OCD- biological explanation

Question 1

2 explanations for OCD

Answer 1

Genetic and neural

Question 2

Genetic explanation

Answer 2

Diathesis stress model- born with a vulnerability to OCD but something in environment trigger it
Lewis found- 37% had parents, 21% siblings with OCD

Candidate gene- SERT gene implicates OCD, serotonin not at normal levels- serotonin transporter

Polygenic OCD- COMT gene is enzyme that breaks down dopamine. OCD has high levels due to enzyme not breaking done dopamine properly

Aetologically heterogeneous- group of genes could cause

Question 3

Neural explanation

Answer 3

Genes associated with OCD affect neurotransmitter levels

Serotonin- regulates mood, some OCD can be explained by low S. low mood

Dopamine- excessive dopamine affects concentration

Decision making system- some cases (hoarding) associated with abnormal function of lateral and orbital prefrontal cortex- responsible for logical thinking

Caudate nucleus- area responsible for repressing worry signals,

Question 4

Strength Genetic explanation OCD (family)

Answer 4

Nestadt- found 68% of MZ twins had OCD opposed to 31% DZ twins.
Marini- someone with a family member with OCD is around 4x as likely to develop.

Question 5

Strength Genetic OCD (animals)

Answer 5

Ahmari- found genetic variations associated with repetitive behaviours and possible causes of OCD in other species (mice).

However
Although mice and humans
share most genes, the human mind and brain
are much more complex and it may not be
possible to generalise from animal repetitive
behaviour to human OCD.

Question 6

Limitation genetic OCD (environment)

Answer 6

Ignores environmental factors
Strong evidence for genetic predisposition but OCD not entirely genetic.
Cromer found half of OCD clients has trauma from past. More severe in those with one or more traumas

Question 7

Strength Neural OCD (evidence)

Answer 7

Antidepressants working solely on serotonin are effective in reducing OCD symptoms, supporting idea neurotransmitter is involved

Further evidence to show some neural systems like serotonin don’t work normally in those diagnosed with OCD

TREATMENT FALLACY

Question 8

Weakness Neural OCD (correlation)

Answer 8

Simply correlational evidence between neural abnormality and OCD

No cause and effect,
OCD could cause abnormalities or could be third factor

Question 9

Weakness Neural OCD (unique)

Answer 9

Not a unique neural system for OCD.
OCD not only disorder with serotonin issue.
Many with OCD also have depression involving disrupted serotonin
Creates chicken and egg issue.
Is serotonin disruption in OCD because they are depressed?