OCD - Biological

What is the DSM definition, what is obsession and complusions?

characterised by obsessions and/or compulsions

obsession- recurring thoughts

compulsions- repetitive behaviours

What are behavioural characteristics of OCD?

• repetitive compulsions to reduce anxiety

• avoidance from situations which trigger OCD = avoiding normal situations

What are emotional characteristics of OCD?

• anxiety and distress

• sense of fear can be overwhelming, often a result of obsessive thoughts and cause people to fulfil compulsions

• depression- accompanied by low mood and compulsive behaviours( only bring small temporary relief)

• guilt and disgust directed at themselves or externally

What are cognitive characteristics of OCD?

• obsessive thoughts

• repetitive, intrusive thoughts

• cognitive strategies to deal with obsessions - coping mechanisms

• insights into excessive anxiety

• sufferers aware their thoughts aren’t normal

• necessary for OCD diagnosis- otherwise suffers from delusional thoughts

What does OCD being polygenic mean?

not caused by one single gene, up to 230 different genes potentially involved

What are candidate genes?

genes that create vulnerability to OCD that we inherit

37% had OCD 21% had siblings with OCD

What are SERT genes

linked to serotonin and effects transport of this neurotransmitter, transport issues can cause lower levels of serotonin (depression)

What are COMT genes?

regulate neurotransmitters of dopamine so if have gene = higher levels of dopamine = more likely of OCD

Explain serotonin

regulate moods

• unable to regulate mood

• mood and mental state - higher anxiety = compulsions, used to control anxiety

What is the basal ganglia

• cluster of neurons at the base of forebrain

• involved in coordination of movement

• if you suffer a head injury = OCD-like symptoms

What is the orbitofrontal cortex

• converts sensory information into thoughts and actions

• PET- higher activity in OC in OCD patients

• higher activity = higher conversion

How do SSRI’s work?

• serotonin is released by presynaptic neurons and travel across a synapse

• leftover serotonin is normally reuptaken or broken down by enzymes

• SSRI’s prevent serotonin being reuptaken, so there is more serotonin that binds to receptors

• higher serotonin levels in patients

How do they help treat OCD?

• helps manage symptoms as they are able to better manage their mood therefore patients do not feel the need to perform compulsions to manage this

How long do they need to be taken for and how are they used alongside other treatments

2-4 weeks of daily use to have impact

Tricyclics - same effect on serotonin system as SSRIs

• more severe side effects than SSRIs so more generally kept in reserve for those who do not respond to SSRIs