ABSTRACT
Major depressive disorder is characterized by sadness, fatigue, physical symptoms, sleep and psychomotor disturbances, reduced drive, poor appetite and concentration, feelings of worthlessness and self-blame, and thoughts of death. The monoamine hypothesis proposes that depressive illness results from a deficit in monoamine neurons. In bipolar disorder the individual swings between extremes of serious depression and mania. The characteristic symptom of major depression is persistent, often extreme, sadness (depressed mood). Both cognitive and neurochemical factors are involved in depressive illness. The monoamine hypothesis of affective disorders proposes that depressive illness results from a deficit in neurons using the monoamines norepinephrine and serotonin as transmitters. In the bipolar disorders the individual swings between extremes of serious depression and mania. The most effective treatment for bipolar illness, lithium salts, has a rapid effect when administered in the manic phase, and also prevents the next swing to depression.
