"The common cold of psychological problems" (Seligman, 1973)

This quotation compares the widespread incidence of depression with that of common colds, but it is a bit misleading - depression is a very serious, sometimes disabling, condition.

Like colds though, depression affects the lives of millions of people every year; about 5-10% of people - these estimates vary, figures could be much higher. Many people suffer depression without seeking help, even though, unlike cold remedies, treatments for depression are often effective.

Depression is a mood, or 'affective' disorder in which a sustained emotional state colours a person's perceptions, thoughts and behaviour.

It is normal to feel depressed from time to time, but clinical depression occurs when depression becomes hard to break out of, lasts a long time and affects a person's ability to function normally.

People can recover from depression and never suffer from it again. Others may experience further episodes of depression, while some people suffer chronic long-term symptoms.

More women than men are diagnosed with depression.

It is difficult to diagnose depression - it often accompanies other types of disorders that must be ruled out.

Diagnosis requires five or more of the following symptoms for at least two weeks:

1. Extreme sadness, tearfulness, depressed mood.
2. Loss of interest in activities normally enjoyed, social withdrawal.
3. Disturbed sleep - loss of sleep (insomnia), or more sleep than normal.
4. Changed activity level: often agitated (or slowed down and lethargic).
5. Disturbed appetite and weight change - may be increased or decreased.
6. Loss of energy and tiredness.
7. Self-reproach, guilt, low self-esteem, anxiety.
8. Difficulty making decisions, diminished concentration-span.
9. Thoughts of death and suicide, suicide attempts.