Inclusion and Exclusion Criteria

The inclusion criteria for the study were as follows: cohort study and RCT design, population-based or community-based samples, reporting data on dementia and mild cognitive decline (MCI) diagnosed using validated criteria, and participants defined aspirin use in any dose and for any duration. Trials assessing the effect of aspirin vs. control (placebo in the RCTs or no intervention in cohort studies) were also included. Results, including odds ratios (ORs), relative risks (RRs), or hazard ratios (HRs) with corresponding 95% confidence intervals (CIs), or indirect data for the calculation of the risk estimates were noted.

The exclusion criteria for the study were as follows: participants who were diagnosed with MCI or dementia at baseline, use of active controls in the control group (non-placebo in the RCTs), studies with insufficient or overlapping data (the most recent and complete data were chosen), and the full text of relevant articles could not be obtained.