psychopathology - OCD Flashcards
what are the behavioural characteristics of OCD?
repetitive compulsions
compulsions reduce anxiety
avoidance
what are the emotional characteristics of OCD?
anxiety and distress
accompanying depression
guilt and disgust - directed at something external or the self
what are the cognitive characteristics of OCD?
obsessive thoughts - for 90% of people with OCD
cognitive coping strategies
insight into excessive anxiety
what did Lewis (1936) find?
observed that, of his OCD patients, 37% had parents with OCD and 21% had siblings with OCD
suggests that genetic vulnerability to OCD runs in families
what are candidate genes for OCD?
genes that create vulnerability for OCD
5HT1-D beta - serotonin receptor variant
SERT gene - affects the transport of serotonin
COMT gene - regulates dopamine
how is OCD polygenic?
many genes are involved
Taylor (2013) found evidence for up to 230 genes involved in OCD
- these genes are associated with the action of dopamine and serotonin
how is OCD aetiologically heterogeneous?
the origins of OCD vary from person to person
strength - what research support is there for the genetic explanation?
Nestadt et al (2010) reviewed twin studies
- 68% concordance rate for MZ
- 31% concordance rate for DZ twins
limitation - counter evidence for role of environment
Cromer et al (2007) found the over half the OCD patients in their sample had experienced trauma.
OCD was more severe in those with one or more traumas
how is the genetic explanation biologically reductionist?
ignores other factors in developing OCD, such as cognition
- can’t explain cognitive characteristics of the disorder, such as obsessive thoughts, which may make difficulties in treatment
how is serotonin involved in OCD?
serotonin regulates mood
OCD is associated with low levels of serotonin, which causes low moods
how is dopamine involved in OCD?
high levels of dopamine are associated with symptoms of OCD, such as compulsive behaviours
how are the lateral parts of the frontal lobes involved in OCD?
frontal lobes are responsible for logical thinking and making decisions
abnormal functioning of the frontal lobes causes impaired decision-making (this is most often seen in cases of hoarding)
how is the left parahippocampcal gyrus involved in OCD?
associated with processing unpleasant emotions
abnormal functioning can lead to emotional characteristics of OCD, such as guilt, anxiety, and distress
how is the basal ganglia involved in OCD?
involved in the coordination of movement
patients with injury in this area often develop OCD-like symptoms
how is the orbitofrontal cortex involved in OCD?
converts sensory information into thoughts and actions
PET scans have found higher activity in this area in patients with OCD
- this increases the conversion of sensory information to behaviours, which results in compulsions
- increased activity also stops patients from stopping the behaviours
strength - research support for neural explanation
antidepressants work on serotonin and are effective in reducing OCD symptoms
OCD symptoms form part of conditions known to be biological in origin (e.g Parkinson’s disease). From this we can assume the biological processes underlie OCD
limitation - why may the role of serotonin not be unique to OCD
many people with OCD experience co-morbidity as they also have clinical depression. The low levels of serotonin may simply be a result of the depression
limitation - how is the neural explanation biologically reductionist?
doesn’t take into account cognitive or behavioural factors.
some psychologists suggest OCD is learnt through classical conditioning and maintained through operant conditioning
- stimulus is associated with anxiety, maintained as the person avoids it and performs compulsive behaviours
how do SSRIs work?
selective serotonin re-uptake inhibitors
they prevent the serotonin from being absorbed into the presynaptic neuron. This increases levels of serotonin in the synapse and results in more being received by the postsynaptic neuron
why are SSRIs combined with other treatments?
often used alongside CBT
the drugs reduce emotional symptoms so the patient can engage more effectively with CBT
what are tricyclics?
second line of defence for people who don’t respond to SSRIs
older type of antidepressants
acts on various systems, including the serotonin system, which the same effect as SSRIs
e.g clomipramine (more serious side-effects)
what are SNRIs?
serotonin-noradrenaline reuptake inhibitors
second line of defence for people who don’t respond to SSRIs
different class of antidepressant drug
increase levels of serotonin and noradrenaline
what are benzodiazepines (BZs)?
anti-anxiety drug
enhance action of the neurotransmitter GABA, which tells the neurons in the brain to slow down and stop firing. 40% of neurons in the brain respond to GABA, so has a general quieting effect on the brain which reduces anxiety
