Personality traits differentiate patients with bipolar disorder and healthy controls – A meta-analytic approach

•Patients with bipolar disorder and healthy controls differed in personality traits of the Three Factor Model/ Five Factor Model.•Bipolar disorder scored significantly higher in Neuroticism and lower in Extraversion and Conscientiousness.•Mean age and gender distribution did not influence effect sizes, except for mean age in Neuroticism.•In older samples difference in Neuroticism was smaller than in younger samples. Expression of specific personality traits has been associated with the presence and disease course of bipolar disorder (BD) in multiple studies. However, until today findings are inconsistent and potentially confounding factors such as age and gender as well as the limited sample size of previous studies make it difficult to generalize these findings. To overcome these limitations and to specify the role of personality traits in the context of BD, we performed a meta-analysis in patients with BD and healthy controls (HC), focusing on the traits of the big three and the big five: Neuroticism (N), Extraversion (E), Openness (O), Conscientiousness (C), Agreeableness (A) and Psychoticism (P). Two online databases (Pubmed and Web of Science) were searched systematically to identify relevant articles, including publications up to December 31, 2019. From studies that met our inclusion criteria (n = 18), we extracted relevant data of patients with BD (n = 1694) and HC (n = 2153) and calculated effect sizes for each personality trait. Further, we performed moderator analysis on gender, age, quality score and years of publication. Our results indicate that patients with BD exhibit higher scores on N (large positive effect size; n = 18, g = 1.44, 95%-CI : 1.11 to 1.77) and lower scores on C (medium negative effect size; n = 6, g = -0.78, 95%-CI: -1.13 to -0.43) and E (small negative effect size; n = 13, g = -0.38, 95%-CI: -0.52 to -0.23) compared to HC. We found a moderating effect of mean age on the effect size of N with smaller differences in N levels between patients with BD and HC in older samples (-0.0437, z = - 3.96, p