Feelings of sadness, hopelessness, and a loss of interest in life, combined with a sense of reduced emotional well being. Most people experience these feelings occasionally, usually as a normal response to an upsetting event; for example, it is natural to feel depressed when a close relative dies. When a person’s behavior and physical state are also affected, however, this is an indication that the symptom is part of a depressive illness.
Depression that occurs without any apparent cause, deepens, and persists may occur as part of a variety of psychiatric illnesses. Some people who suffer from depression are eventually diagnosed as having manic depressive illness (also known as bipolar affective disorder) a condition characterized by episodes of depression alternating with mania (periods of overly excitable mood and uncontrolled behavior).
Symptoms vary with severity of the condition. In a person suffering from mild depression, the main symptoms are anxiety and a variable mood; the person may also have fits of crying that occur for no apparent reason. More severe depression may cause loss of appetite, difficulty in sleeping, tiredness, loss of interest in social activities, and impaired concentration. Movement and thinking become slower; alternatively, the opposite occurs, and the person may become extremely anxious. Severely depressed people may have thoughts of committing suicide and feelings of worthlessness. Hallucinations or delusions may occur in extreme cases.
Often, there is no single obvious cause, and a combination of factors may be involved. Depression may be triggered by physical illnesses (such as a viral infection), by hormonal disorders (such as hypothyroidism), or by the hormonal changes that occur following childbirth (postnatal depression). Certain drugs, such as oral contraceptives, may contribute to the condition. Inheritance may play a part in manic depressive illness. Some people become depressed in the winter, probably in response to the long hours of darkness. Aside from these causes, there are social and psychological factors that may play a role. Depression may also be related to the number of disturbing changes or events in a person’s life.
Depression is the most common serious psychiatric illness. The World Health Organization ranks it fourth in the ten leading causes of disease worldwide. One person in six is estimated to suffer some degree of depression in their life time, and one person in 20 develops clinical depressive illness. Depression is particularly common in people over 50, and appears to be more common in women; twice as many women as men seek help for the condition. This difference may result from the fact that women are more prepared to seek help for their symptoms, while men may be more likely to express their discontent in the form of problems such as alcohol abuse and violence.
Depression is often a recurrent disorder, up to three quarters of people who have needed hospital treatment for depression will have another episode within 10 years. However, long term antidepressant medication and psychological therapies can greatly reduce the risk of recurrence. Despite the effectiveness of drug treatment, suicide remains a serious risk; nearly half of all deaths in people with recurrent depression are due to suicide. This risk can, however be substantially reduced by maintenance treatment with anti depressive drugs.