Fig. 2

Restricted cubic spline for testing the hypothesis of nonlinear correlation between A Alzheimer’s dementia, B vascular dementia, C frontotemporal dementia, and DII. Spline curves represent hazard ratios (HRs) adjusted for age, sex, ethnicity, education, and Townsend deprivation index, diabetes, blood pressure status, drinking status, smoking status, body mass index, physical activity, energy intake, and family history of dementia. The solid lines are fitted based on Cox-proportional hazard models. The shaded areas show 95% confidential intervals (CIs). The red dashed line indicates the position where the curve inflection point occurs