Major Depressive Disorder is characterized by major depressive episodes without a history of manic, mixed, or hypomanic episodes. This disorder is two times more likely in adolescent and adult females than in males. In the preadolescent period, this disorder affects boys and girls equally. Major Depressive Disorder causes the person to feel unmotivated, sad, listless, and emotionally drained. Behavioral manifestations may vary from profound psychomotor retardation and withdrawal to agitation and irritability. These symptoms have a profound impact on activities of daily living. A person suffering from this disorder may find it difficult to work, sleep, eat, and function from day to day. Approximately 25% of the cases include a "presumed" precipitating factor. It appears that there is a precipitant in 50% of the elderly population. Delusions are often mood congruent, and hallucinations are rare and when present are usually paranoid or self-deprecating in nature.

Classical psychoanalytic theory postulates that depressed patients have suffered a real or imagined loss of an ambivalently loved object. The person reacts with rage that is turned inward. Cognitive theory postulates a cognitive triad of distorted perceptions. This theory holds that a person's negative interpretation of his/or her own life causes self-deprecating thought that lead to depression. Biological theories focus on several neurotransmitters, particularly norepinephrine and serotonin. It is suggested that lower levels of one or more of these neurotransmitters causes depression. Some of the evidence for these theories comes from the action of antidepressants; they increase levels of neurotransmitters and thereby reduce depressive symptoms, hence it must be lower levels of these chemicals that "creates" the depression. While some tests that measure neurotransmitter levels show lowered presence in depressed patients, the results are inconsistent.

Assessment should include both psychosocial and medical. You will need to conduct an assessment and address any safety issues with your patient. Establishing a good therapeutic rapport and relieving immediate symptoms is imperative. Supportive psychotherapy is imperative. Warm and empathic understanding can go a long way to improving functioning quickly.

During the clinical interview or assessment, you might use the BDI-II to measure the severity of the patient's depression. The assessment should include suicide and homicide risks. If suicidality is present, you should discuss the plan or means of suicide and take necessary action. A referral to a physician is a good idea to rule out any possible general medical condition that may pre-exist (obtain a release).

A referral to a physician will be necessary also to obtain an antidepressant medication evaluation. Finally, explain the diagnosis and treatment suggestions to the patient. Make sure you are supportive and non judgmental to relieve some of the patient's immediate symptoms. Find out what type of support the patient has and elicit community resources.