|A chronic depression of mood which does not currently fulfil the criteria for recurrent depressive disorder, mild or moderate severity, in terms of either severity or duration of individual episodes, although the criteria for mild depressive episode may have been fulfilled in the past, particularly at the onset of the disorder. The balance between individual phases of mild depression and intervening periods of comparative normality is very variable. Sufferers usually have periods of days or weeks when they describe themselves as well, but most of the time (often for months at a time) they feel tired and depressed; everything is an effort and nothing is enjoyed. They brood and complain, sleep badly and feel inadequate, but are usually able to cope with the basic demands of everyday life. Dysthymia therefore has much in common with the concepts of depressive neurosis and neurotic depression. If required, age of onset may be specified as early (in late teenage or the twenties) or late.|
The essential feature is a very long-standing depression of mood which is never, or only very rarely, severe enough to fulfil the criteria for recurrent depressive disorder, mild or moderate severity. It usually begins early in adult life and lasts for at least several years, sometimes indefinitely. When the onset is later in life, the disorder is often the aftermath of a discrete depressive episode and associated with bereavement or other obvious stress.