General health checks and incident dementia: A six-year follow-up study of community-dwelling older adults in Japan.

General health checks to detect cardiovascular risk factors form part of routine health care in many countries. Cardiovascular disease and dementia share a number of risk factors; however it remains unclear whether general health checks can reduce the incidence of dementia. We used longitudinal data from the Japan Gerontological Evaluation Study with up to 6.4 years follow-up (from 2010 to 2016). A total of 31,012 disability-free adults aged 65-74 were included. The outcome variable was dementia onset certified under the national long-term care insurance system. The treatment variable was defined as having health checks within the past 12 months prior to the baseline survey in 2010. After multiple imputation, we performed propensity score matching (PSM) to exclude off-support individuals who were the least likely to have health checks. We also performed inverse probability treatment weighting (IPTW) to estimate the effect of the treatment if everyone within the population was compliant to health checks. The hazard ratios for dementia onset among those reporting health checks within the previous year was 0.89 (95% confidence interval (CI): 0.78, 1.02) in the PSM analysis and 0.84 (95% CI: 0.75, 0.95) in the IPTW analysis. We then estimated the effect of health checks on 5-year incident dementia. The 5-year cumulative incidence difference based on the PSM analysis was -0.0046 (95%CI: -0.0101, 0.0009), while that based on the IPTW analysis was -0.0046 (95%CI, -0.0090, -0.0002). The PSM and IPTW approaches yielded similar findings that the incidence of dementia was lower among people having health checks.