mood disorder

Meaning: A mood disorder is a persistent disturbance in emotional state, beyond normal sadness or elation, that disrupts daily life. The two families are depressive disorders (major depressive disorder, persistent depressive disorder) and bipolar and related disorders (bipolar I, bipolar II, cyclothymic disorder). A major depressive episode involves depressed mood or loss of interest, usually with changes in sleep, appetite, energy, concentration and self-worth, lasting at least two weeks. A manic episode is a distinct period, lasting at least a week, of elevated or irritable mood with high energy, reduced need for sleep and impulsive, risky behavior. Hypomania is a milder, shorter version without marked impairment.

On the MCAT: A passage describes a patient's symptoms and timeline, and you classify the disorder. Bipolar I requires at least one manic episode. Bipolar II involves hypomanic and major depressive episodes. Depression with no history of mania is unipolar. Explanatory questions often use the monoamine hypothesis (low serotonin and norepinephrine activity), stress-related HPA axis activity, reduced hippocampal volume, learned helplessness, or negative thinking patterns.

Common confusion: Bipolar disorder is not rapid mood swings within hours, and it is not schizophrenia. It is defined by episodes of mania or hypomania, usually alternating with depression, that last days or longer. Mood disorders are defined by mood symptoms, not by psychosis, although severe episodes can include it.