Biological approach to OCD Flashcards
two explanations
genetic & neural
two genes
comt & sert
comt gene
- regulates dopamine production
- higher dopamine levels in OCDers
- szechtman et al (1998) = rats with increased dopamine performed ritual-like behaviours
sert gene
- regulates serotonin
- lower levels in OCDers
diathesis stress
- OCD doesn’t affect whole families so must be additional factors too
- this model suggests people gain OCD vulnerability through genes but an environmental stressor is required
neural explanation
- orbitofrontal cortex sends ‘worry’ signal to the thalamus
- normally suppressed by caudate nucleus but if this is damaged the thalamus is alerted & confirms the worry to the OFC
- creates a worry circuit
EVALUATION - genetic support
FAMILY STUDIES
- 80 patient study found having a first-degree relative with OCD increases risk 5X
TWIN STUDIES
- billet (1998) = MZ twins 2X likely to have it if co-twin has it than DZ twins
- but not 100% concordance so raises issues
EVALUATION - genetic limitation
NOT EXCLUSIVE TO OCD
- pauls & leckman = identified same gene in tourettes
- cross over symptoms with autism, anorexia nervosa & depression
- so it’s unclear
EVALUATION - support for neural
BRAIN SCAN SUPPORT
- OFC in heightened activity when symptoms are active
- BUT correlational so maybe altered NT levels cause this
- AND menzies (2007) = MRI showed reduced grey matter in the OFC & went on to show this was inherited
3 meds to treat it
- SSRIs (selective serotonin reuptake inhibitors)
- TCAs (tricyclic antidepressants)
- benzodiazepines
how do SSRIs work & success
- increase serotonin by blocking its reabsorption into nerve cells
- 40-60% success rate
SSRIs side effects
- nausea
- headaches
- insomnia
- sexual dysfunction
- rare = suicidal thoughts
how do TCAs work & success
- increases serotonin & affects other NTs like norepinephrine
- 50-70% success rate
TCA side effects
- blurred vision
- constipation
- drowsiness
- weight gain
- can increase risk of heart problems
how do benzodiazepines work & success
- enhances effects of GABA giving a calming effect - manages anxiety accompanying OCD
- doesn’t address core symptoms & only ST relief
BZ side effects
- drowsiness
- dizziness
- memory problems
- aggression
- confusion
EVALUATION - support for drug therapy
RESEARCH SUPPORT
- soomro et al (2008) = meta analysis found SSRIs were sig more effective than placebos over 17 trials
- BUT only focus on ST effectiveness
CHEAP
- cost effective compared to CBT, especially for those who lack motivation
EVALUATION - drug therapy limitations
SIDE EFFECTS
- worth the pros?
TREATING SYMPTOMS
- and not the cause
- once they stop taking it they are prone to relapse
- CBT has less chance of relapse
EVALUATION - neural limitation
cause & effect in brain scans
