A Twin Study of Depression and Migraine: Evidence for a Shared Genetic Vulnerability

OBJECTIVE: To determine if shared genetic or environmental vulnerabilities could underlie depression and migraine. BACKGROUND: Depression and migraine headaches frequently coexist and their comorbidity may be due to shared etiologies. METHODS: Female twins in the University of Washington Twin Registry responded to a mailed survey regarding their health history. Depression and migraine were determined by self-report of a physician's diagnosis. We used bivariate structural equation modeling to test for shared genetic, common environmental, and unique environmental components, and to estimate the magnitude of any shared component. RESULTS: Among 758 monozygotic and 306 dizygotic female pairs, 23% reported depression and 20% reported migraine headaches. Heritability was estimated to be 58% (95% confidence interval: 48-67%) for depression and 44% (95% confidence interval: 32-56%) for migraine. Bivariate structural equation modeling estimated that 20% of the variability in depression and migraine headaches was due to shared genes and 4% was due to shared unique environmental factors. CONCLUSIONS: The comorbidity of depression and migraine headache may be due in part to shared genetic risk factors. Research should focus attention on shared pathways, thereby making progress on 2 disease fronts simultaneously and perhaps providing clinicians with unified treatment strategies.