Biological approach to explaining OCD Flashcards
Biological approach to explaining OCD
list
Genetic explanations
Neural explanations
x
x
Genetic explanations
Parts
Candidate genes
Polygenic
Types of OCD
/ aetiologically heterogeneous
Candidate genes
└genes that create vulnerability for OCD
└some involved in regulating serotonin system
└e.g. 5HT1-D beta- efficiency of transport of serotonin across synapses
Polygenic
└several genes cause OCD
└Taylor (2013)-230 genes involved
└genes associated with mood regulating neurotransmitters (dopamine/serotonin)
Types of OCD
└aetiologically heterogeneous
└the origin of OCD has different causes
└different genetic variations= different types of OCD (e.g. hoarding/religious)
Genetic explanations
Strengths (1)
Good supporting evidence
└Nested et al (2010) reviewed previous twin studies
└68% of identical twins shared OCD
└31% of non-identical twins shared OCD
└=suggests genetic influence on OCD
Genetic explanations
Limitations (2)
Too many candidate genes
└although twin studies suggest OCD under genetic control
└can’t pin down all genes- genes only increase risk of OCD by a fraction
└=not useful explanation as little predictive value
Environmental risk factors
└diathesis-stress model- environmental factors can trigger the risk of developing OCD
└Cromer et al (2007)- over half OCD patients suffered trauma, OCD more severe if more trauma
└=OCD not all genetic- may be more productive to focus on environmental as we can do something about it
Neural explanations
└nervous system- brain structures/neurons
└neurotransmitters
Neural explanations
Parts
Role of serotonin
Decision-making systems
Role of serotonin
└neurotransmitter- responsible for relaying information between neurons
└low serotonin= transmission of mood relevant information doesn’t take place=mood effected
└OCD= low functioning serotonin system
Decision-making systems
└in particular hoarding disorder- impaired decision making
└abnormal functioning of lateral and frontal lobes
└frontal lobes- logical thinking
└left parahippocampal gyrus- associated with processing unpleasant emotions- functions abnormally
Neural explanations
Strengths (1)
Some supporting evidence
└antidepressants working on the serotonin system are effective in reducing OCD symptoms= suggests serotonin systems involved in OCD
└OCD symptoms form a part of a number of other conditions with biological origin- e.g. Parkinson’s disease (Nestadt et al 2010)= biological processes that cause symptoms of those conditions may also be responsible for OCD
Neural explanations
Limitations (1)
Can’t assume neural mechanisms cause OCD
└evidence that neurotransmitters and brain structures don’t function normally in OCD patients
└may be a result of OCD rather than the cause
