Biological Approach - OCD

What are biological explanations to explaining OCD?
many physical illnesses have genetic cause, same may be true for a mental illness like OCD
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What are the 2 biological explanations?
Family Studies and Candidate Genes
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What are Family Studies?
can identify whether OCD tends to run in families, showing inheritable disorder.
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What did Nestadt find?
first degree relatives of individual OCD had 11.7% probability of suffering compared to 2.7% in control group. This is a 5x increase in incidence of OCD in close relatives (due to shared genes). If genetic, one twin suffers, other twin expected to
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What did Miguel find?
studied identical twins and found concordance rate of 54-87%
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advantages of family studies
fact that close relatives of person with OCD are more likely to have it themselves suggest genes are involved. Concordance rates in Miguel are high suggesting genetic component very strong
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disadvantage of previous advantage
if OCD solely caused by genes, the concordance rate for identical twins would be 100%
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disadvantage of family studies
can't rule out an environmental explanation of OCD running in families, could be observation and reinforcement. e.g. child observes parent washing and encourages child to do so
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What are candidate genes?
specific genes that influence vulnerability to OCD. Thought to do this by influencing neural activity and brain strucutre
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What genes influence OCD?
COMT Gene & SERT & 5HTI - D beta
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What is the COMT Gene?
regulates activity of neurotransmitter dopamine. one variation results in higher levels of dopamine, which is more common in people with OCD
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What is the SERT and 5HTI - D beta Gene?
influence region of seretonin and are implicated in the development of OCD
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Advantage of candidate genes as explanation of OCD?
TAYLOR - found as many as 230 genes that may be involved in causing OCD, supporting idea OCD is polygenic (caused by multiple genes)
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Disadvantage of candidate genes as explanation of OCD?
number of candidate genes reduces usefulness of genetic explanation for OCD as it means each gene has small influence = unlikely to be helpful determining vulnerability and treatments
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Another disadvantage of candidate genes
purely genetic explanation ignores the role of environmental risk factors, which may be more important and useful to understand than genetic.
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Card 2


What are the 2 biological explanations?


Family Studies and Candidate Genes

Card 3


What are Family Studies?


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Card 4


What did Nestadt find?


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Card 5


What did Miguel find?


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