Question 11: Explain [4 Marks] - Biological Explanations for OCD

Suggested Answer: There are two main biological explanations for obsessive-compulsive disorder (OCD): genetic and neural. Genetic explanations have focused on identifying specific candidate genes which are implicated in OCD.  It is believed that OCD is a polygenic condition, which means that several genes are involved. Two examples of genes that have been linked to OCD are the COMT gene and SERT. It might be that Bob has inherited one or both genes which is why the doctor is looking into Bob’s family history, as these might be the cause of his OCD.

Neural explanations focus on different brain structures.  The orbitofrontal cortex is a region which converts sensory information into thoughts and actions. PET scans have found higher activity in the orbitofrontal cortex in patients with OCD. Bob may be experiencing increased activity in the orbitofrontal cortex which is why the doctor has sent Bob for a brain scan as this could also be the cause of his OCD.

Please Note: These answers have been produced without the knowledge of the mark scheme and merely reflect my attempt at producing a model answer on the day of the exam. These answers are not endorsed or approved by AQA.