Discuss neural explanations of obsessive-compulsive disorder (OCD)
Updated: 7 days ago
Discuss neural explanations of obsessive-compulsive disorder (OCD). Refer to neurochemical and brain-structure explanations in your answer.
[16 marks]
What is expected in the answer?
The command word “discuss” requires students to explain neural explanations of OCD and then evaluate how successfully abnormal neurochemistry and brain functioning account for the disorder. Because the question specifically names neurochemical and brain-structure explanations, both need to be covered clearly.
For 16 marks, stronger answers should explain the roles of neurotransmitters such as serotonin and dopamine, alongside abnormalities in structures or circuits including the orbitofrontal cortex, caudate nucleus, thalamus, basal ganglia and parahippocampal gyrus. Evaluation can consider supporting and contradictory biological evidence, the success and limitations of drug treatment, cause and effect, individual differences and links with genetic explanations.
Neural explanations form part of the biological approach to explaining OCD in the current specification.
Marks for this question: AO1 = 6, AO3 = 10
The June 2025 examination included a 16-mark question covering the neural explanation of OCD and drug therapy, using AO1 = 6 and AO3 = 10. The same allocation is therefore appropriate for this neural-focused extended question.
Level | Marks | Description |
4 | 13–16 | Knowledge of neural explanations of OCD is accurate and generally well detailed. Neurochemical and brain-structure explanations are clearly explained. Discussion is thorough and effective, using relevant evidence, limitations, cause-and-effect issues and/or comparisons with alternative explanations. The answer is clear, coherent and focused, with effective use of specialist terminology. |
3 | 9–12 | Knowledge of neural explanations is evident but there may be occasional inaccuracies or omissions. Both neurochemical and brain-structure explanations are addressed. Discussion is mostly effective and relevant evidence is used appropriately, although some points may lack development. |
2 | 5–8 | Limited knowledge of neural explanations is present. Neurochemical and/or brain-structure explanations may be insufficiently developed. The response is mainly descriptive and discussion is only partly effective. |
1 | 1–4 | Knowledge is very limited or muddled. There may be confusion between neural and genetic explanations. Discussion is limited, poorly focused or absent. Specialist terminology is absent or used inaccurately. |
0 | 0 | No relevant content. |
Indicative content
AO1: Neural explanations
Neural explanations propose that OCD is associated with abnormalities in the functioning of the brain and nervous system.
Two main areas can be considered:
abnormalities in neurochemistry
abnormalities in brain structures and neural circuits.
The June 2025 mark scheme identifies serotonin and dopamine imbalances alongside abnormalities involving the parahippocampal gyrus, basal ganglia and the orbitofrontal-caudate-thalamic circuit.
Neurochemical explanations
Serotonin
Credit relevant knowledge such as:
Serotonin is a neurotransmitter involved in communication between neurons.
Abnormal serotonin functioning has been associated with OCD.
Low or disrupted serotonin activity may result in abnormal transmission of information involved in:
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