Genetic and environmental factors in primary dysmenorrhea and its relationship to anxiety, depression, and neuroticism.

Over 1200 pairs o f female monozygotic and dizygotic twins with regular menses reported on the amount of flow, severity o f pain, and degree of limitation experienced during menstruation. Fifty-two percent o f the women reported moderate or severe menstrual pain and these reports were fairly repeatable (0.62-0.80) over a 3-month interval. Heritabilities were 0.22 for flow, 0.38 for pain, and 0.36 for limitation. Covariations between menstrual symptoms and the symptoms and personality variables o f state anxiety and depression and trait neuroticism were shown to be almost entirely genetic in origin. There was also gene action specifically affecting menstrual pain and also menstrual flow, but genetic variation in limitation was entirely due to genes also affecting flow, pain, and personality variables--neuroticism in particular.