Biological Explanation for Explaining OCD

What is the genetic explanation for OCD

Individuals inherit specific genes that create a vulnerability to developing OCD

What does vulnerability mean in the genetic explanation of OCD

A predisposition to developing OCD

What does it mean that OCD is polygenic

OCD is influenced by many genes rather than one single gene

How many genes did Taylor identify as being involved in OCD

Around 230 genes

What does aetiological heterogeneity mean

Different combinations of genes may cause OCD in different people

What are candidate genes

Genes that create vulnerability to OCD

Which candidate gene is linked to high dopamine levels in OCD

COMT

How is the COMT gene linked to OCD

An abnormal variant is associated with high dopamine levels

Which OCD symptoms are linked to high dopamine levels

Compulsive behaviours

Which candidate gene is linked to serotonin levels in OCD

SERT

How is the SERT gene linked to OCD

An abnormal variant is associated with low serotonin levels

What symptoms are associated with low serotonin levels in OCD

Low mood and anxiety

What are neurotransmitters

Chemicals that send messages between neurons

How are dopamine levels linked to OCD

High dopamine levels are associated with OCD

How are serotonin levels linked to OCD

Low serotonin levels are associated with OCD

Which brain structure is associated with processing unpleasant emotions in OCD

The left parahippocampal gyrus

What is associated with abnormal functioning of the left parahippocampal gyrus

OCD

What is the basal ganglia

A cluster of structures involved in coordinating movement

How is the basal ganglia linked to OCD

Hyperactivity is associated with compulsive behaviour

What is the worry circuit in OCD

An overactive circuit involving the caudate nucleus orbitofrontal cortex and thalamus

Which brain structures form the worry circuit

The caudate nucleus orbitofrontal cortex and thalamus

What is a strength of the neural explanation for OCD

Supporting evidence from drug treatments

How do SSRIs support the neural explanation of OCD

They increase serotonin levels and reduce OCD symptoms

Why do SSRIs support the role of serotonin in OCD

Their effectiveness suggests low serotonin contributes to OCD

What is a strength of the genetic explanation for OCD

Supporting evidence from twin studies

What did Nestadt et al find about concordance rates for OCD

68 percent for MZ twins and 32 percent for DZ twins

Why do twin studies support a genetic explanation of OCD

MZ twins are more similar than DZ twins suggesting a genetic component

What is a limitation of the genetic explanation of OCD

The diathesis stress model suggests genes alone cannot explain OCD

Why does the diathesis stress model challenge a purely genetic explanation

MZ twins do not show 100 percent concordance rates

What does the diathesis stress model suggest about OCD

A genetic vulnerability is triggered by environmental stress

How does trauma support the diathesis stress model

Around half of OCD cases follow traumatic experiences

What is a limitation of the neural explanation for OCD

Issues with cause and effect

Why are cause and effect difficult to establish in OCD research

Most evidence is correlational

Why is correlational evidence a problem for neural explanations of OCD

It cannot show whether brain abnormalities cause OCD or result from it

What is a limitation of both neural and genetic explanations of OCD

They are biologically reductionist

Why are biological explanations considered reductionist

They oversimplify OCD by focusing only on biological factors

What does biological reductionism ignore

Cognitive emotional and environmental influences on OCD

How does CBT challenge purely biological explanations of OCD

Its effectiveness suggests there is a cognitive element to OCD

Name 2 strengths of biological explanations for OCD

Supporting evidence from twin studies and supporting evidence from drug treatments

Name 3 limitations of biological explanations for OCD

Diathesis stress model issues with cause and effect and biological reductionism