ocd: neural explanation

Question 1

abnormal levels of neurotransmitters: serotonin

Answer 1

• serotonin regulates mood and lower levels of serotonin are associated with mood disorders such as depression.
• some cases of ocd are also associated with the reduced levels of serotonin, which may caused by the SERT gene.
• support for the role of serotonin in OCD comes from research examining anti depressants, which have found that drugs which increase the level of serotonin are effective in treating patients with OCD.

Question 1

abnormal levels of neurotransmitters: dopamine

Answer 1

• dopamine has been implicated in OCD, with higher levels of dopamine being associated with some of the symptoms, in particular the compulsive behaviours.
  this is based on animal studies where high doses of drugs were applied which induced stereotypical behaviours resembling compulsive behaviours.

Question 2

brain structure

Answer 2

• these abnormal levels of neurotransmitters may lead to abnormal functioning in certain parts of the brain. - the worry circuit
  1. the orbitofrontal cortex is involved in converting sensory info into thoughts
  example= you touch something dirty, and your thought is ‘ I am contaminated’
  2. the OFC sends this info to the caudate nucleus which normally suppresses or filters irrelevant or unimportant info.
  eg. your not contaminated, its fine.
  3. however, if it is damaged the message is passed to the thalamus which makes us take action, by sending signals back to the OFC.
  eg. wash our hands.

this creates a worry circuit.
inappropriate info is not suppressed and in the individual is overwhelmed.

Question 3

where is the worry circuit shown?

Answer 3

• in pet scans of people with ocd, taken while their symptoms are active. they show heightened activity in this area of the brain.
• it appears that serotonin and dopamine are linked to these regions of the frontal lobes. it is possible that abnormal levels of these cause them to malfunction.

Question 4

evidence

Answer 4

scans:
Menzies et al 2007 found that scans of people with ocd compared to non showed differences in the amount of grey matter in brain areas, including OFC, suggesting physical difference in areas implicated in this explanation.
- McGuire found that when shown objects that bring on their symptoms, activity increases in OFC and CN.

head injuries:
- the basal ganglia is a brain structure, involved in multiple processes, including coordination of movement. patients who suffer head injuries in this region often develop ocd like symptoms, following recovery.

Question 5

application

Answer 5

drug treatment:
if a therapy based on an explanation is effective, this provides good support.
eg. if outcome studies demonstrate that drugs are effective treatments, this provides a strong support for a bio explanation.
- Zohar et al found that drugs which increase serotonin have been beneficial for up to 60% of patients.
this supports the idea that low levels of serotonin may be associated with OCD.

two classes of drugs have proved effective: SRI’S AND SSRI’S. both inc serotonin levels.

CA= however, studies in which serotonin levels in obsessive disorder patients have been assessed has typically found no differences between them and healthy controls.

Question 6

S/W

Answer 6

:) scanning techniques used to measure brainnactvity of OCD patients provide the explanation with objective support, therefore giving scientific credibility.
:( difficult to establish whether the low levels of neurotransmitters cause ocd, are an effect of the disorder or are merely associated. causation cannot be inferred as only associations have been identified.
:( reductionist
reduces complex behaviour of ocd down to single components eg. neurotransmitters.
however, this can be useful on deciding on treatment
it is also a more complete explanation when we examine the link between neurotransmitters, brain structure and genes.

Question 7

alternative

Answer 7

cognitive explanation:
this centres on faulty information processing as being the root of disorder.