Twenty-year trends in cognitive performance and modifiable dementia risk factors: a Swiss population-based study

Population trends in cognitive performance have been mixed, and few studies included data following the COVID-19 pandemic. We examined 20-year cognitive performance trends, and the contribution of modifiable dementia risk factors. We used repeated cross-sectional survey data from 2005 to 2025. Adults aged 50 to 75 years completed the clock drawing test (N = 6902, 51% women). We calculated the updated LIfestyle for BRAin health (LIBRA2) index. Analyses used linear regression models. Cognitive performance declined over time [β (95% CI), -0.11 (-0.14 to -0.09), P <.001]. Higher LIBRA2 scores were associated with poorer cognitive performance [-0.08 (-0.11 to -0.05), <.001]. The decline in cognitive performance remained significant after adjustment for the LIBRA2 and its components. There was a small but significant decline in cognitive performance between 2005 and 2025. Well-known dementia risk factors did not fully explain the decline. Further research is needed to identify contributing factors, including the impact of digitalisation on society.