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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2020). The mark or mark type is shown in brackets.

1. [8] Explanations of obsessive-compulsive disorder, including biomedical (genetic, biochemical and neurological); cognitive and behavioural; psychodynamic.
2. [8] Biomedical - Genetic - Genes such as PTPRD, SLITRK3 (both, and DRd4 (related to uptake of dopamine) have been found to have a possible role in OCD type symptoms;
3. [8] Biomedical - Biochemical - Oxytocin dysfunction – increase in worries and fear of certain situations/stimuli with the belief that survival could be threatened;
4. [8] Biomedical - Neurological – abnormalities of brain structure and function. Basal ganglia implicated in being related to obsessive-thinking. Also orbitofrontal cortex and anterior cingulate gyrus (used to check warning messages about threatening stimuli). Possibly basal ganglia no longer receiving these messages. Candidates may also refer to striatum, thalamus and the caudate nucleus. A malfunction in these areas may lead the OCD patient to continue to receive messages to do 'survival' type activities (such as hand-washing) even when this has already been done by the person.
5. [8] Cognitive and behavioural – (Cognitive) This explanation is linked to obsessive thinking. These thoughts lead to increased levels of stress and anxiety for the person. The reasoning behind the thoughts is faulty (e.g. the toilet is covered in harmful germs that could kill). Stressful situations can make these thoughts worse.
6. [8] Cognitive and behavioural – (Behavioural) This leads to compulsive behaviour which reduces the obsessive thoughts for a time and acts as the negative reinforcer of the behaviour (as something unpleasant is removed). Cognitive and behavioural can be described separately or together.
7. [8] Psychodynamic – Arise from the anal stage of psychosexual development. There may have been difficulties between the child and parent at this stage when the child defecated or urinated. Children may become either anally expulsive or anally retentive and the individual may become fixated at this stage. Compulsive cleaning or other rituals may help to soothe the early childhood trauma. Could also be the id and the superego in conflict with each other. The obsessive cleaning could act as an ego defence mechanism to deal with this conflict.
8. [10] Named issue – determinism – to an extent all explanations of OCD could be argued to be deterministic. With biomedical explanation we have no free will over our genetics. Similarly, we cannot exert free will within a psychodynamic explanation. Cognitive/behavioural could be seen as less deterministic as we can change our thinking to an extent. Different types of determinism – biological, environmental and psychic;
9. [10] Nature/nurture;
10. [10] Comparison of different explanations;
11. [10] Usefulness (effectiveness) of different explanations;
12. [10] Scientific nature of explanation (or not);
13. [10] Reductionist nature of the explanation;