increased by more than 30% (HR = 1.33; 95%CI =1.21–1.45). The association was highly consistent across studies (Q = 2.6; degrees of freedom (df) = 4; p = 0.63), and in this set of studies we observed no statistical evidence of publication bias (Kendall’s z-tau = 1.22; p = 0.22; and Egger‘s regression intercept test: t = 1.87; df = 3; p = 0.16). The meta-analysis also indicated that lower scores on conscientiousness were associated with higher risk of incident AD (HR = 0.77; 95%CI =0.69–0.86; p = 2*10−6); again there was no evidence of heterogeneity (p = 0.55) or publication bias (p > 0.05). By pooling the results from the three studies, we also found significant associations for Openness (HR = 0.86; 95%CI =0.77–0.96; p = 0.008; heterogeneity: p = 0.91; publication bias p > 0.05) and Agreeableness (HR = 0.88; 95%CI =0.79–0.98; p = 0.019; heterogeneity: p = 0.51; publication bias p > 0.05), such that open and agreeable people were at lower risk of AD. There was no significant association with Extraversion (HR = 0.96; 95%CI =0.86–1.07; p = 0.53).
