Neural explanations for OCD

Question 1

Describe Abnormal Serotonin Functioning

Answer 1

• OCD has been linked with a low level of the neurotransmitter serotonin in the brain.
• Serotonin is a neurotransmitter responsible for regulating mood.
• In OCD, some receptors are thought to block serotonin from entering the cell so that serotonin levels are low as well as having their level of activity reduced.
  -This leads to a deficiency in the neurotransmitter in key areas of the brain, particularly the PFC – which is an area of the brain linked to decision making.
  -Hence, people with OCD may have too little serotonin which may lead to the anxiety associated with OCD.

Question 2

Describe Abnormal Dopamine Functioning

Answer 2

• OCD is associated with abnormally high dopamine activity in the basal ganglia – which is in the motor cortex and linked to movement. - The basal ganglia is at the heart of the brain’s reward system – the
  satisfaction associated with performing a behaviour may lead to that behaviour being repeated in individuals with OCD.

Question 3

A03 - Pet Scans

Answer 3

• Support for decreased activity of serotonin and/or excessive dopamine in patients with OCD come from PET scans that have revealed a significant reduction of Serotonin receptor availability in parts of the PFC
  -and excessive dopamine in the basal ganglia in OCD patients
• Neuroimaging studies also suggest that the OFC may
  be a causal factor of OCD.
• PET scans have indicated that OCD sufferer’s exhibit increased glucose metabolism in the OFC-caudate nuclei loop, burning energy more rapidly in this network than do controls.
• This increased metabolism is also correlated with the severity of OCD.
  -These results point to the role of neural correlates in OCD, the scans simply reveal a correlation.
  -They do not establish cause and effect and therefore can’t be
  used conclusively to determine that neural correlates are the sole - factor in the role of OCD.

Question 4

A03 - Reductionist

Answer 4

• These biological explanations are highly reductionist as they reduce the complex behaviour of OCD down to a relatively simple level of explanation
  -Whilst this allows for concentrated investigation into localised areas of the brain and specific neurotransmitters, it is unlikely that brain structures and neurotransmitters work in isolation.
  -For instance, there is strong evidence to show that, when neurotransmitter activity levels are reduced, other
  neurotransmitters respond and compensate for each other.
  -This is also true of brain structure, where the opposing hemisphere’s structure, or other parts of the brain, step in to restore normal functioning.
  -Other research strongly suggests that non-neural factors are likely to contribute to OCD, such as learning and cognitive processes. Hence, biological explanations of OCD are not a comprehensive explanation for all individuals with OCD.

Question 5

A03 - Research Studies

Answer 5

-Zohar et al (1996) found that selective serotonin reuptake inhibitors (SSRIs) have been shown to reduce symptoms for up to 60% of OCD sufferers by increasing the amount of serotonin available for use in the synaptic cleft.
-Hence, serotonin seems to be linked to the cause of OCD symptoms.
-Likewise, Denys et al (2004) found that patients may benefit from the addition of antipsychotics, which reduce dopamine activity, to their ongoing SSRI treatment.
- However, not all patients respond to drug therapy, for instance, in the Zohar et al study 40% of OCD patients did not respond to SSRIs, suggesting that, in some individuals, low levels of serotonin and high levels of dopamine are not the key influential factor.

-Hence, there may be other causation factors such as the environment and learned behaviours, this
questions the neural explanation as a comprehensive one for all individuals.