Psychopathology - OCD Flashcards
what is diathesis stress?
the idea that genes are not directly causing complex disorders - the environment will affect whether the disorder is developed or not as well
what are obsessions in OCD?
repeated intrusive thoughts that can be calmed by compulsions
what are compulsions in OCD?
repetitive behaviours that calm the anxiety caused by obsessions
what are the biological explanations of OCD?
neural explanations
genetic explanations
what is the neural explanation for OCD?
OCD occurs because of abnormal levels of neurotransmitters and abnormal brain circuits
how can abnormal levels of neurotransmitters cause OCD?
people with OCD have abnormally high levels of dopamine and abnormally low levels of serotonin
what are the functions of dopamine?
waking up, movement, memory, rewards
main function habit forming
which areas of the brain is dopamine mainly released into?
emotional, executive and memory
what are the functions of serotonin?
appetite, mood
main function is impulse control
is dopamine an excitatory or inhibitory neurotransmitter?
excitatory
which areas of the brain is serotonin mainly released into?
emotional, memory and muscle control
is serotonin an excitatory or inhibitory neurotransmitter?
inhibitory
how can abnormal brain circuits help to cause OCD?
when damaged, the OFC - thalamus - caudate nucleus cycle can cause OCD
what is the OFC - thalamus - caudate nucleus circuit in a healthy brain?
OFC - sends signals to the thalamus about things that are worrying
thalamus - causes impulses to act and to stop acting once OFC stops sending signals
caudate nucleus - suppresses signals from the OFC
what is the OFC - thalamus - caudate nucleus circuit in a damaged brain?
OFC - sends signals to thalamus about worrying things
Thalamus - leads to impulses to act until no more signals from OFC
Caudate Nucleus - doesn’t supress signals from OFC so thalamus acts on minor worries, also sends signals back to the OFC, creating a ‘worry circuit’
what is the genetic explanation to the causes of OCD?
COMT and SERT genes contribute to development of OCD
what is the function of the COMT gene?
produces an enzyme that degrades dopamine
how is the COMT gene linked to OCD?
a low activity form of the gene is found in OCD patients
less dopamine broken down so more builds up in the synapses, especially after stress
what is the function of the SERT gene?
produces a protein that transports serotonin back to the presynaptic neuron in reuptake
how is the SERT gene linked to OCD?
high activity variant found in OCD patients
removes serotonin too quickly so less received by next neuron, so has less effects
how does the COMT gene and high dopamine levels directly cause obsessive thoughts?
COMT activity low
dopamine levels high
caudate nucleus overactive
hypervigilance (anxiety)
obsessive thoughts
how does the SERT gene and low serotonin levels directly cause compulsive behaviour?
SERT activity high
serotonin levels low
OFC underactive
impulsiveness
compulsive behaviour
what are some advantages of the biological explanation for OCD?
lead to successful treatments - SSRIs and BZs
fMRIs give reliable and objective evidence
what are the disadvantages of the biological approach to OCD?
reductionist and determinist - needs stress to kick off condition
problems with treatments such as SSRIs + BZs - side effects
CBT also good treatment
correlation vs causation
