Worked example 1
A patient spends three hours daily checking that the oven is off, driven by intrusive thoughts that the house will burn down. They know the fear is excessive but cannot stop.
(a) Identify one obsession and one compulsion in this case. Outline DSM-5 criteria for OCD. [4 marks] (b) Distinguish OCD from an impulse control disorder. Evaluate the validity of the obsession–compulsion distinction. [6 marks]
Show solution outline
(a) AO1 — Obsession: Intrusive thought that house will burn down — recurrent, unwanted, anxiety-provoking.
AO1 — Compulsion: Repeated checking of oven — performed to reduce obsession-related distress.
AO1 — DSM-5 criteria met:
- Obsessions and compulsions present.
- Time-consuming (>1 hour/day — three hours checking).
- Causes distress and impairment.
- Patient has insight — knows fear is excessive.
(b) AO1 — OCD vs ICD:
- OCD: act is anxiety-reducing ritual linked to obsession — ego-dystonic, no pleasure in compulsion.
- ICD: impulse acted on for gratification/relief of tension — pleasurable component, not neutralising specific obsession.
AO3 — Validity of distinction:
- Strengths: Clear clinical utility — guides ERP targeting rituals; different from kleptomania/pyromania profile.
- Limitations: Pure obsessional OCD (mental rituals only) blurs line; hoarding moved to separate category — suggests dimensional overlap.
- Comorbidity: OCD frequently co-occurs with depression and anxiety — shared neurobiology (serotonin) challenges pure categorical validity.
Judgement: Obsession–compulsion framework is clinically valid for this case but DSM-5 revisions show category is evolving.