OCD

• Obsessions are recurring & persistent thoughts
• Compulsions are repetitive behaviours
• Behavioural characteristics of OCD are compulsions and avoidance
• Cognitve characteristics of OCD are obsessions, cognitive coping mechanisms, awareness of irrationality
• Patients often have family members with OCD, which supports the genetic basis
• Gene studies show that the COMT gene regulates dopamine, and the SERT gene regulates serotonin transport
• OCD is polygenic as it is caused by a combination of different genes
• Twin studies support the genetic basis for OCD
• Gerald Nestadt found that 68% identical twins shared OCD whereas 31% of non-identical twins did
• Environmental factors can also affect the development of OCD
• Kiara Cromer et.al. found that over 50% of OCD patients had experienced a traumatic event
• The neurotransmitters involved in OCD are serotonin and dopamine
• The Orbital Frontal Cortex (OFC) sends signals to the Thalamus about worrying things (obesessions)
• The Caudate Nucleus can inhibit signals from the OFC
• If worry signals get through the Thalamus is alerted which then sends signals back to the OFC (compulsions)
• OCD may be linked to CN underactivity or OFC overactivity
• SSRIs prevent reabsorption and breakdown to increase levels of serotonin in the synapse which then continues to stimulate the postsynaptic neuron which inhibits reuptake
• Tricyclics are an older form of antidepressant with the same effects as SSRIs but with more severe side effects
• Neurotransmitters are needed to help electrical signals cross the gap between neurons
• Serotonin diffuses across the synaptic gap to stimulate the postsynaptic neuron by binding with its receptors
• Serotonin is recycled by the presynaptic neuron in reuptake
• Anxiolytics are anti-anxiety drugs e.g benzodiazepines
• Benzodiazepines alter GABA receptor function so that GABA action in enhanced, which has a calming effect as neural signals are slowed down
• Drugs can be effective but will be more effective when combined with CBT
• The lower-activity version of the COMT gene means dopamine is less regulated leading to high levels of dopamine
• A mutation in the SERT gene causes low levels of serotonin
• There is evidence for brain differences for OCD e.g. Menzies
• Menzies conducted MRI scans of OCD patients and their families and found reduced grey matter in the region surrounding the OFC
• The DSM-5 categories of OCD are OCD, trichotillomania, hoarding disorder, excoriation disorder
• Emotional characteristics of OCD are anxiety, accompanying depression, guilt and disgust