Major Depressive Disorder

A patient tells you they've lost interest in everything for the past three weeks — is that grief, adjustment, or a disorder requiring treatment? The timeline and symptom count decide.

Major depressive disorder (MDD) requires at least five of nine DSM-5 symptoms present nearly every day for a minimum of two weeks, with at least one being depressed mood or anhedonia (loss of interest/pleasure). The mnemonic SIG-E-CAPS captures the remaining symptoms: Sleep changes (insomnia or hypersomnia), Interest loss, Guilt/worthlessness, Energy loss, Concentration difficulty, Appetite/weight changes, Psychomotor agitation or retardation, and Suicidal ideation. Nursing assessment focuses on observable changes: flat affect, psychomotor retardation (slow speech, delayed responses, decreased movement), poor hygiene and grooming, social withdrawal, and tearfulness. Screen using validated tools like the PHQ-9, where a score of 10 or above suggests moderate depression requiring intervention. Vegetative symptoms — sleep, appetite, energy, psychomotor changes — are the most objectively assessable by nurses and often the earliest indicators that treatment is or isn't working. A patient who reports improved mood but still can't sleep or eat hasn't fully responded.

Key Distinctions

Don't confuse MDD with bipolar depression — asking about any history of manic episodes is critical before antidepressant initiation, as antidepressants can trigger mania. Don't mistake psychomotor retardation for medication sedation in a newly admitted patient. Students confuse normal grief (symptoms wax and wane, self-identity preserved) with MDD (persistent, pervasive worthlessness, functional impairment lasting beyond two weeks).

Clinical Pearl

SIG-E-CAPS: think of the doctor writing a prescription for energy capsules — Sleep, Interest, Guilt, Energy, Concentration, Appetite, Psychomotor changes, Suicidal ideation. Five of nine, two weeks minimum.