OCD Flashcards
What are the three different OCD characteristics?
Behavioural
Emotional
Cognitive
State the two examples of Behavioural OCD
Compulsions - performed to reduce anxiety created by obsessions
Avoidance - of anxiety-triggering situations
State two examples of Emotional OCD characteristics
Anxiety - obsessions and compulsions cause distress and worry
Guilt and disgust - due to awareness of excessive behaviour
State the two examples of Cognitive OCD characteristics:
Obsessions - recurrent intrusive thoughts or impulses that are seen as inappropriate and frightening or embarrassing to share.
Insight - people with OCD know their obsessions and compulsions are irrational, but they cannot help it
How do anti-depressants work?
They normalise the worry circuit by increasing serotonin levels.
They block serotonin re uptake in the brain, so it can continue to remained active (stimulate the post-synaptic neuron at the synapse, reducing anxiety).
How do anti-anxiety drugs work? Use benzodiazepines.
BZs slow CNS activity by engaging GABA activity, and GABA locks onto receptor sites outside the neuron.
This opens a channel to allow Chloride ions to flow into the neuron.
Chloride ions make it harder for the neuron to be stimulated by other neurotransmitters, slowing down activity and making the person relaxed.
What is the diathesis-stress model?
It brings nature and nurture together.
It suggests that genetic factors predispose an individual to developing OCD, but environmental factors trigger it.
Ocd is polygenic. What does this mean?
Caused by several genes, maybe up to 230, rather than a single gene.
What is the relationship between the COMT gene and OCD?
The COMT gene regulates dopamine function.
The COMT gene is mutated in OCD patients, and this variant decreases COMT activity. Therefore, there is a higher level of dopamine.
What is the relationship between the SERT gene and OCD?
Serotonin Transporter (SERT) genes appear mutated in OCD patients. This variant increases transporter proteins at a neuron’s membrane and leads to an increase in serotonin re uptake into the neuron. This decreases the serotonin level in the synapse.
Why might dopamine explain OCD?
Disrupted serotonin levels has a knock-on effect on regulating dopamine levels and other neurotransmitters.
Why might low serotonin cause OCD?
Low serotonin levels stop the normal transmission of mood-relevant information from taking place.
This can cause OCD.
Describe the worry circuit as a neural explaination for OCD:
Orbitofrontal Cortex (OFC) converts sensory information into thoughts.
It sends this information to the caudate nucleus (part of the Basal Ganglia). If the BG is damaged, irrelevant/unimportant information isn’t suppressed/ filtered as usual. So, it gets passed to the Thalamus instead which gets over-excited. Due to this, the Thalamus sends strong signals back to the OFC which interprets them.
Give a pro and con of anti-anxiety drugs:
PRO) Cheap, easily manufactured, affordable
CON) Symptoms not cause addressed… short term rather than longer term solution.
Side effects mean additional and unpleasant problems.
Give a pro and con of anti-depressants:
PRO) Cheap, easily manufactured, affordable
CON) Side effects cause additional and unpleasant problems
SSRI’s are more effective than placebos BUT 30-50% of OCD clients got no benefit.
Neural explanations for OCD revaluation:
Zohar et Al (1996) found that serotonin-increasing drugs are beneficial for up to 60% of OCD patients BUT most studies found 50% improvement of OCD symptoms with medication… suggests other factors are involved.
Serotonin reducing OCD symptoms does not mean it causes OCD.
Many OCD patients suffer depression, so this could be a reason for low serotonin rather than the OCD.
Antidepressants may effectively reduce OCD symptoms by….
…. normalising the worry circuit
What did MacGuire et Al (1994) find?
Sufferers of OCD were shown items designed to trigger obsessional thoughts during PET scans. OFC and caudate nucleus activity increased.
HOWEVER, this doesn’t mean that it causes OCD…. just associated with it.
Pauls et Al (1995) reported…
up to 10% of first degree relatives of those with OCD also developed the disorder.
Approximately 2% of the general population develop OCD.
So, OCD is far more likely to occur within families and so possibly genetic.
Alternative explanation for the finds of Paul’s et Al?
Family studies don’t control for environmental effects as relatives may have similar life events or learning experiences
Nestadt (2010) reviewed twin studies and found
… 68% of identical twins showed concordance for OCD compared to 31% in non-identical twins.
Why are concordance rates not 100% (ne Stadt)?
Other factors involved
