3.2 Affective disorders
Affective or mood disorders include manic-depressive illness or bipolar disorder (it is called bipolar because it has ‘two poles’: mania and depression). However, by far the most prevalent affective disorder is major depression (MD), which accounts for 80–95% of all depressions. Major depression is sometimes called unipolar disorder to contrast it with bipolar disorder. In MD the individual suffers depressive symptoms (for example sadness, hopelessness, passivity, sleep and eating disturbances) without ever experiencing mania. In mania, the individual experiences symptoms of extreme elation, expansiveness and irritability, talkativeness, inflated self-esteem, and flight of ideas. DSM-IV-TR distinguishes between two kinds of bipolar disorders, depending on whether the depression has full manic episodes or just ‘hypomanic’ episodes (episodes that are not as severe as full manic episodes). Table 2 lists and provides a brief description of the main affective disorders. Our focus in the rest of this section will be on major depression (MD). Bipolar disorder will not be considered further here.
| Name | Description |
|---|---|
| Major depression (MD), also called major depressive disorder (MDD); unipolar disorder; major depressive episode (MDE); clinical depression | Lowered mood and decreased interest or pleasure in all activities, over a period of at least 2 weeks |
| Dysthymia or dysthymic disorder | Milder than major depression, but has a chronic, ‘smouldering’ course, and seldom disappears spontaneously |
Bipolar disorder (Type I); was called manic-depressive disorder (see also for mania) | Repeated episodes of mania, or mixed episodes of mania and depression, hence also called manic-depressive disorder. Mania is a distinct period of abnormally and persistently elevated, expansive, or irritable mood and impaired judgement |
| Bipolar disorder (Type II) | Characterised by hypomania, a milder form of mania that is not associated with marked impairments in judgements or performance, but associated with major depression |
| Cyclothymia or cyclothymic disorder | Hypomania alternating with periods of depression that are not major, i.e. fewer symptoms and shorter duration |
| Postnatal depression (PND) | Usually, the depression begins during the first year of parenthood, and ranges in severity from mild to severe |
| Seasonal affective disorder (SAD) | Depression is more common in the winter months and in the Northern Hemisphere, which suggests to some researchers that brain chemistry is affected by sunlight exposure |