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9990 · 1.5.3

Treatment and management of obsessive-compulsive disorder — practice questions

Practice and worked examples for 9990 Treatment and management of obsessive-compulsive disorder. Short previews only — attempt the full question in MarkScheme against the official scheme.

Worked example 1

A patient with checking compulsions spends two hours daily verifying appliances are off. CBT alone has had limited success.

(a) Outline exposure and response prevention (ERP) for this patient. [4 marks] (b) Evaluate the use of SSRIs combined with CBT for OCD. Refer to treatment guidelines. [6 marks]

Show solution outline

(a) AO1 — ERP applied:

  • Exposure: Deliberate contact with trigger — leave house without checking oven/plugs (graded hierarchy from brief to extended absence).
  • Response prevention: Block checking ritual — resist urge to return and verify.
  • Mechanism: Anxiety rises then habituates without negative reinforcement — breaks operant maintenance cycle.
  • Therapist supports patient through distress; homework between sessions.

(b) AO3 — SSRI + CBT evaluation:

  • AO1: NICE/guidelines recommend CBT/ERP first-line; add SSRI (e.g. fluoxetine at higher dose) if moderate-severe or partial CBT response.
  • Strengths: RCTs show combination superior to SSRI alone for OCD — addresses both serotonin dysfunction and cognitive-behavioural maintenance.
  • Strengths: SSRIs may reduce anxiety enough for patient to engage with ERP — practical synergy.
  • Limitations: SSRIs have side effects (nausea, sexual dysfunction); 4–12 weeks to full effect; relapse if medication stopped without CBT skills.
  • Comparison: ERP alone effective for many — drugs add benefit when severity high (as in this case after limited CBT).

Judgement: For this patient, intensive ERP + SSRI is evidence-based escalation — combination addresses biological vulnerability and learned ritual maintenance.

Worked example 2

A patient's OCD symptoms are measured using the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) before and after a 12-week course of treatment with an SSRI. A score of 32-40 is 'extreme', 24-31 is 'severe', 16-23 is 'moderate', and 8-15 is 'mild'.

  • Baseline score (Week 0): 31
  • Post-treatment score (Week 12): 19

(a) Calculate the percentage improvement in the patient's Y-BOCS score. Show your working. [2 marks] (b) Using the data, explain why this treatment would be considered effective. [2 marks]

Show solution outline

(a) Calculation of percentage improvement:

  • Formula: ((Initial Score - Final Score) / Initial Score) * 100
  • Step 1: Find the absolute reduction. 31 (Initial) - 19 (Final) = 12 point reduction
  • Step 2: Calculate the percentage. (12 / 31) * 100 = 0.387 * 100
  • Answer: 38.7% improvement (rounded to one decimal place).

(b) Explanation of effectiveness:

  • AO2 Application: The treatment is effective because the patient's Y-BOCS score has moved from the 'severe' range (31) to the 'moderate' range (19). This represents a clinically significant reduction in symptoms.
  • AO2 Application: The 38.7% reduction in score provides objective, quantitative evidence of substantial improvement, demonstrating the efficacy of the SSRI treatment for this individual over the 12-week period.