Bio and OCD

Report
Biological theories of atypical
behaviour
0 The basic view of the biological approach is that
things go wrong with thinking, emotion and
behaviour because things have gone wrong with the
brain:
0 One or more parts is abnormally structured
0 One or more parts is functioning abnormally (i.e. too
active or not active enough)
Biological theory of OCD
Orbitofrontal
cortex
Thalamus
Brain activity in OCD patients
Orbitofrontal
cortex
Genetics
0 How can genetic links be researched?
0 Family studies
0 Twin studies
0 Adoption studies
Genetics
0 Family studies – relatives of OCD sufferers have a
higher prevalence of OCD than the general population
(Nestadt et al, 2000)
0 Twin studies – a review of 14 published twin studies
into OCD found 54/80 concordance for MZ twins and
9/29 DZ twins.
AO2 (However…)
0 We can’t completely eliminate
the influence of the
environment in twin and family
studies.
AO2 (However…)
0 Gene therapy is very new.
0 Anthropomorphism!
An “OCD gene”?
0 Sapap3 – a gene expressed in
the striatum, which controls
processes such as planning and
action has been implicated in
OCD. Feng et al (2007) found
mice lacking the gene showed
high levels of anxiety and pulled
out their own fur. When given
the sapap3 protein however, the
symptoms disappeared.
Biochemical Research
0 Pigott et al (1998) found drugs which increase serotonin
reduce OCD symptoms (eg SSRIs used for treating
depression)
0 In comparison, antidepressants which do not affect
serotonin do not reduce OCD symptoms (Jenicke, 1992)
0 Comer (1998) suggests that serotonin plays a key role in
the functioning of the OFC, therefore low serotonin = poor
functioning.
0 Animal studies have found that high levels of dopamine
could link to OCD, where enhancing dopamine levels
resulted in OCD-like behaviour (Szetchman et al, 1998)
AO2 (However…)
0 The link is not straightforward, particularly is
serotonin is an effect of OCD and not a cause.
0 Insel (1991) found that drugs only partially relieve
the symptoms.
0 Other research does support the link however. For
example Kim et al (2007) found SSRIs which raise
serotonin, reduce dopamine and this reduction was
positively correlated with a reduction in Y-BOCS
scores.
Neuroanatomical factors
0 Genetic factors may affect the brains’ structure.
0 Research suggests the following areas are implicated
in OCD:
- basal ganglia
- orbito-frontal cortex (OFC)
- the caudate nucleus
- the thalamus
0 Read through pages 379-80 and note down a piece of
evidence to support or an example to explain their
involvement.
0 Include notes on the Menzies et al (2007) study.
AO2 (However)
0 Not entirely sure what the
causal factor is in these
cases (i.e. genetic or
abnormalities).
0 Doesn’t necessarily help
with treatments.
Evolutionary approach
0 OCD could be seen as adaptive:
- Grooming behaviour (OCD
patients often wash and
groom)
- Concern for others (OCD
patients are often concerned
with harming or embarrassing
others)
- Hoarding (OCD Patients might
hoard collections)
0 How might these things be
seen as adaptive?
Evolutionary Approach
0 Abed and de Pauw (1998) suggest a mental module
for OCD, which has evolved over time.
0 They call it the Involuntary Risk Scenario Generating
System (IRSGS), where individuals are able to evaluate
risk before engaging in behaviour.
0 They suggest OCD sufferers may have an overactive
IRSGS.
AO2 (However)
0 The mental module idea creates some testable
hypotheses according to Abed and de Pauw (1998),
which has been supported by others. For example,
OCD patients should be less prone to risk taking
because the IRSGS alerts them to the dangers.
0 Other evidence comes from research into increased
OCD symptoms during times of increased risk (e.g.
during pregnancy). Buttolph et al (1998) found this to
be the case where OCD was higher during pregnancy.
Past paper question
0 Discuss two or more biological explanations of OCD
(8 marks + 16 marks)
0 Using the research covered so far, work out a plan in
response to this question.
0 Try and make the links between ideas and statements
clear in your plan.
Biological Treatments
0 Biological responses to OCD mainly focus on:
- Drugs (chemotherapy)
- Psychosurgery
Drug treatments
0 As discussed, there is evidence to suggest that drugs
which raise levels of serotonin can help with OCD.
Anti-anxiety drugs
0 Benzodiazepines (BZs) are commonly used to reduce
anxiety (e.g. Valium, Xanox and Diazepam). They slow
down the nervous system by increasing GABA, a NT
which quietens the neurons in the brain, by reducing
stimulation.
AO2
0 There is lots of evidence to support the use of SSRIs in
treating OCD (see previous notes)
0 Side effects – using a tricyclic antidepressant like
clomipramine leaves greater side effects, but there is
some evidence to show it is a helpful in treating OCD.
0 Treatment aetiology fallacy – just because the
symptoms disappear, doesn’t mean the cause has
been treated. There is a higher relapse rate in OCD
patients who start a drug treatment compared to
psychological treatments.
Psychosurgery
0 This refers to surgical intervention to relieve
symptoms of OCD. It may involve removal or
disconnection of brain regions responsible. In this
case the capsule and cingulum are implicated (part of
the limbic system).
Psychosurgery
0 Using p384 in the blue
textbook, note down what
transcranial magnetic
stimulation involves as a
method of psychosurgery.
AO2
0 Dougherty et al (2002) found that up to 45% of patients
0
0
0
0
studied who had been unsuccessfully treated with drugs
showed improvement after cingulotomy.
Jung et al (2006) supports this with no adverse side effects.
However, Koran et al (2007) suggests the results may be
biased as patients know they are being treated (i.e. placebo
effect).
Greenberg et al (1997) used TMS for 20 mins on frontal sites
to treat patients and found a reduction in compulsive
behaviour which lasted for 8 hours.
However, Rodriguez-Martin et al (2003) found that an
experimental TMS group compared to a placebo TMS group
showed no significant reduction in OCD symptoms.
Past paper question
0 Discuss two or more biological therapies for OCD (9 +
16 marks)
0 Write a detailed plan OR have a go!

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