[Bipolar disorder with late onset: an organic variety of mood disorder?].

Bipolar disorder (BD) is commonly associated with late adolescence or early adulthood, although a substantial proportion of patients develops the condition in later life. The results of early clinical investigations suggested that cases of bipolar disorder with onset in later life were more often associated with 'organic causes', and could potentially justify the distinction between early and late onset bipolar disorder. This paper reviews currently available evidence in support of the organic hypothesis for late onset bipolar disorder. It concludes that the split of bipolar disorder according to age at onset is artificial, and lacks clinical significance and epidemiological support.