[Epidemiology of headache].

We discuss here the epidemiology of chronic headache. Headache is a widespread and costly public health problem. Few people do not experience headache: in men, the lifetime prevalence for headache of any kind is 93 %, and for women it is up to 99%. Approximately 8.4 million people in Japan suffer from migraine, and 22 million have tension-type headache. Despite the painful, costly, and disabling impact of headache, many patients with headache do not seek medical advice. It is important to recognize the incidence of various kinds of chronic headache, and to diagnose and treat them correctly. In this article, we review the incidence, precipitating factors, regional prevalence, and age dependence of the incidence of each type of chronic headache.