Mood disorders
Also known as: affective disorders
Mood disorders are psychiatric conditions marked by persistent disturbances in emotional state, chiefly the depressive disorders (such as major depressive disorder) and the bipolar disorders, which add episodes of mania or hypomania.
Mood disorders — also called affective disorders — are conditions in which a disturbance of mood is the central feature, severe or persistent enough to impair daily functioning. The two major branches are the depressive disorders and the bipolar disorders. (The DSM-5 formally separates these into "depressive disorders" and "bipolar and related disorders," but "mood disorders" remains the common umbrella term.)
Major depressive disorder requires at least two weeks of depressed mood or loss of interest (anhedonia) plus symptoms such as changes in sleep, appetite, energy, concentration, feelings of worthlessness or guilt, psychomotor changes, and thoughts of death — commonly summarized by the SIG E CAPS mnemonic. Persistent depressive disorder (dysthymia) is a milder depression lasting at least two years.
Bipolar disorders are defined by mood elevation. A manic episode — at least a week of elevated or irritable mood with grandiosity, decreased need for sleep, pressured speech, racing thoughts, distractibility, and risky behavior — defines bipolar I; depression is common but not required for the diagnosis. Bipolar II pairs hypomania (a milder, shorter elevation without marked impairment) with at least one major depressive episode, and cyclothymia involves years of fluctuating subthreshold symptoms. Across all mood disorders, suicide risk assessment is a clinical priority.
Mood disorders are tested widely: the NCLEX emphasizes nursing care, safety, and suicide precautions for depression and bipolar disorder; USMLE Step 1 tests diagnostic criteria, neurotransmitter findings, and pharmacology; and AP Psychology covers depressive and bipolar disorders within its mental and physical health unit.
Key takeaways
- Mood disorders center on persistent emotional disturbance: the depressive disorders and the bipolar disorders.
- Major depression requires two or more weeks of depressed mood or anhedonia plus associated symptoms (SIG E CAPS).
- A single manic episode defines bipolar I; bipolar II requires hypomania plus major depression.
- Suicide risk assessment and safety planning are central to managing any mood disorder.
- The NCLEX, USMLE Step 1, and AP Psychology all test mood disorder criteria and care.