Depression and bipolar disorder together account for the largest proportion of general adult psychiatry questions in Paper B. The two conditions are often examined together because the differential diagnosis between unipolar depression and bipolar depression is a recurring question pattern. This guide covers the classification, NICE-recommended management, key trial evidence, and the specific question formats used in the examination.
Depressive Disorders: ICD-11 Classification
ICD-11 divides depressive disorders into single episode depressive disorder and recurrent depressive disorder. Both are further classified by severity: mild, moderate, and severe with or without psychotic symptoms. The key distinction from ICD-10 is that the symptom list is simplified and the duration requirement remains at least 2 weeks.
Core symptoms (at least 2 required): Depressed mood, loss of interest or pleasure (anhedonia), reduced energy or fatigue.
Additional symptoms: Reduced concentration and attention, reduced self-esteem and self-confidence, ideas of guilt and unworthiness, bleak and pessimistic views of the future, ideas or acts of self-harm or suicide, disturbed sleep (any pattern), diminished appetite or overeating. Mild = 2 core + 2-3 additional. Moderate = 2 core + 4-5 additional with functional impairment. Severe = all 3 core + 5+ additional, marked functional impairment, with or without psychotic symptoms.
Exam pattern: Questions often give a vignette with specific symptom count and ask for the severity grade. The key is matching the number of symptoms to the severity category, not just clinical intuition.
NICE Depression Treatment Algorithm
NICE uses the stepped care model for depression (CG90, updated 2022). The examination tests your knowledge of which intervention at which severity level.
Step 1 (All severities): Assessment, psychoeducation, sleep hygiene, active monitoring. No active intervention required for subthreshold or mild symptoms that are not persisting.
Step 2 (Persistent subthreshold or mild depression): Low-intensity psychosocial interventions (guided self-help based on CBT principles, computerised CBT, structured group physical activity) OR medication if preferred. For mild depression, NICE recommends low-intensity CBT before medication. This is a frequently tested point: the exam expects you to offer low-intensity intervention first for mild depression, not an antidepressant.
Step 3 (Moderate to severe depression): High-intensity psychological intervention (CBT or IPT) combined with an antidepressant (SSRI first-line). The combination of medication and psychological therapy is superior to either alone for moderate-severe depression.
Step 4 (Treatment-resistant, life-threatening): Multi-disciplinary review, augmentation strategies, ECT if rapid response needed. ECT is indicated for severe depression with psychotic features or catatonia, or where a rapid response is required (high suicide risk, food/fluid refusal).
Antidepressant Selection
First-line: An SSRI (sertraline is NICE first-choice due to favourable side-effect profile and safety in overdose). Fluoxetine has the longest half-life (4-6 days) and lowest discontinuation syndrome risk. Citalopram has the most drug interaction data but QTc prolongation at high doses restricts it.
Switching strategies: If no response after 3-4 weeks at therapeutic dose, optimise dose first. If no response after 6-8 weeks, switch to a different SSRI or an alternative class (SNRI, mirtazapine). There is no evidence from STAR*D that any switch strategy is superior. Evidence-based augmentation options: lithium augmentation (best evidence), aripiprazole augmentation (licensed in the USA for TRD), quetiapine augmentation, or combining mirtazapine with an SSRI/SNRI.
STAR*D Trial Data (Essential for the Exam)
The Sequenced Treatment Alternatives to Relieve Depression (STAR*D) trial is the most commonly referenced antidepressant trial in Paper B. Key findings you must know:
- Level 1 (citalopram): 36.8% remission (QIDS-SR16 less than or equal to 5)
- Cumulative remission after 4 steps: approximately 67%
- No significant difference between switching to another antidepressant and augmenting at any level
- No significant difference between switching within-class (another SSRI) and across-class (SNRI, bupropion)
- When patients who could not tolerate or did not respond to citalopram were switched to sertraline, bupropion, or venlafaxine, remission rates were similar (~17-21%)
Bipolar Disorder: ICD-11 Classification
Bipolar type I: At least one manic episode (most patients also have depressive episodes). Mania requires elevated mood OR irritability, plus increased activity or energy, lasting at least 1 week (or any duration if hospitalisation required). Additional symptoms: grandiosity, decreased need for sleep, pressured speech, flight of ideas, distractibility, increased goal-directed activity, excessive involvement in risky activities.
Bipolar type II: At least one hypomanic episode and one depressive episode. Hypomania lasts at least 4 days, does NOT cause marked functional impairment, does NOT require hospitalisation, and has NO psychotic features. The distinction from mania is the functional impact threshold, not just the symptom count.
Cyclothymic disorder: Chronic fluctuating mood disturbance with numerous hypomanic and depressive periods that do not meet full criteria for either, present for at least 2 years.
Exam pattern: A vignette describing elevated mood with increased energy and reduced sleep for 5 days with some functional impairment but no psychosis or hospitalisation. Answer: hypomania (not mania, not anxiety).
Bipolar Management: NICE Algorithm
Acute mania: First-line: haloperidol, olanzapine, quetiapine, or risperidone. If inadequate response after 2 weeks, switch to an alternative first-line or add lithium. If still no response, add valproate (but not in women of childbearing potential). Avoid antidepressants in acute mania.
Bipolar depression: First-line: quetiapine (the only drug licensed for bipolar depression in the UK) or olanzapine plus fluoxetine (Symbyax in the USA). Fluoxetine alone is NOT recommended as the switch to mania risk is significant. Lithium and lamotrigine have evidence for bipolar depression prevention but are not first-line for acute treatment.
First trimester bipolar: A recall question: a woman in first trimester with mixed affective state. Olanzapine or quetiapine are safer than valproate or lithium. Valproate is absolutely contraindicated in pregnancy. Lithium carries Ebstein’s anomaly risk in first trimester (but this is lower risk than valproate teratogenicity).
Maintenance: First-line: lithium (most evidence for preventing both manic and depressive relapse). Alternative: valproate (but not in women of childbearing potential), olanzapine, quetiapine. The BALANCE trial (2010) showed that lithium plus valproate was more effective than valproate alone, and lithium alone was comparable to combination therapy. This is an exam-favourite finding.
High-Yield Recall Patterns for Mood Disorders
- Olanzapine discontinued, relapses with depression: Do NOT restart olanzapine. Start lamotrigine (if mood stabiliser needed) or quetiapine (option depending on answer set). Fluoxetine alone is rarely correct in bipolar depression.
- Mixed affective state + first trimester: Olanzapine or quetiapine. Valproate contraindicated.
- Valproate + abdominal pain + vomiting + elevated amylase: Pancreatitis. Stop valproate.
- Lithium + thirst + polyuria + fine tremor: Lithium-induced nephrogenic diabetes insipidus.
- Lamotrigine + target lesions + blistering: Stevens-Johnson syndrome. Stop lamotrigine.
- STAR*D meaning: No single strategy (switch vs augment) is superior. ~67% cumulative remission by step 4.
PsychStar’s Paper B question bank covers depression and bipolar disorder with questions aligned to NICE guidelines and trial evidence. Start with 5 free questions at psychstar.io/try.