Biological Explanations For OCD (Psychopathology) Flashcards
(24 cards)
OCD is polygenic. What does this mean?
OCD is not caused by one gene, but caused by a combination of genetic variations that together significantly increase the vulnerabilities of developing OCD.
What is the COMT gene?
- Production of dopamine
- A variation leads to higher levels of dopamine –> more common in those with OCD
What is the SERT gene?
- Affects the transport of serotonin –> causes lower levels of serotonin associated with OCD
What is the Basal Ganglia?
- Connected to brain stem
- Responsible for coordination of movement
What is the Orbitofrontal Cortex?
- The frontal lobe
- Converts sensory information into thoughts and actions.
What are the emotional characteristics to OCD?
-
Anxiety/Distress: unpleasant and frightening.
-** Depression**: Accompanies OCD, reduces anxiety but they are only short term fixes. - Guilt/disgust: Can be about the self or external factors (e.g. dirt), guilt is irrational.
What are the behavioural characteristics to OCD?
- Compulsions –> Repetitive: habitual e.g. handwashing, counting, ordering.
- Compulsions –> Anxiety reduction: only 10% of OCD shows compulsions without obsessions.
- Avoidance: Sufferers may attempt to avoid anxiety by avoiding situations e.g. germ avoiders avoiding putting out the bins.
What are the cognitive characteristics to OCD?
- Obsessive thoughts: 90% of sufferers have reoccurring thoughts that are unpleasant.
- (Cognitive) coping strategies: Devise own way to cope with obsessive thoughts e.g. obsessive thoughts of family members dying can choose them to pray.
- Awareness of excessive anxiety: Aware of their thoughts/behaviours not being rational, hyper-vigilant and alert of potential hazards.
What is the diathesis stress model?
- Some people are more likely to develop a mental disorder.
- Some environments can trigger the condition.
What are candidate genes?
- Genes that are vulnerable to OCD.
- Some of these genes are involved in regulating the development of serotonin.
What does there being different types of OCD mean?
- A group of genes that cause a different type of OCD in one person, and a completely different type of OCD in another.
Research to support genetic explanations
+ Aubrey Lewis (1936) found after studying patients with OCD:
- 37% had parents with OCD
- 21% had siblings with OCD
+ Nedstadt:
–> Reviewed twin studies and found that 68% of MZ twins both had OCD in comparison to 31% of DZ twins
+ Family studies:
–> Someone with a family member who has been diagnosed with OCD is 4x more likely to also develop OCD themselves.
Weakness of genetic explanations
Methodological problems - research into families - they share genetic information and environmentOne weakness of genetic explanations for OCD is the methodological problems inherent in family studies. Aubrey Lewis (1936) found that 37% of OCD patients had parents with the disorder and 21% had siblings with OCD. Families share genetic information + environment. This makes it difficult to differentiate nature (genes) and nurture (environment) to the development of OCD. Therefore, while family studies might suggest a genetic link to OCD, they cannot definitively prove that the increased prevalence is solely due to shared genes, as shared environmental factors could also play a significant role
- Environmental risk factors:
–> Genetic variation can make a person more/less vulnerable
–> Evidence to suggest OCD isn’t entirely genetic
–> Environmental risk factors can increase/decrease the chances
E.g. Cromer et al found that over half of the clients suffering from OCD had experienced some kind of traumatic event in their past, and the OCD was more severe in those with one or more traumas.
(Neural explanations) - How is dopamine linked to OCD
Abnormally high dopamine levels link to OCD - Animal studies - found high doses of drugs that enhance dopamine levels induced movements resembling compulsive behaviour
How is serotonin linked to OCD
Low levels of serotonin link to OCD - antidepressant drugs which increase serotonin activity also reduces OCD symptoms (Pigott et al)
What do neurotransmitters do
Relay information from one neurone to another neurone
How do neurotransmitters and serotonin link to OCD
-OCD is triggered by communication problems between the brains deeper stricture and front part of the brain
-These parts of the brain use serotonin communicate
-This is why increasing serotonin help to alleviate OCD symptoms
What does the basal ganglia do -
(Neural explanations + brain structure)
coordinates movement and suppresses emotion
What does the frontal lobe (orbitofrontal cortex) do
Converts sensory information into thoughts and actions
How Is the frontal lobe and basal ganglia linked
The frontal lobe sends signals to the basal ganglia to worry about things.
The basal ganglia is supposed to suppress the worries
What would happen if the basal ganglia is damaged
-Patients would suffer OCD like symptoms as the basal ganglia cannot suppress the worry
-This would make the worry go back to the frontal lobe which leads to higher activity in the frontal lobe
What does this make the frontal lobe do
Frontal lobe will convert the worry into compulsions so the sufferer will repeat certain behaviours to reduce the worry (worry circuit)
Strength of neural explanations
+ Supporting evidence
–> Antidepressants that work soley on reducing serotonin are seen to reduce OCD symptoms, suggesting serotonin does play a part.
–> OCD symptoms can be seen in conditions known to be biological in origin, like Parkinson’s Disease which causes muscle tremors and paralysis, if a biological disorder can cause OCD symptoms, then the underlying cause for OCD must be biological.
COUNTERARGUMENT:
- However, the serotonin-OCD link may not be unique to OCD. Many people with OCD also suffer from clinical depression.
–> Comorbidity (having two disorders together)
- The depression is likely to involve disruption to the action of serotonin
–> Serotonin action may just be disrupted in people with OCD because they are depressed as well.
- May not be linked to OCD itself.
+ Practical application - drug therapies - SSRIs was created as a treatment for OCD as we know that low levels of serotonin causes OCD symptoms - therefore SSRIs increase serotonin levels - helped understand biochemistry to create treatments
Weakness of neural explanations
Correlation rather than cause + effect - Just because those with OCD show abnormalities in their neural systems does not mean that these abnormalities were the cause of the OCD. It could be the OCD that caused the abnormalities
