OCD Flashcards
Describe the background to OCD.
- 1-2% of the population
- Experience intrusions and anxiety which cause patient to perform compulsions to relieve anxiety.
- Can be measured using the Yale-Brown Obsessive Scale
Show how a stimulus becomes attached to a ritual in OCD.
STIMULUS
- > obsession
- > Distress and anxiety -> ritualised behaviours (compulsions) —–positive feedback & reinforcement—> temporary relief from distress and anxiety
What 2 treatments are used for OCD?
- Selective Serontonin Reuptake Inhibitors (SSRIs)
- CBT
What is the discrepancy of treating OCD with SSRIs?
It is unclear if OCD or depression is being treated as the medication is used for both disorders.
What circuit is implicated in OCD and how?
- Cortical-Striatal-Thalamic Circuit
- OCD only uses the direct pathway, not the indirect.
- Direct pathway: OFC + ACC -> Striatum -> GPi + SNr ->Thalmus -> beginning
- Excessive activity of direct pathway = hyperactivation of orbitofrontal-subcortical pathway
What affect does the OFC have on cognition?
It creates exaggerated concerns about danger/hygiene/harm. Persistent conscious attention to threat and mentalising threat.
Damage to what area causes a decrease in OCD symptoms?
Frontal cortex near the ACC
What positive correlation has been found in the OCD brain by Atmaca et al. (2007)?
- Positive correlation of Y-BOCS and OFC/thalamusMRI - - - ROI volumetric analysis
- Increased white matter
- Smaller OFC volumes
- Bigger thalamus volumes
What 3 areas decreased in grey matter in Pujol et al. (2004)?
- MRI mapping
- Decreased grey matter in 3 areas: medial frontal gyrus, medial orbitofrontal cortex, left insulo-opercular region
- Bigger ventral striatum
- Disease severity/nature of symptoms/comorbidities not related to changes
What are the 5 main brain areas affected in OCD?
- Increase white matter
- Increased ventral striatum
- Increased thalamus
- Decreased OFC
- Decreased frontal cortex
What did Harrison et al. (2013) state about functional connectivity in OCD?
Strength of functional connectivity between the ventral striatum and anterior orbital frontal cortex predicted total Y-BOCS.
- increased correlation of frontal cortex and striatum = increased symptoms
Where can DBS be used to decrease OCD and how?
Bilateral in the ventral striatum: reduces connectivity of ventral striatum and lPFC/mPFC leads to reduction in symptoms
What is the success rate of DBS?
- 60% of responders have an 80% reduction in symptoms
What did Krutson et al. (2001) find about reward processing in OCD?
- Reward task and the Basal Ganglia
- Monetary Reward Relay Task with fMRI
- Nucleus accumbens was less activated in OCD (DBS counteracts this)
What does the Stroop Task (Gehring et al., 2000) show about OCD?
That OCD patients have a bigger Error Related Negativity Response, even with no difference in behavioural performance
Where are hyperactive error signals found in OCD?
Frontal-striatal-thalamic circuit: medial frontal action monitoring is seen as the source of error signals
What could be used as a trait marker of OCD?
Overactive performance monitoring
Which is the best treatment for OCD: CBT or anti-depressants?
CBT (Ost et al., 2015)
What did de Vries et al. (2014) suggest could be an endophenotype of OCD?
- Working memory task and fMRI
- Patients, controls and siblings
- Siblings had to use more activation to score same as controls
- Hyperactivation of fronto-parietal circuit = endophenotype of OCD?
What did Harrison find about some areas of the brain and symptom dimensions of OCD?
- Corticostriatal functional systems mapped with OCD symptoms
- Symptom dimensions match specific areas of the brain
- Aggression and ventral striatum
What did Figee et al. (2014) find about DBS?
- DBS reduced excess connectivity between the nucleus accumbens and PFC
What did Riesel et al. (2010) find in first-degree relatives?
- increased ERN reponse like OCD patients
- Over-active monitoring = trait marker for OCD
