9990 · 1.5.2
Explanations of obsessive-compulsive disorder flashcards
Revision flashcards for Cambridge 9990 Explanations of obsessive-compulsive disorder (syllabus 1.5.2). Flip, recall, then mark a real past-paper question.
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Genetic evidence in OCD?
MZ twin concordance higher than DZ; OCD runs in families — polygenic inheritance, no single gene identified.
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Serotonin explanation?
Low serotonin linked to OCD; SSRIs and clomipramine (tricyclic) reduce symptoms — supports neurotransmitter role.
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Brain circuits in OCD?
Overactivity in **orbitofrontal cortex** and **caudate nucleus** loop — hyperactive error-detection circuitry.
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Salkovskis — inflated responsibility?
Belief that one has power to prevent harm AND duty to do so — drives neutralising compulsions.
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Thought-action fusion?
Belief that having a thought is morally equivalent to acting on it, or makes the event more likely — maintains obsessions.
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Operant maintenance?
Compulsion temporarily reduces anxiety → **negative reinforcement** → ritual strengthened despite long-term worsening.
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What is the role of the COMT gene in OCD?
The COMT gene regulates the neurotransmitter dopamine. A specific variation of the COMT gene, which results in higher dopamine levels, has been found to be more common in individuals with OCD than in the general population.
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Explain the 'worry circuit' implicated in OCD.
A neural pathway involving the orbitofrontal cortex (OFC), caudate nucleus, and thalamus. The OFC sends signals about potential threats. The caudate nucleus normally suppresses minor worry signals. In OCD, this circuit may be overactive or dysregulated, possibly due to low serotonin, leading to persistent obsessions.
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What is 'thought-action fusion'?
A cognitive bias common in OCD where an individual believes that: 1) simply having an intrusive thought is morally equivalent to performing the action, or 2) thinking about an unwanted event makes it more likely to happen.
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How does negative reinforcement maintain compulsions in OCD?
The obsession causes anxiety (an unpleasant stimulus). Performing the compulsive behaviour reduces this anxiety. The removal of the unpleasant anxiety state is negative reinforcement, which strengthens and makes the compulsive behaviour more likely to be repeated in the future.
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What is the diathesis-stress model in the context of OCD?
An interactionist model suggesting that individuals may have a genetic predisposition or vulnerability (diathesis) for OCD. The disorder is then triggered and develops only when the individual experiences a significant environmental or psychological stressor.