Comorbidity of migraine

Comorbidity refers to the greater than coincidental association of separate conditions in the same individuals. Historically, a number of conditions have been noted to be comorbid with migraine, notably psychiatric disorders (anxiety, depression, panic disorder), epilepsy, asthma, and some congenital heart defects. Migraine sufferers have increased medical costs overall compared with others of the same sex and age, even after considering the cost of specific migraine treatment. Thus, estimates of the burden of migraine often include the costs of conditions comorbid with it.Conditions may be comorbid through a variety of mechanisms. Comorbidity may be an artifact of diagnostic uncertainty when symptom profiles overlap or when diagnosis is not based on objective markers. Comorbidity may arise due to unidirectional causality, such as migraine resulting in blood pressure changes due to headache-specific treatment. Finally, conditions may be comorbid because of shared genetic or other factors that increase the risk of both conditions. In such cases, understanding these shared risk factors may lead to greater understanding of the fundamental mechanisms of migraine.In this article, we will review recent developments related to migraine comorbidity. We will emphasize findings related to the comorbidity of migraine with clinical and sub-clinical vascular brain lesions, congenital heart defects, coronary heart disease, psychiatric illness, and other pain conditions.