Weight change in people with depression and the risk of dementia: a nationwide cohort study

BackgroundDepression is a risk factor for dementia and weight change can appear as a symptom of depression. However, the association between weight change after the diagnosis of depression and the risk of dementia is poorly established. This study aimed to investigate the association between weight change before and after a diagnosis of depression with the subsequent risk of dementia.MethodsThe National Health Insurance Sharing Service database was used. 1 308 730 patients aged > 40 years diagnosed with depression were identified to be eligible. Weight changes after their depression diagnosis were categorized and subsequent incidence of dementia was followed up.ResultsDuring an average follow-up period of 5.2 years (s.d., 2.0 years), 69 373 subjects were newly diagnosed with all-cause dementia (56 351 were Alzheimer's disease and 6877 were vascular dementia). Regarding all outcomes, compared to those with a minimal weight change (-5 to 5%), all groups with weight gain or loss showed increased risks of dementia after adjusting potential risk factors for dementia, in all analysis models with a dose-response relationship, showing a U-shaped association.ConclusionsWeight change as a symptom of depression could be a predictor for the future development of dementia.