The mood disorders are pervasive and sustained inner emotions that affect the person’s perception of the world. In addition to being part of the conscious experience of the person, it can be observed by others. In healthy people, moods can be normal, elated, or depressed, and people generally feel that they have some degree of control of their moods. That sense of control is lost, however, in the mood disorders, which include depressive disorders and bipolar disorders. Along with schizophrenia, the mood disorders form the major psychiatric illnesses today.
In the depressive disorders (depression), the prominent features are a pervasive sadness; a loss of energy, interest, or pleasure; anxiety; irritability; disturbed sleep; and thoughts of death or suicide. Depression can occur on its own, independent of any other illness, or it can arise secondary to other medical disorders. It is associated with decreased neuronal activity and metabolism in the anterior part of the limbic system and nearby prefrontal cortex. These same brain regions show abnormalities, albeit inconsistent ones, in bipolar disorders. The term bipolar disorders describes swings between mania and depression. Episodes of mania are characterized by an abnormally and persistently elated mood, sometimes with euphoria (that is, an exaggerated sense of well-being), racing thoughts, excessive energy, overconfidence, and irritability.