Epidemiology of migraine.

Migraine affects over a billion people worldwide and brings with it a huge burden of disability. It is a disease which disproportionally affects the working age population which heightens its economic impact, both at the individual family level and the societal level. Women are significantly more affected by migraine at every age and in all social and geographical groups. At the most severe end of the spectrum, chronic migraine is associated with poorer overall physical and mental health as well as increased risk of unemployment and lower household income. Estimates of the incidence and prevalence of migraine vary with sex, race, ethnicity, geography, socioeconomic, and educational status, suggesting there are many factors at play. In many cases, it is not clear whether these factors are causative of migraine, the effects of migraine, or (as is most likely) a combination of both. Future studies should aim to clarify these links, so that modifiable factors can be addressed where possible and those at risk of developing chronic migraine might receive targeted treatment at an early stage.