Depression is a common psychiatric disease with pathologically depressed mood and characteristic somatic and sleep disturbance. It is divided into those forms due to external factors, and those where depression arises without obvious cause, including manic-depressive illness. Antidepressants and psychotherapy are among the treatments used.
An antidepressant is a drug used in the treatment of depression. There are two types: tricyclic compounds and monoamine oxidase inhibitors. Although their mode of action is obscure, they have revolutionized the treatment of depression. The effect contrasts with that of depressants.
A depressant is an agent that depresses any organ but specifically the functioning of the central nervous system. Reduction of the level of consciousness and impaired control of breathing are serious effects, usually seen in overdosage. Many drugs including alcohol, barbiturates, and sedatives are depressants. The loss of inhibition associated with their use may be due to a differential depressant effect.