Comorbidities are a feature of migraine and are explored in this slide deck.
References used on slide:
Feinstein AR. The pre-therapeutic classification of co-morbidity in chronic disease. J Chronic Dis 1970; 23 (7): 455–468.
Wang SJ, Chen PK, Fuh JL. Comorbidities of migraine. Front Neurol 2010; 1: 16.
Westreich D. Berkson’s bias, selection bias, and missing data. Epidemiology 2012; 23 (1): 159–164.v