OCD Flashcards
What type of disorder is OCD?
Anxiety disorder
What are the cognitive characteristics of OCD?
- Obsessive thoughts
- Strategies to deal with obsessions
- Hypervigilance
- Cognitive insight into irrational behaviours
- Ruminations/doubts
- Perfectionism
What are the behavioural characteristics of OCD?
- Compulsions are repetitive
- Compulsions reduce anxiety
- Rituals
What are the emotional characteristics of OCD?
- Anxiety/distress
- Depression
- Guilt and/or disgust
What are the genetic explanations for OCD?
- OCD is inherited (MZ 70-80% concordance and DZ 22-47% concordance)
- OCD is polygenic (up to 230 genes may be involved)
- One group of genes mat cause OCD in one person, but another group may cause it in someone else (aetiologically heterogeneous)
What genes are known to be involved in causing OCD?
- COMT gene (regulates dopamine production) produces lower COMT and higher dopamine when mutated: dopamine levels are abnormally high in OCD patients
- SERT gene (affects transport of serotonin) leads to lower levels of serotonin when mutated, which is typical of those with OCD
What is an evaluation for the strength of OCD genetic explanations?
Support from family and twin studies
* There is strong evidence for the genetic basis of OCD
* Nestadt et all identified 80 patients with OCD and 343 of their first degree relatives. They compared them with 73 control patients without mental illness and 300 of their relatives. They found that people with a first degree relative with OCD had a 5x greater risk of developing the disorder compared to those without.
* Furthermore, a meta analysis of 14 twin studies found that MZ twins were >2x as likely to develop OCD if their co-twin had it compared to DZ twins (68% vs 31%)
* This shows that there is a clear genetic basis for OCD, but shows environmental facots must play a role as concordance rates are never 100%
What is the evaluation for the weakness of the OCD genetic explanation?
Environment plays a role
* These cannot be the sole cause of the disorder
* Genes may icnrease the risk of developing it, but environmental facots can also trigger/increase risk of developing OCD
* Cromer et al found that over half the OCD patients in their sample had experienced a traumatic event in their past, and OCD was more severe in those with multiple traumas.
* This demonstrates that OCD cannot all be entirely genetic in origin, and also suggests that it may be more productive to focus on the environmental causes that we can do more about
What is the diathesis-stress hypothesis? What are the ‘diathesis’ and the ‘stressor’ attributes?
The theory that mental and physical disorders develop from a genetic/biological predispostition for that illness, combined with stressful conditions that play a facilitating role
Diathesis
* Genes
* Abnormalities in brain function
* Neurotransmitters
Stressors
* Bad physical stressors
* Trauma, abuse, neglect
* Relationships (loss, turbulence)
* Culture-related stressors
What is an evaluation for the strength of the diathesis-stress model?
Simple link is unlikely
* The idea of a simple link between one gene and a complex dirsorder like OCD is unlikely
* SERT genes are also implicated in other disorders such as depression and PTSD. This suggests the gene creates a vulnerability but does not guarantee this person will get that specific illness
* Other stressors affect what condition develops, therefore some people with the gene mutations could never get ill
* According to the model, mental illness develops through an interaction of biological vulnerability and environmental stressors (a combination of nature and nurture)
What are the neural explanations for OCD?
Abnormal levels of neurotransmitters
* Dopamine levels are abnormally high, found from evidence in animal studies
* Szechtman (1998) found that high doses of drugs that increased dopamine levels created movements in animals similar to those in human OCD patients
* It has been found that serotonin levels are low in those with OCD. Antidepressants that increase serotonin levels also reduce OCD symptoms, and those that have less effect on serotonin do not reduce OCD symptoms
Abnormal brain circuits
* Some areas in frontal lobes are thought to be abnormal
* The caudate nucleus in the basal ganglia supresses signals from the orbitofrontal cortex (OFC)
* The OFC sends signals to the thalamus about things worrying the person
* If the caudate nucleus is damaged it cannot suppress the OFC, so even minor signals are still sent to thalamus and then back to the OFC, creating a worry circuit
* This is supported by PET scans of patients with OCD which highlight heightened activity in the OFC when a person’s symptoms are active
- Serotonin also plays a key role in OFC operation and caudate nucleus, which show that varying levels of serotonin cause abnormal function
- Dopamine is linked to the basal ganglia as it is the main neurotransmitter in the brain region. High levels of dopamine may lead to overactivity.
What is the evaluation for the strength of OCD neural explanations?
Research support for OFC
* Many studies demonstrate the genetic link to abnormal brain regions
* MRI technology was used to produce images of brain activity in OCD patients and their immediate family members without OCD
* It was found that OCD patients and their close relatives had reduced grey matter in key regions of the brain, including OFC
* This supports the view that anatomical differences are inherited and may lead to OCD in certain individuals and also shows that brain scans may be used to detect OCD risk as a real life application of biological explanations.
What is the evaluation for the weakness of OCD neural explanations?
Only a correlation
* A major problem with neural mechanisms of OCD is that research is only correlational
* Even though there is evidence to suggest that various neurotransmitters and structures of the brain do not function normally in patients with OCD, it must not be assumed that they CAUSE OCD
* It can only be said that there is a link between neural mechanisms and OCD symptoms (correlation does not equal causation)
* This matters as the biological abnormalities seen in patients with OCD could well be a consequence of having the disorder, rather than a cause of the disorder and therefore would not be a valid explanation
What is an evaluation for an alternate explanation of OCD biological explanantions?
OCD is learnt
* One weakness of the biological approach for OCD is that it faces strong competition from psychological explanations
* The two process model can also effectively explain how OCD develops trhough learning. Initial leanring occurs through classical conditioning, associating a neutral stimulus with anxiety
* The association is then maintained through operant conditioning, where compulsions are performed that relieve anxiety and negative reinforcement occurs
* THis therefore suggests that OCD may have psychological causes aswell as, or instead of, biological causes
