OCD Flashcards
What approach do we study in terms of OCD?
Biological (explanation)
What are the 2 different ways that biologists believe OCD is caused?
Genetic
Structural
How is the genetic theory tested?
Twin studies
How does twin studies support that it could be biological?
A study in 2005 showed that when 1 MZ twin has OCD there is a 53-87% chance that the other will develop it
DZ twins have a 22-47% chance
Why should MZ twins have a higher concordance rate than DZ twins?
They are genetically identical
What does this 2005 study suggest?
Suggests that genetic factors influence brain structure and neurochemistry.
What are gene-mapping studies?
Comparing the genes of an OCD sufferer to the genes of someone without OCD.
What does gene-mapping attempt to indicate?
Particular genes make some people more vulnerable to OCD.
What does polygenic mean?
That a combination of genes are responsible for causing a behaviour (E.G. OCD)
What gene is it likely to be?
The SERT gene
The COMT gene
What does the SERT gene do?
Transports serotonin throughout the body
Low lvls of serotonin seen in OCD sufferers
What does the COMT gene do?
Variation in the COMT gene affects dopamine lvls
Low lvls of dopamine seen in OCD sufferers
Are these genes beneficial?
Could be, to avoid germs
But could be bad, interferes with everyday life
What are the limitations with the genetic explanation?
Nobody know what is being inherited.
Never 100% concordance rate
Suggests that some OCD forms are more genetic in nature than others.
No single gene has been isolated, it is likely to be polygenic.
What does the structural explanation focus on?
Neurotransmitters
Brain structure
What are neurotransmitters?
They are chemical messengers that carry, boost and regulate signals between neurons. This affects moods.
What is a neurotransmitter linked to OCD?
Serotonin
In what year did someone find that low levels of serotonin are linked to OCD?
Hu in 2006
Does an increase in serotonin work for everyone?
NO, some people get worse
What does serotonin do?
Serotonin works in the orbito-frontal cortex and caudate nucleus. The low levels of serotonin may cause abnormal functioning in the areas of the brain linked to OCD.
What are the orbito-frontal cortex and caudate nucleus linked to?
Both parts of the brain are closely linked to impulsive behaviour
Where has a suggestion of a link come from between low levels of serotonin and OCD?
SSRIS, when taken people’s OCD has been seen to decrease.
Are low lvls of serotonin the cause of OCD?
NO, it just reduces the symptoms
What do SSRIs do?
They prevent serotonin being reabsorbed into the presynaptic neuron, causing it to cross the synapse and enter the postsynaptic neuron. T/F lvl of serotonin increase.
Which part of the brain could cause OCD if it has an abnormality?
Basal ganglia.
What is OCD often co-morbid with?
Tourette’s
Huntingdon’s
Parkinson’s
These ALL involve the basal ganglia
What are the 3 parts of the brain that are linked to OCD?
Orbito-frontal cortex
Thalamus
Caudate nucleus
What does the OFC do?
Notices when there is something wrong.
It is involved in behaviours, decision making
What does the thalamus do?
Directs signals from many parts of the brain to places that can interpret them.
What does the caudate nucleus do?
Regulates signals sent between the OFC and thalamus.
What research is there to back up the theory of brain structure?
Ursu and Carter- monitored brain activity of 15 ppl with OCD.
FMRI found hyperactivity in the OFC, so a lack of behavioural regulation could result in worry symptoms of OCD.
Describe a scenario where brain structure can cause OCD.
OFC notices that something is wrong (e.g. dirt), there is a worry signal sent to the thalamus
Thalamus is over excited and sends strong signals back to the OFC
Sends the signal back and forth. This explains why compulsions only give temporary relief.
Did the brain malfunctioning come first or was it the OCD?
