Outline + evaluate the biological approach to explaining OCD

Question 1

OCD characteristic

Answer 1

• obssessions + complusions accompanied w/ anxiety extreme distress and depression
• has a strong biological component

Question 2

Genetic explanation

Answer 2

Genes are involved in individual vunerability to OCD

• Lewis observed his patients: 37% had parents w/ OCD and 21% had siblings => SUGGEST must run in the family
• Diathesis-stress model: genetic propensity for OCD is passed and environmental stressor triggers it

Question 3

Researchers identified genes for OCD

Answer 3

• Candidate genes create vulnerability for OCD

=> The COMT gene regulates the production of dopamine
=> The SERT gene or 5H-TT affects transport of serotonin creating lower levels

study of 2 unrelated families where 6-7 members had OCD found a mutation of this gene

Question 4

OCD may be polygenic

Answer 4

Supported by Taylor - found evidence up to 230 genes in OCD

Question 5

Aetiologically Heterogenous

Answer 5

One group of genes may cause OCD in one person while diff group may cause it in another

• Thus has many causes and different combinations of genes may cause it in diff people

Question 6

Supporting evidence for genetic vulnerabliity - Twin studies

Answer 6

Nestadt et al - found concordance of 68% in MZ twins vs compared 31% in DZ twins

Question 7

AO3 of evidence for genetic vulnerability (S)

Answer 7

Comparing MZ and DZ twins as genetic evidence may overlook that MZ may have more similar environments than DZ
=> may contribute to the illness

Concordance in MZ twins - clones - is far from 100% suggesting other environmental factors that contribute to OCD

Question 8

Environmental risk factors increasing risk of OCD

Answer 8

Cromer et al - found over 1/2 of OCD patients in sample had a traumatic event and was more severe in those w/ trauma

=> suggests a diathesis-stress model is more appropriate for OCD + better to focus on environmental causes as we can prevent

Question 9

OCD’s effect on neurotransmitters

Answer 9

• Is thought if a person has low levels of serotonin then normal transmission of mood relevant info doesnt take place

=> affects mood => thus some cases of OCD may be explained by reduced function of serotonin system in brain

Question 10

Supporting evidence for effect of neurotransmitters (S)

Answer 10

Antidepressants that work soley on serotonin system effectively treat OCD

Question 11

AO3 of evidence - treatment aetiology fallacy (L)

Answer 11

Just because SSRIs - make serotonin available - cure OCD in some cases doesnt mean the serotonin dysfunction caused it

Question 12

AO3 Neural abnormalities could be a symptom (L)

Answer 12

Many who suffer OCD are also depressed => may be involved in distruption of serotonin system

Depression is link not OCD

Question 13

AO3 - biological explanation is reductionist (L)

Answer 13

reduces complex illness to a matter of genes + neurotransmitters and ignores other causes like environmental

Question 14

AO3 - 2 process model can be applied

Answer 14

• Initial learning when neutral stimulus like dirt is associated w/ anxiety
• association is maintained as stimulus is avoided and O + C behaviors result

Question 15

Support of 2 process model causing OCD

Answer 15

Success of a treatment for OCD called exposure and response prevention (ERP) - similar to SD/flooding +

=> patients experience feared stimulus + prevented from performing C behavior
=> 60-90% of adults improved w/ ERP