Depression (psychology), mental disorder characterised by feelings of worthlessness, guilt, sadness, helplessness, and hopelessness. In contrast to normal sadness, or the grief accompanying the loss of a loved one, clinical depression is sadness without any apparent reason and is persistent and severe. It may be accompanied by a variety of related symptoms, including disturbances in sleep and eating, loss of initiative, self-punishment, withdrawal and inactivity, loss of pleasurable feelings, and impotence.
In Britain, 10 per cent of people suffer from some form of depression during their lifetimes and surveys suggest that 20 per cent of people in the United States suffer from significant depressive symptoms at any one time, with perhaps some 25 per cent of the population suffering from a period of depression at some point in their lives. The disorder strikes men and women of all ages and from all parts of society, but some studies indicate that women are more often afflicted.
In psychiatry, two major forms of depressive disorders are recognised. In both, the predominant symptom is a disturbance in mood. One form, depressive disorder, is marked only by episodes of depression. The other form, manic (bipolar) depressive illness, is characterised by alternating depressed and manic episodes.
In both forms a depressed mood predominates-although the patient may not be aware of feeling sad. Typically, sufferers lose all interest in and withdraw from usual activities. Symptoms may include sleep disturbances (usually early-morning awakening); loss of appetite or greatly increased appetite; inability to concentrate or to make decisions; slowed thinking and decreased energy; feelings of worthlessness, guilt, hopelessness, and helplessness; diminished sexual interest; and recurrent thoughts of suicide and death, sometimes leading to suicide.
In the manic phase of bipolar illness, the patient's mood can be elevated, expansive, or irritable. Behaviour is bizarre and sometimes obnoxious. Other symptoms may include excessive talkativeness, thoughts that leap from one point or subject to another, and grandiose ideas; greatly increased social, sexual, and work activity; distractibility; loss of judgement; and a decreased need for sleep.
Certain research findings suggest that a predisposition to these depressive disorders is genetically transmitted, as the risk of a depressive disorder is greater in the families of depressive patients than in the population at large. Studies have suggested that this genetic predisposition may be linked with an abnormal sensitivity to the neurotransmitter acetylcholine in the brain. Receptors for acetylcholine have been found to occur in excessive numbers in the skin of a number of patients suffering from depressive disorders.
The apparent higher proportion of depression in women may be because women with problems are more likely to seek help than men; statistics reporting a higher incidence of depression among women than among men may be explained, at least in part, by an underdiagnosis of depression in men. Alternatively, it may be that some women are still learning social roles that favour feelings of excessive passivity.
Depressive disorders are, thankfully, among the most treatable in psychiatry. They have been linked with the dysfunction of three major neurotransmitter systems (involving serotonin, dopamine, and noradrenaline) in the brain. Three major classes of drugs are used to treat depressive disorders: the tricyclic/tetracyclic antidepressants; the monoamine oxidase (MAO) inhibitors, which prevent the breakdown of monoamine transmitters; and the 5HT reuptake inhibitors.
The tricyclics act by blocking the reuptake of serotonin and noradrenaline into the neurons, prolonging the effects of these transmitters. The tetracyclics require following a special diet because they interact with tryamine, which is found in cheeses, beer, wine, chicken livers, and other foods, and causes elevation of blood pressure. (The tricyclic antidepressants require no special diet but may have a toxic effect on cardiac tissue.)
A recently launched class of effective antidepressants, called 5HT reuptake inhibitors, acts by blocking the reuptake of both serotonin and nonadrenaline in the brain and is said to have fewer side-effects. These drugs have shown potential efficacy in treating many kinds of depression and include venlafaxine (Efexor) and fluoxetine (Prozac), which inhibits the reuptake of 5HT or 5HT and noradrenaline in the brain. Introduced in 1986, Prozac had been prescribed to more than 10 million people worldwide by 1994. Lithium carbonate, a common mineral, is used to control the manic phase of manic-depressive illness, although its action is not clearly understood. In smaller doses it is also used to regulate the mood fluctuations of this bipolar disorder. Carbamazepine is used in cases not responsive to lithium or lithium carbonate.
Electroconvulsive therapy (ECT) is considered by some practitioners as a last resort for patients with severe depression that is not responsive to drug therapy. Psychotherapy and counselling are other major forms of treatment which may be recommended alongside or instead of prescribed antidepressants.