Genetic causes of OCD

Question 1

COMT gene

Answer 1

• Genes can be the main cause of OCD as OCD might be inherited whereby sufferers have a genetic vulnerability to get the illness.
• Psychologists use family or twin studies to investigate genetics.
• OCD is polygenic as
  one single gene is not responsible for the disorder. Instead, many genes might be responsible for causing OCD and these are known as candidate genes.
• COMT gene regulates production of neurotransmitter dopamine, where high levels of it is associated with OCD.
• COMT gene is more common in OCD patients.

Question 2

SERT gene

Answer 2

• Affects the transportation of serotonin which results in low levels of serotonin which leads to low mood and depressive symptoms.
• SERT gene is on chromosome 17 and a mutation of this gene can cause OCD.
• Research conducted by psychologists shows that 6/7 family members who has OCD has a mutation of SERT gene.

Question 3

Strength: Research support

Answer 3

• Nestadt (2000) found that people who had a first degree relative who already had OCD were five times more likely to get the illness.
• Billett (1998) found that from a meta-analysis of 14 twin studies that OCD is twice more likely to be concordant in identical monozygotic twins than dizygotic.

Question 4

Weakness: Concordance rate

Answer 4

• The concordance rate for OCD is not 100% so OCD cannot be caused entirely by genetic factors.
• Genetic explanation fails to take into account psychological and environmental factors.

Question 5

Weakness: Behavioural approach

Answer 5

• Behavioural approach contradicts the genetic explanation for OCD.
• The Two Process Model suggests that OCD can be learnt via classical conditioning and then maintained via operant.
• Behavioural approach has gained a lot of support in explaining the cause of OCD as behavioural therapies such as Exposure is used to treat OCD.

Question 6

Research by Beekman and Cath

Answer 6

• Meta analysis was conducted of twin studies into OCD that occurred over the last 70 years.
• MZ twins were compared against DZ twins.
• 10,034 twin pairs were studies overall.
• The results found that in children, OCD is inherited via genes and the genetic influence ranges from 45-65%.
• In adults, OCD is inherited via genes and the genetic influence ranges from 27-47%.
• Conclusion that OCD is transmitted genetically but it’s more apparent in children.

Question 7

Weakness Beekman and Cath: Controlled condition

Answer 7

• Research can be criticised as majority of twin studies were not performed in controlled conditions.
• The data is not very objective or scientific which may affect the validity and reliability of results.

Question 8

Weakness Beekman and Cath: Gene mapping

Answer 8

• Gene mapping was not taken into consideration.
• Gene mapping would look close at DNA of the twins that had OCD and compare this with twins that don’t.
• Comparisons need to be made for the results to be more valid.

Question 9

Strength Beekman and Cath: Long period

Answer 9

• Determines that a cause of OCD to be genetic in childhood and adulthood and the data was retrieved from a long period of time.