It occurs at any age, even in children and young people. Bipolar affective disorder is less common affecting one person in 100 and affects both men and women. There are a number of reasons why people become depressed. Early experiences in life and losses through bereavement or the break-up of a relationship may trigger episodes of depression, and perhaps mania. A number of physical illnesses are also linked with depression, such as infections like influenza, and disorders of the thyroid gland.
Family studies suggest that manic depression in particular sometimes runs in families.
There may be an abnormality in brain biochemistry involving a chemical messenger called serotonin. In a mild episode of depression a person may find that, with support from family or friends, the symptoms improve by themselves. Talking through problems can help resolve any life stresses that may have caused the illness. If the symptoms persist for more than two weeks, people may need to seek professional advice, initially from their family doctor. There are a number of ways of treating depression.