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Major depressive disorder
Major depression is diagnosed when at least 5 of 9 symptoms are present for at least two weeks, and these must include low mood or anhedonia (loss of pleasure); before starting an antidepressant always ask about past mania and assess suicide risk.
Why it matters in the exam
Depression questions first test the diagnosis: the number of symptoms, the two-week duration, impaired function, and exclusion of a physical cause or substance (hypothyroidism, steroids, alcohol). Next come the differences between depression and grief, adjustment disorder, dysthymia (at least two years) and depression within bipolar disorder. The most dangerous question is a patient with depression who receives an SSRI and becomes manic — the sign that past mania should have been asked about.
On the treatment side, know that response to an SSRI starts after 2–4 weeks and is complete after 6–8 weeks, that treatment continues 6–12 months after remission of a first episode, and that recurrent episodes need years of treatment. In depression with psychotic features an antidepressant is combined with an antipsychotic or ECT is given, and ECT is also the fastest treatment in high suicide risk, catatonia and refusal to eat. Important side effects: sexual dysfunction and hyponatraemia with SSRIs, QT prolongation with citalopram, weight gain and sedation with mirtazapine, and the contraindication of bupropion in seizures and eating disorders.
Key points
- 5 of 9 symptoms, two weeks, including sadness or loss of pleasure.
- Ask about mania and assess suicidality before treatment.
- SSRI and psychotherapy; full response after 6–8 weeks.
- After remission continue 6–12 months.
- Psychosis, catatonia or acute suicidality → ECT.
Summary table
| Condition | Definition | Treatment | Exam notes |
|---|---|---|---|
| Mild major depression | 5 of 9 symptoms, two weeks, mild impairment | Psychotherapy (CBT) or an SSRI | Watch suicide risk at every severity |
| Moderate to severe depression | Marked functional impairment | SSRI or SNRI together with psychotherapy | 6–8 weeks to judge full response |
| Depression with psychosis | Delusions of guilt, poverty or illness | Antidepressant plus antipsychotic, or ECT | ECT is very effective and fast |
| Treatment-resistant depression | No response to 2 drugs at adequate dose and duration | Switch, add lithium or aripiprazole, ECT, esketamine | Check adherence and the diagnosis |
| Persistent depressive disorder (dysthymia) | Low mood most days for at least two years | Psychotherapy and an SSRI | Double depression is possible |
| Postpartum depression | Onset within 4 weeks of delivery (DSM) | Psychotherapy, SSRI (sertraline suits breastfeeding) | Differs from the baby blues, which pass within two weeks |
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Sources
- DSM-5-TR, American Psychiatric Association, 2022 — Depressive Disorders
- NICE guideline NG222, 2022 — Depression in adults: treatment and management
- CANMAT Clinical Guidelines for the Management of Adults with Major Depressive Disorder, 2023 update — Pharmacological treatments; neurostimulation
- Kaplan and Sadock's Synopsis of Psychiatry, 12th edition (2021) — Mood Disorders
Sources are given for further reading; the text is written afresh and not copied from them.
Reviewed by the Examqo AI Professor · 2026-11-02. The text may contain errors; when in doubt, check the source.