Depression and manic depression

Different types of depression

At the end of a period of depressive illness most people gradually recover their normal behaviour and, although the illness sometimes recurs, are effectively cured. This type of depression is called unipolar. But about one person in ten with depressive illness finds that when the depression lifts, they overshoot their normal state and enter a period of elation or mania.

This illness manic depression, affects about five people in 1000. Perhaps double this number show manic depressive tendencies. Unlike unipolar depression, manic depression is a psychotic illness and often causes bizarre behaviour.

Reasons for depression

People who have experienced recent adverse or traumatic events such as the loss of a job, bereavement, divorce, loss of money or status, rejection by a loved one or the need to care for small children under difficult circumstances, are at greater risk of becoming depressed. So are those who have experienced rejection in their childhood. Rejection in later life may then re-awaken the childhood feelings and lead to depression.

A variety of physical conditions may also lead to depression including infectious illnesses (such as influenza and glandular fever), medical treatment (such as chemotherapy and radiotherapy) and life-threatening or mutilating surgery. Neurological diseases such as Parkinson's disease, multiple sclerosis, stroke and epilepsy can all produce depression in their sufferers. So can cancer and kidney disease. Poor nutrition through an inadequate diet due to poverty or excessive dieting may also possibly increase the risk.

Women frequently develop depression after having a baby. Between 50 per cent and 80 per cent of mothers develop the 'blues' within a few days of giving birth. It is not usually serious and disappears within days.

True post-natal depression affects 5 per cent to 22 per cent of mothers and usually starts within six weeks of the birth. There is some evidence that social and psychological factors can make you more vulnerable to post-natal depression.

Even apart from post-natal depression, men are less likely than women to develop depressive illness. This may be due in part to changes in hormone levels which women experience during the menstrual cycle, menopause and during pregnancy.