Polycystic ovary syndrome, personality, and depression: A twin study

Background: Women with polycystic ovary syndrome (PCOS) are at elevated risk for suffering from depression. Neuroticism is a personality trait that has been associated with an increased risk for developing major depressive disorder (MDD). The aim of the present study was to quantify and decompose the correlation between neuroticism, PCOS, and MDD into shared and unique genetic and environmental etiologies, by using quantitative genetic methods. Methods: In a cohort of 12,628 Swedish female twins born from 1959 to 1985, neuroticism, PCOS identified by symptoms of hyperandrogenemia (i.e., hirsutism) and oligo- and/or anovulation, and lifetime MDD status were determined through questionnaire responses. Structural equation modeling was used to study the genetic and environmental sources of the variation within, and covariation between neuroticism, PCOS, and MDD. Results: Female twins with PCOS (n = 752) had significantly higher levels of neuroticism than women without PCOS, and a 2-fold increase in odds for a lifetime prevalence of MDD. The phenotypic correlation between PCOS and MDD was 0.19, with 63% of the correlation attributable to common genetic factors between the two traits. When taking into account neuroticism, 41% was attributable to common genetic factors and 9% attributable to common environmental factors shared between all three traits, with the remainder attributable to components unique to PCOS and MDD. Conclusion: There are common genetic factors between neuroticism, PCOS, and MDD; however, neuroticism shares approximately half of the genetic and environmental components behind the phenotypic correlation between PCOS and MDD, providing some etiological evidence behind the comorbidity between PCOS and depression.