leisure-time physical activity protects from dementia, and the effect appears to remain after taking into account childhood environment.Peer reviewe

Objectively measured physical activity profile and cognition in Finnish elderly twins

Introduction We studied whether objectively measured physical activity (PA) and sedentary behavior (SB) are associated with cognition in Finnish elderly twins. Methods This cross-sectional study comprised twins born in Finland from 1940 to 1944 in the Older Finnish Twin Cohort (mean age, 72.9 years; 726 persons). From 2014 to 2016, cognition was assessed with a validated telephonic interview, whereas PA was measured with a waist-worn accelerometer. Results In between-family models, SB and light physical activity had significant linear associations with cognition after adjusting for age, sex, wearing time, education level, body mass index, and living condition (SB: β-estimate, −0.21 [95% confidence intervals, −0.42 to −0.003]; light physical activity: β-estimate, 0.30 [95% confidence intervals, 0.02–0.58]). In within-family models, there were no significant linear associations between objectively measured PA and cognition. Discussion Objectively measured light physical activity and SB are associated with cognition in Finnish twins in their seventies, but the associations were attributable to genetic and environmental selection.Peer reviewe

Chronic diseases and objectively monitored physical activity profile among aged individuals - a cross-sectional twin cohort study

Introduction: High physical activity (PA) at old age indicates good functional capacity enabling independent living. We investigated how different disease conditions are associated with measured PA indicators in old women and men, and whether they recognize this association. Materials and methods: This cross-sectional twin cohort study in Finland comprised 779 individuals (276 complete twin pairs, including 117 monozygotic pairs), who participated in hip-worn accelerometer monitoring of PA and responded to questions on diseases and mobility limitations at mean age of 73 (range 71-75). Results: Of the participants, 23.2% reported having a disease restricting mobility. With sex and age in the regression model, the reported disease restricting mobility explained 11.8% of the variation in moderate-to-vigorous PA (MVPA) and 10.4% of the variation in daily steps. Adding stepwise other self-reported diseases and body mass index to the model increased the explanatory power for MVPA up to 18.5% and 25.5%, and for daily steps up to 16.0% and 20.7%, respectively. In the co-twin control analysis the PA differences were smaller in disease-discordant monozygotic than dizygotic pairs. Conclusions: Chronic disease conditions are associated with low PA, which individuals may not always recognize. Shared genetic factors may explain part of the associations.Key messages Among community-dwelling older men and women one-fourth of the variation in objectively measured moderate-to-vigorous physical activity is accounted for by age, sex, body mass index and self-reported diseases. Occurrence of chronic diseases is associated with low physical activity and individuals do not always recognize this. Healthcare professionals should pay attention to the low physical activity and mobility of individuals with chronic disease conditions before these result in limitations in independent living.Peer reviewe

Long-term leisure-time physical activity and other health habits as predictors of objectively monitored late-life physical activity - A 40-year twin study

Moderate-to-vigorous physical activity (MVPA) in old age is an important indicator of good health and functional capacity enabling independent living. In our prospective twin cohort study with 616 individuals we investigated whether long-term physical activity assessed three times, in 1975, 1982 and 1990 (mean age 48 years in 1990), and other self-reported health habits predict objectively measured MVPA measured with a hip-worn triaxial accelerometer (at least 10 hours per day for at least 4 days) 25 years later (mean age of 73 years). Low leisure-time physical activity at younger age, higher relative weight, smoking, low socioeconomic status, and health problems predicted low MVPA in old age in individual-based analyses (altogether explaining 20.3% of the variation in MVPA). However, quantitative trait modeling indicated that shared genetic factors explained 82% of the correlation between baseline and follow-up physical activity. Pairwise analyses within monozygotic twin pairs showed that only baseline smoking was a statistically significant predictor of later-life MVPA. The results imply that younger-age physical activity is associated with later-life MVPA, but shared genetic factors underlies this association. Of the other predictors mid-life smoking predicted less physical activity at older age independent of genetic factors.Peer reviewe

Polygenic Risk Scores and Physical Activity

Purpose Polygenic risk scores (PRS) summarize genome-wide genotype data into a single variable that produces an individual-level risk score for genetic liability. PRS has been used for prediction of chronic diseases and some risk factors. As PRS has been studied less for physical activity (PA), we constructed PRS for PA and studied how much variation in PA can be explained by this PRS in independent population samples. Methods We calculated PRS for self-reported and objectively measured PA using UK Biobank genome-wide association study summary statistics, and analyzed how much of the variation in self-reported (MET-hours per day) and measured (steps and moderate-to-vigorous PA minutes per day) PA could be accounted for by the PRS in the Finnish Twin Cohorts (FTC;N= 759-11,528) and the Northern Finland Birth Cohort 1966 (NFBC1966;N= 3263-4061). Objective measurement of PA was done with wrist-worn accelerometer in UK Biobank and NFBC1966 studies, and with hip-worn accelerometer in the FTC. Results The PRS accounted from 0.07% to 1.44% of the variation (R-2) in the self-reported and objectively measured PA volumes (Pvalue range = 0.023 toPeer reviewe

A 16-yr Follow-up of the European Randomized study of Screening for Prostate Cancer

Background: The European Randomized study of Screening for Prostate Cancer (ERSPC) has previously demonstrated that prostate-specific antigen (PSA) screening decreases prostate cancer (PCa) mortality. Objective: To determine whether PSA screening decreases PCa mortality for up to 16 yr and to assess results following adjustment for nonparticipation and the number of screening rounds attended. Design, setting, and participants: This multicentre population-based randomised screening trial was conducted in eight European countries. Report includes 182 160 men, followed up until 2014 (maximum of 16 yr), with a predefined core age group of 162 389 men (55-69 yr), selected from population registry. Outcome measurements and statistical analysis: The outcome was PCa mortality, also assessed with adjustment for nonparticipation and the number of screening rounds attended. Results and limitations: The rate ratio of PCa mortality was 0.80 (95% confidence interval [CI] 0.72-0.89, p 20 ng/ml (9.9% compared with 4.1% in the second round, p <0.001) and higher PCa mortality (hazard ratio = 1.86, p <0.001) than those detected subsequently. Conclusions: Findings corroborate earlier results that PSA screening significantly reduces PCa mortality, showing larger absolute benefit with longer follow-up and a reduction in excess incidence. Repeated screening may be important to reduce PCa mortality on a population level. Patient summary: In this report, we looked at the outcomes from prostate cancer in a large European population. We found that repeated screening reduces the risk of dying from prostate cancer. (C) 2019 Published by Elsevier B.V. on behalf of European Association of Urology.Peer reviewe

Chronic diseases and objectively monitored physical activity profile among aged individuals – a cross-sectional twin cohort study

Introduction: High physical activity (PA) at old age indicates good functional capacity enabling independent living. We investigated how different disease conditions are associated with measured PA indicators in old women and men, and whether they recognize this association.Materials and methods: This cross-sectional twin cohort study in Finland comprised 779 individuals (276 complete twin pairs, including 117 monozygotic pairs), who participated in hip-worn accelerometer monitoring of PA and responded to questions on diseases and mobility limitations at mean age of 73 (range 71–75).Results: Of the participants, 23.2% reported having a disease restricting mobility. With sex and age in the regression model, the reported disease restricting mobility explained 11.8% of the variation in moderate-to-vigorous PA (MVPA) and 10.4% of the variation in daily steps. Adding stepwise other self-reported diseases and body mass index to the model increased the explanatory power for MVPA up to 18.5% and 25.5%, and for daily steps up to 16.0% and 20.7%, respectively. In the co-twin control analysis the PA differences were smaller in disease-discordant monozygotic than dizygotic pairs.Conclusions: Chronic disease conditions are associated with low PA, which individuals may not always recognize. Shared genetic factors may explain part of the associations.</p

Objectively measured physical activity profile and cognition in Finnish elderly twins

Introduction: We studied whether objectively measured physical activity (PA) and sedentary behavior (SB) are associated with cognition in Finnish elderly twins.Methods: This cross-sectional study comprised twins born in Finland from 1940 to 1944 in the Older Finnish Twin Cohort (mean age, 72.9 years; 726 persons). From 2014 to 2016, cognition was assessed with a validated telephonic interview, whereas PA was measured with a waist-worn accelerometer.Results: In between-family models, SB and light physical activity had significant linear associations with cognition after adjusting for age, sex, wearing time, education level, body mass index, and living condition (SB: β-estimate, −0.21 [95% confidence intervals, −0.42 to −0.003]; light physical activity: β-estimate, 0.30 [95% confidence intervals, 0.02–0.58]). In within-family models, there were no significant linear associations between objectively measured PA and cognition.Discussion: Objectively measured light physical activity and SB are associated with cognition in Finnish twins in their seventies, but the associations were attributable to genetic and environmental selection.</p