Biological Approach to Explaining OCD Flashcards
Describe OCD
- An anxiety disorder. Sufferers experiences obsessions (persistent and inappropriate thoughts that aren’t based in reality) which they deal with through ritual behaviour, compulsions (uncontrollable urges to repetitively carry out behaviour to reduce anxiety)
- Very time consuming and they realise compulsions are short term fix
Outline the genetic explanation for OCD
Argues it is inherited through genetic transmission from one biological parent to child. Possible genes linked with OCD are the SERT and COMT gene. Research often examines concordance rates from family studies
Describe how the SERT gene is linked to OCD
- Affects the transport of serotonin, creating lower levels of the neurotransmitter, these lower levels are implicated in OCD
- Ozaki et al (2003) found a mutation of the SERT gene in two unrelated families where 6 of the 7 family members had OCD
Describe how the COMT gene is linked to OCD
- Regulates the production of dopamine that has been implicated in OCD.
- Genes come in different forms and one form of the COMT gene has been found to be more common in OCD patient than those without the disorder. Tukel et al (2013) found this variation produces lower activity of the COMT gene and higher levels of dopamine
Describe the diathesis-stress model
- The idea that a simple link between one gene and a complex disorder like OCD is unlikely. Genes like the SERT gene are implicated in a number of other disorders like depression and PTSD
- This suggests each gene only creates a vulnerability (a diathesis) for OCD as well as other conditions, like depression. Other factors (stressors) affect what condition develops or whether any mental illness develops. Therefore some may have the COMT or SERT gene variations but suffer no ill effects
Give evaluation for the genetic explanation (specific genes)
Research evidence examining specific genes linked with OCD. Ozaki examined the genetics of 2 families where 6/7 family members had OCD. They found a mutation in the SERT gene in these members. Suggests a genetic influence on OCD as supported by family studies.
Give evaluation for the genetic explanation (environment)
One weakness is OCD isn’t only caused by genetics. Cromer found over half the OCD patients studied had a traumatic event in their past. Therefore it’s likely OCD is explained more by a diathesis stress (environmental risk factors that increase the risk of developing OCD). Furthermore, children often show dissimilar OCD symptoms to their parents. This is an issue for genetic theories as we would expect the same behaviors if OCD was inherited
Give evaluation for the genetic explanation (concordance rates)
- Research evidence from concordance rates to support OCD being caused by genes. Nestadt (2000) found concordance rates of monozygotic (MZ) twins was 68% and of dizygotic twins (DZ) was 31%. Shows there’s a genetic influence on OCD. However, concordance rates aren’t 100%. Furthermore, a higher concordance rate in MZ might be due them sharing a more similar environment than DZ twins, rather that the fact the share more genes. This complicates the conclusions on whether it’s genes or environment which causes OCD
Outline the neural explanation for OCD
Argues OCD is caused by abnormalities in the brain. These include abnormal levels of neurotransmitters or abnormal brain circuits
Describe how abnormal levels of neurotransmitters is linked to OCD
- High levels of dopamine in the frontal lobes are linked to overactivity in these brain regions. Szechtman et al found evidence in this area based on animal studies, high doses of drugs that increase dopamine levels lead to stereotyped movements similar to compulsive behaviors in OCD individuals
- Low levels of serotonin is linked to OCD. Serotonin is an inhibitory neurotransmitter. This means if there are lower levels then less is able to prevent the post synaptic neuron from firing. Therefore there’s greater activity in the brain as the excitatory neurotransmitters have a greater effect on the post synaptic neuron
Describe how abnormal brain circuits is linked to OCD
- Those with OCD have a high level of activity in the orbitofrontal cortex (OFC), which is part of the brain responsible for logical thinking and decision making.
- Worry circuit: OFC sends signals to the thalamus about worrying things. The caudate nucleus usually suppresses worry signals sent to the OFC. If the caudate nucleus is damaged it doesn’t supress minor worries , the thalamus is alerted and confirms we worry then signals back to the OFC.
- Serotonin and dopamine are linked with these regions of the frontal lobes. Comer (1998) reports serotonin plays a key role in the operation of the OFC and the caudate nuclei and abnormal levels of serotonin may cause a malfunction. Suket (2007) reports high levels of dopamine might lead to overactivity of the basal ganglia.
Give evaluation for the neural explanation (link between serotonin and OCD)
Evidence to support the link between serotonin and OCD. Hu (2006) found lower serotonin activity in OCD patients than controls. Supports that the cause of OCD may be due to low levels of serotonin because those with OCD had lower activity of serotonin. However, it’s impossible to conclude that low serotonin is the cause of OCD as the research is only a correlation. It could be possible having OCD causes lower serotonin.
Give evaluation for the neural explanation (increase in serotonin)
Research has shown increasing levels of serotonin do seem to reduce symptoms of OCD. For example, SSRI’s (selective serotonin reuptake inhibitors) increase serotonin and do seem to be effective treatment for OCD. This supports that the cause of the disorder may be low levels of serotonin as increasing it reduces symptoms. However, a drug can work without targeting the cause of a disorder. We can’t assume just because a drug works that it’s targeting the cause, known as the treatment-aetiology fallacy
Give evaluation for the neural explanation (combined with other disorders)
One issue is OCD is often combined with other disorders. For example, depression is often experienced by people with OCD. This is an issue because it’s possible that the low serotonin levels are actually the cause of depression and not OCD. Therefore, OCD would have to have another cause. It can be difficult to separate the causes of each disorder
