Association between sedentary behavior and dementia: a systematic review and meta-analysis of cohort studies

Objective This study aimed to assess the association between sedentary behavior (SB) and dementia among the general adult population. Methods We queried PubMed, Web of Science, Embase, and Cochrane Library from their inception to November 3, 2024. Two authors independently extracted the data from included studies, including hazard ratios (HRs) and their 95% confidence intervals (CIs), to assess the risk of dementia among individuals with SB. The quality of included studies was assessed using the Newcastle-Ottawa Scale. We used a random effects model if I2 > 50% and p < 0.10; otherwise, a fixed-effect model was used. In addition, we assessed publication bias by funnel plot, and performed leave-one-out sensitivity analysis. Results We included ten cohort studies, nine of which were of high quality. Our analysis demonstrated an increased risk of dementia among individuals with SB (pooled HRs, 1.17; 95% CIs, 1.06-1.29). Individuals with high sedentary time (ST), defined by TV viewing, demonstrated a 31% increased risk of dementia compared to those with low ST (pooled HRs, 1.31; 95% CIs, 1.25-1.37). No significantly increased risk for dementia was observed among individuals with high computer usage time (pooled HRs, 0.89; 95% CIs, 0.73-1.09). However, when SB was defined by other methods, individuals with high ST demonstrated a 33% increased risk of dementia compared to those with low ST (pooled HRs, 1.33; 95% CIs, 1.25-1.42). Conclusion SB increases the risk of dementia, but SB defined by computer usage time has not shown this association. Trial registration CRD42023493109.