Among the limitations of this study is the observational design of the BLSA and most studies included in the meta-analyses. The BLSA is also not a representative sample of the US population. However, as the meta-analysis supports, the BLSA results were similar to those obtained in other samples, and we found no evidence of heterogeneity in the published studies. The number of studies that measured the five factors is still relatively small, but for neuroticism the meta-analysis included a total 5054 individuals, with 607 cases of incident AD. Additional studies are needed to increase these numbers and to test the potential mechanisms underlying the association between personality traits and incident AD. Given the strength of the association between personality traits and risk of AD, the consistency of these associations across the published studies, and the clinical value of identifying factors that may promote resilience to AD neuropathology,50 personality traits should be further evaluated as important risk factors of AD.
