In Mood disorders the fundamental disturbances is a change in mood or affect, usually to depression (with or without anxiety) or to elation (mania or hypomania). This mood change is normally accompanied by a change in the overall of activity, and most of the symptoms are either secondary to, or easily understood in the context of, such changes. Most of the disorders tend to be recurrent, and the onset of individual episodes is often related to stressful events or situations.
The term “mania” and “severe depression” are used to denote the opposite ends of affective spectrum; “hypomania” is used to denote an intermediate state without delusion, hallucinations, or complete disruption of normal activities, which is often (but not exclusively) seen as patients develop or recovery from mania.
There degrees of severity are specified here (hypomania, mania with and without psychotic symptoms) sharing the common underlying characteristics of elevated mood, and an increase in the quantity speed of physical activity. All the subdivisions of this category should be used only for a single mania episode.
In typical depressive episode in all three levels (mild, moderate and severe), the individual usually suffers from depressed mood, loss of interest, and enjoyment, and reduced energy leading to increased fatigability and diminished activity. Marker tiredness after only slight effort is common.
If previous or subsequent affective episodes (depression, mania or hypomania), the disorder should be coded under bipolar affective disorder.