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

• Published in: BMJ (Online) 2019-04, Vol.365, p.l1495
• Main Authors: Kivimäki, Mika, Singh-Manoux, Archana, Pentti, Jaana, Sabia, Séverine, Nyberg, Solja T, Alfredsson, Lars, Goldberg, Marcel, Knutsson, Anders, Koskenvuo, Markku, Koskinen, Aki, Kouvonen, Anne, Nordin, Maria, Oksanen, Tuula, Strandberg, Timo, Suominen, Sakari B, Theorell, Töres, Vahtera, Jussi, Väänänen, Ari, Virtanen, Marianna, Westerholm, Peter, Westerlund, Hugo, Zins, Marie, Seshadri, Sudha, Batty, G David, Sipilä, Pyry N, Shipley, Martin J, Lindbohm, Joni V, Ferrie, Jane E, Jokela, Markus
• Format: Article
• Language: English
• Subjects: Alzheimer's disease; association; Cardiovascular disease; cohort; Coronary artery disease; Dementia; Dementia - epidemiology; Dementia - etiology; Dementia disorders; Diabetes mellitus; Electronic medical records; Exercise; follow-up; Health risk assessment; Heart diseases; heart-disease; Humans; Incidence; Individ och samhälle VIDSOC; Individual and Society VIDSOC; job strain; life-style; men; Meta-analysis; Metabolic Syndrome - epidemiology; Metabolic Syndrome - etiology; Mortality; Observational Studies as Topic; Physical activity; proportional-hazards; Risk Factors; Sedentary Behavior; time; United Kingdom - epidemiology
• ISSN: 0959-8138; 1756-1833; 1756-1833
• DOI: 10.1136/bmj.l1495

AbstractObjectiveTo 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.DesignMeta-analysis of 19 prospective observational cohort studies.Data sourcesThe 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 methodThe 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.ResultsStudy 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 before dementia onset 1.30, 0.79 to 2.14).ConclusionsIn analyses that addressed bias due to reverse causatio