The potential association between obesity and bipolar disorder: A meta-analysis

Background Several epidemiological studies have found that the prevalence of bipolar disorder (BD) is significantly higher in obese population than non-obese population. However, no meta-analysis has been published to quantitatively summarize the related literature. Methods In this study, we conducted a meta-analysis to explore the association between obesity and BD by combining 9 cross-sectional studies with a total of 12,259 BD cases and 615,490 non-BD controls. The meta-analysis was performed using the effect estimates and 95% confidence intervals (CIs) to calculate the pooled odds ratio (OR), while the heterogeneity was assessed using I² and Q statistic. Results Our meta-analysis suggests that obesity is associated with increased prevalence of BD by a random-effect model (OR=1.77, 95% CI: 1.40–2.23; Q=44.62, P<0.001, I²=82.1%). Limitation Without prospective studies, we cannot determine whether obesity increased the risk of developing BD or vice-versa. Conclusion Obesity is positively associated with BD.