Causal effects of physical activity on health outcomes including dementia among older adults: a proposal of a new instrumental variable

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K18931
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 58030:Hygiene and public health-related: excluding laboratory approach
• Research Institution: Kyoto University
• Principal Investigator: Sato Koryu 京都大学, 医学研究科, 助教 (20867965)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 身体活動 / 認知症 / うつ傾向 / 操作変数法 / COVID-19

Outline of Final Research Achievements

By applying causal inference methods (including the instrumental variable method) to a large prospective cohort study, this project revealed the impact of lifestyle (including physical activity) and socio-economic factors on health. Specifically, it showed that physical activity once per week lowers the risk of dementia, suggesting that the causal effect of physical activity on lowering the risk of dementia persists for at least four years.
The study also showed that, in response to the COVID-19 pandemic that occurred during the study period, people who decreased their number of steps or increased their working hours during the emergency declaration period had a higher risk of depression, while those who newly started working from home had a 17% lower risk of depression than the rest of the population.

Free Research Field

社会疫学

Academic Significance and Societal Importance of the Research Achievements

本研究は、積雪地域の居住を高齢者の身体活動の操作変数として用いるというアイデアを新たに提案し、身体活動と認知症リスクの因果関係を明らかにした。また、研究期間中に生じた新型コロナウイルス感染症の流行に対し、日本老年学的評価研究(JAGES)の中で2020年度の臨時調査を行い、2019年度のデータと接続することで思い出しバイアスの少ない質の高いデータを整備した。さらに、パンデミック前後での身体活動やソーシャルキャピタルの変化が、うつ傾向と関連することを示した。