psychopathology-OCD Flashcards
what 3 symptoms is OCD characterised by
obsessions which lead to
guilt and anxiety which lead to
compulsions
what are obsessions and what do they lead to
disturbing recurrent thoughts which are not based on reality
they lead to guilt and anxiety
what are compulsions
repetitive behaviours that people feel an urge to do in order to reduce the feelings of guilt and anxiety
what is the behavioural characteristic of OCD
compulsions
a
they are external
what is the emotional characteristic of OCD
guilt and anxiety which may lead to depression
what is the cognitive characteristic of OCD
obsessions they may adopt cognitive strategies to deal with their obsessions
they are internal
what does the genetic explanation of OCD suggest
that we inherit OCD specific alleles on certain genes increase a persons risk of developing OCD.
what 2 genes affect OCD
-COMT
-SERT
OCD is polygenic
how does the COMT gene affect OCD
Lower activity of the COMT gene causes higher levels of dopamine
how does the SERT gene affect OCD
causes lower serotonin
how does the SERT gene cause lower serotonin
produces reuptake proteins that carry serotonin back into the pre-synaptic neuron so less is available at the synapse
-long allele produces more reuptake protein so less serotonin is available at the synapse so decreases inhibition of neural activity in post-synaptic neuron- so associated with OCD
what are the 2 pieces of supporting evidence for the genetic explanation of OCD
-Lewis
-Nestadt
what did Lewis find
examined patients with OCD
37% had parents with OCD
21% had siblings with OCD
what did Nestadt find
reviewed twin studies and found that
68% MZ twins shared OCD compared to 31% of DZ twins
big difference in concordance rates shows OCD is partially inherited
what are the limitations of twin studies
-assumes MZ and DZ twins have the same amount of shared environment -however MZ twins are more likely to be treated the same (as they look the same) than DZ twins
High concordance rate for OCD in MZ twins might be caused by shared environmental factors
what are some useful applications of the genetic explanation of OCD
led to the development of drug treatment as you can target the effect genes have on neural activity
It also helps support the biological explanation if OCD symptoms are reduced with SSRIs
who found supporting evidence for the use of drug treatments
soomro carried out a meta-analysis of 17 studies and found 70% of patients found an improvement with symptoms with SSRIs
what is an alternative explanation
the diathesis stress model-we have a genetic vulnerability which is switched on by a traumatic life event this explains why we don’t see 100% of people with the genetic default developing OCD
describe the neural explanation of OCD
Orbitofrontal cortex-detects a worrying stimulus and decides on an action
Sends this signal to motor cortex-controls movement
Basal ganglia-monitors outcome of actions sends inhibitory signals to orbitofrontal cortex to shut down worry signals
HOWEVER people with OCD have impaired communication between basal ganglia and orbitofrontal cortex
describe the signals from the basal ganglia to orbitofrontal cortex
Signals from basal ganglia to orbitofrontal cortex are much weaker so orbitofrontal cortex is less inhibited than it should be and neurons become hyperactive-generates OCD symptoms
Also when these signals are sent this leads to serotonin being released in the orbitofrontal cortex and neural activity is inhibited
HOWEVER people with OCD have lower serotonin levels so less inhibition of orbitofrontal neurons causing the neurons to become hyperactive
what is some supporting evidence for the neural explanation of OCD
-Max
-Saxena and Rauch
-Hu
what did Max find
studied a girl who had OCD after brain damage. Conducted an MRI and found she had damage to her basal ganglia
Suggests structural damage to the basal ganglia can cause OCD
what did Saxena and Rauch find
reviewed brain imaging studies comparing adults with and without OCD. They found an increase in activity in the orbitofrontal cortex with those with OCD suggesting hyperactivity in the OFC causes OCD
what did Hu find
compared OCD and non-OCD and found lower levels of serotonin in the OCD suffers showing low serotonin is associated with the onset of the disease.
why is this research correlational and not causation
-evidence to suggest OCD pateints have abnormal levels of Neurotransmitters are abnormal brain structure but this does not mean that this is what causes ocd so we cannot draw cause and effect conclusions.
What is an alternative explanation for OCD
The two process model
We can acquire ocd through classical conditioning eg pairing the dirt with anxiety
We can maintain ocd through operant conditioning
through negative reinforcement stimulus is avoided so anxiety is reduced
who found limitations for the neural explanation of OCD
Aylward-Found no difference between the basal ganglia of those with and without OCD. Structural damage to the basal ganglia and hyperactivity in the OFC may not be the only causes
state 2 drugs used to treat ocd
SSRIs
tricyclics
Explain how SSRIs work
block serotonin reuptake. More serotonin available at the synapse in the orbitofrontal cortex so more inhibition of neural activity In the orbitofrontal cortex reducing hyperactivity of neurons in this region which reduces worry signals that cause obsessions and compulsions
Explain how tricyclics work
Tricyclics block the transporter mechanism that reabsorbs both serotonin and noradrenaline so more is available at the synapse
State two pieces of supporting evidence for the biological treatment of OCD
-Soomro-70% of the adults with OCD who were treated with SSRIs noticed an improvement in symptoms
SSRIs are significantly more effective at reducing OCD symptoms than no treatment
-cost-effective compared to CBT (Cognitive behavioural therapy)
What are the limitations for the biological treatment of O C D
-Can cause side-effects
Soomro-found that patients treated with SSRIs experienced side effects eg-nausea
-if patients stop taking SSRIs they may relapse and symptoms may return
-may not be effective at treating the underlying cause of OCD
Eg-may not treat cognitive factors so may need to combine CBT with SSRIs
O’Connor-combing biological and cognitive treatment for OCD could be more effective
CBT and SSRIs showed the biggest improvement
