[Epidemiology of bipolar disorders. Current studies]

The prevalence of bipolar disorder over a lifetime, which is similar to that for one year since this is a chronic disease, is around 1% of the general population. Estimates of incidence vary (0.3 to 3 cases per 10000). This general morbidity corresponds quite closely to that found in institutions, since patients presenting with bipolar disorders are not necessarily in care. Bipolar disorder affects men and women in equal proportions, and independently of ethnic and cultural background or of socio-economic status. It is nevertheless more prevalent in urban than in rural areas, and is more common in subjects who are divorced, separated or have never married than in married subjects who have never divorced. It mainly affects younger subjects, with the mean age of onset being about 20 years. Furthermore, it appears to be more common in subjects born since 1930-1940. Finally, it is often associated with other mental disorders, particularly alcoholism and drug dependence.