bio app to expl ocd Flashcards
Two types of bio expl
Genetic explanations
Nerual explanations
Genetic explanations
The COMT gene
The SERT gene
Diathesis-stress
Genetic explanations suggest…
OCD is inherited and that individuals inherit specific genes which cause OCD
The COMT gene
The COMT gene is involved in the production of COMT which regulates dopamine
One variation of the COMT gene produces lower activity of the COMT gene which results in higher levels of dopamine and this variation is more common in patients with OCD, in comparison to people without OCD.
Variant of comt gene= higher dop levels
Higher dop levels are assoc OCD
The SERT gene
The SERT gene is linked to the neurotransmitter serotonin and affects the transport of the serotonin causing lower levels of serotonin which is also associated with OCD.
Diathesis-stress model
Genes such as the SERT gene are also implicated in a number of other disorders such as depression and post-traumatic stress disorder.
What this suggests is that each individual gene only creates a vulnerability (a diathesis) for OCD as well as other conditions, such as depression. Other factors (‘stressors’) affect what condition develops or indeed whether any mental illness develops.
Therefore some people could possess the COMT or SERT gene variations but suffer no ill effects.
Neural explanations for OCD
Abnormal levels of neurotransmitters
Abnormal brain circuits
Abnormal levels of neurotransmitters
The neurotransmitter dopamine has been implicated in OCD, with higher levels of dopamine being associated with some of the symptoms of OCD, in particular the compulsive behaviours.
The neurotransmitter serotonin has also been implicated in OCD, with lower levels of sertotonin being associated with OCD. This conclusion is based on the fact that antidepressant drugs that increase serotonin activity have been shown to reduce OCD symptoms
Abnormal brain circuits
Two brain regions have been implicated in OCD, including the caudate nucleus (in the basal ganglia) and orbitofrontal cortex.
The caudate nucleus normally suppresses signals from the orbitofrontal cortex.
In turn, the OFC sends signals to the thalamus about things that are worrying, such as a potential germ hazard.
When the caudate nucleus is damaged, it fails to suppress minor’ worry’ signals and the thalamus is alerted, which in turn sends signals back to the OFC, acting as a worry circuit.
This is supported by PET scans of patients with OCD, taken while their symptoms are active (e.g. when a person with a germ obsession holds a dirty cloth). Such scans show heightened activity in the OFC.
AO3:
str: family studies
str: twin studies
str/lim: antidepressants
lim: reductionist
str: family studies
Research from family studies.
Lewis: examined patients with OCD and found that 37% of the patients with OCD had parents with the disorder and 21% had siblings who suffered.
Research from family studies, like Lewis, provide support for a genetic explanation to OCD, although it does not rule out other (environmental) factors playing a role.
str: twin studies
Twin studies which have provided strong evidence for a genetic link.
Nestadt et al: conducted a review of previous twin studies examining OCD. They found that 68% of identical twins and 31% of non-identical twins experience OCD,
which suggests a very strong genetic component
However, no twin study has found a concordance rate of 100% in identical twins, which means that biological factors are not the only factor contributing to OCD and there must be environmental factors which also contribute to this disorder
str: antidepressants
Antidepressants such as SSRIs, which are used to regulate serotonin levels, have been effective in reducing OCD symptoms
This finding supports the idea that irregular levels of serotonin are linked to the development of OCD, which increases the validity of the theory
However Not all OCD sufferers respond positively to SSRIs which reduces the external validity of the theory
If SSRIs cannot treat all individuals with OCD, then the cause may not be solely neural
lim: reductionist
Ignores other factors and is reductionist.
eg the biological approach does not take into account cognitions and learning.
Some psychologists suggest that OCD may be learnt through classical conditioning and maintained through operant conditioning stimulus (for example, dirt) is associated with anxiety and this association is then maintained through operant conditioning, where a person avoids dirt and continually washes their hands. This hand washing reduces their anxiety and negatively reinforces their compulsions.
suggets there may be psychological causes as well as biological
