A PET scan shows the contrast between the amount of brain activity when a patient is depressed versus when the patient is recovered. Types of behaviors that involve disturbances in emotions and feelings that interfere with daily life are called mood disorders.
Depression is one of the more common of the mood disorders.
Many people, at some point in their lives have experienced some form of depression, caused by such stressful events such as the death of a loved one or other personal problems. Affecting some 10 to 20 percent of the population at any time, depression is a major problem in our society. Depression can sometimes get to be so severe that it may drive people to suicide. Mania is on the other end of the spectrum of mood disorders when compared to depression. Whereas depression involves a state of dejection, mania involves a state of elation and euphoria.