A01

• What has research suggested

  • Research has suggested that genes are involved in individual vulnerability to OCD
• OCD is a what condition?

  • OCD is a polygenic condition, meaning there are many candidate genes involved in causing a vulnerability for OCD.
• Taylor (2013)

  • Taylor (2013) found there are as many as 230 different genes involved in OCD.​

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  Two of these candidate genes are the COMT gene and the SERT gene.
• Outline the COMT gene

  • Usually, the COMT gene released COMT, an enzyme which breaks down dopamine.​
  • But OCD has been related with a mutation in this gene, which causes higher levels of dopamine.
• Outline the SERT gene

  • This gene is responsible for the transportation of serotonin from the synapse back to the presynaptic cell. ​
  • A mutation in this gene increases the rate of reuptake which reduces the levels of serotonin in the post synaptic cell, which is related with OCD.
• Outline some neural explanations for OCD

  • Neural explanations for OCD focus on neurotransmitters and brain structures. ​​
  • They suggest that there are abnormal levels of certain neurotransmitters (in particular serotonin and dopamine) that are associated with OCD. ​​
  • These explanations also suggest that particular brain areas (basal ganglia and orbitofrontal cortex) are associated with OCD.
• What is serotonin involved in

  • involved with stabilising mood.
  • Lower levels of serotonin is associated with OCD.
• What is dopamine involved in

  • influences moods and feelings of reward and motivation.
  • Higher levels of dopamine is associated with OCD.
• Several areas in the

  • frontal lobe are thought to be abnormal in people with OCD
• What is the "worry loop" in the brain

  • The OFC sends signals about things that are worrying (e.g., germs) to the thalamus. The thalamus receives the signal and directs it to the OFC to be interpreted. Thus it is a loop.
• In people with OCD

  • the caudate nucleus is under functioning and thus fails to suppress minor ‘worry signals’. The thalamus is alerted, which in turn sends signals back to OFC, acting as a worry circuit.
• Which part of the brain is the caudate nucleus found in

  • Basal ganglia
• The frontal lobe is responsible for logical thinking and decision making. In OCD..

  • Impaired, causes impaired decision making (e.g., hoarding disorder).
• When functioning normally the Parahippocampal gyrus is responsible for...

  • associated with processing unpleasant emotions.
• In OCD

  • Impaired, leads to OCD.