AO1 - Biological Explanations of OCD

• Genetics:

  1. OCD is due to physical factors in the body - as it tends to run in families, it suggests a genetic predisposition to OCD is inherited
• Genetics:

  2. OCD is due to the inheritance of one or many maladaptive genes, e.g. SERT
• Genetics:

  3. OCD is polygenic, meaning it is caused by a combination of genes that increase vulnerability to OCD
• Genetics:

  4. Specific genes are called 'candidate genes' which make an individual vulnerable to developing OCD, these are called COMT and SERT
• Genetics:

  5. SERT gene is involved in the transportation of serotonin (responsible for regulating mood) - if SERT gene is mutated, reduces serotonin activity levels which are associated with increase in anxiety and OCD symptoms

  *3rd mark in 8m essay*
• Genetics:

  6. COMT is involved in the regulation of dopamine - one form is more common in people with OCD, causes an increase in dopamine activity, associated with compulsions in OCD
• Neurochemical:

  1. OCD is due to an imbalance in neurotransmitters, specifically low levels of serotonin activity
• Neurochemical:

  2. Mutation in the SERT gene causes serotonin to be recycled too quickly back into the pre-synaptic neuron, before it can activate the post-synaptic neuron
• Neurochemical:

  3. Low levels of serotonin can lead to anxiety, which can be linked to obsessions in OCD
• Neuroanatomy:

  1. OCD is associated with faulty decision making in the brain - neuroanatomy refers to the size, shape and function of certain areas of the brain and how they are linked to OCD
• Neuroanatomy:

  2. OCD is associated with abnormal functioning in the frontal lobe - responsible for logical thinking and decision making
• Neuroanatomy:

  3. There is evidence to suggest that the parahippocampal gyrus is associated with processing unpleasant emotions such as anxiety, which functions abnormally in people with OCD