Psychopathology - Biological approach to OCD Flashcards
What are the general assumptions of the biological approach to OCD?
(NAGI)
- OCD is caused by neural abnormalities in the
structure or function of the brain - OCD may be partly caused by genes
- OCD is assumed to be an illness which can
be treated medically
(Neural Abnormalities Genes Illness)
How is OCD thought to be linked to neural abnormalities in the brain?
- evidence that OCD is linked to abnormalities in brain circuits that are involved in detecting & responding to potential danger
- in OCD it is thought that abnormal activity in
these circuits may trigger obsessions &
compulsions
How is are the Basal Ganglia & Orbito Frontal Cortex thought to be involved in OCD?
- The two areas of the brain connect in a circuit
which is responsible for detecting &
responding to threats - Abnormalities in this circuit may mean that
there is overactivity of primitive, protective
behaviours - over activity of direct pathway triggering
concern about danger, harm & hygiene - under activity of indirect pathway which
inhibits compulsive behaviour (behaviour
becomes repetitive)
Evidence for neural abnormalities & OCD
- brain scanning studies of patients with OCD
has revealed abnormalities in basal ganglia
(but NOT all OCD patients) - symptoms of OCD can be reduced by altering
the activity between the O.F.Cortex & BG
(deep brain stimulation)
Damian Denys
- DBS effective in 60% of OCD patients
Polak: Case Study
- man who suffered damage to BG after heart
attack showed compulsive whistling
behaviour
Weaknesses of using neural abnormalities to explain OCD
- we cannot be certain of cause & effect from
brain scanning studies
(abnormalities may be a result of OCD) - Scanning studies have not found
abnormalities in brain function in every
patient with OCD
> other explanations are needed
What are neurotransmitters & how are neurotransmitters thought to be involved in OCD?
- Chemicals in the brain that allow messages
to be sent between brain cells - Serotonin = involved in mood regulation
- one theory is that OCD is related to reduced
activity of serotonin in the brain
Evidence for mutations in neurotransmitters & OCD
- mutations in a gene linked to serotonin
activities have been found in brain scanning
studies comparing patients with & without
OCD - considerable evidence for medications that
increase Serotonin activity being effective in
reducing OCD symptoms
Weaknesses of neurotransmitter abnormalities explaining OCD
- The brain uses a complex range of
neurotransmitters which interact with each
other. It is unwise to focus on the role of one - Drug effectiveness does not prove a cause -
may be treating symptom - Improvements in OCD patients have been
found in those treated with SSRIs &
psychologically (Baxter)
> brain abnormality may be a consequence
not cause of OCD
Why are genes thought to be involved in OCD?
- evidence that OCD ‘runs in families’
- we may inherit a vulnerability to OCD
- twin studies support the idea of a genetic
component
What does polygenic mean?
linked to many genes NOT a single gene
Evidence for role of genes in OCD
Nestadt:
- review of evidence from twin studies found a
concordance rate of 68% for identical (MZ) &
31% for non-identical (DZ)
- Identical twins more genetically similar so
suggests genetic component of OCD
Van Grootheest:
- review of twin studies found that OCD has a
stronger genetic component if people
develop it in childhood
- suggests environmental triggers may cause
some adults to develop OCD without genetic
vulnerability
Gene mapping (NIMH America)
- OCD linked to serotonin transporter gene
(SERT) which is important in how serotonin in
transported across synapses
Zohar
- drugs that reduce serotonin levels cause an
increase in OCD symptoms
- drugs that increase ser. levels have been
found to reduce symptoms
Weaknesses of the use of genes to explain OCD
- NO twin study of OCD has found 100%
concordance rate - although MZ & DZ twins raised together,
upbringing of MZ twins may be more similar - The mechanisms by which genes make
someone more vulnerable to OCD aren’t
currently fully understood - role of genes so complex that we are unlikely
to find a clear treatment
What are examples of biological treatments of OCD?
- drugs (SSRIs = Serotonin re-uptake inhibitors)
- surgery (Deep Brain Stimulation (DBS))
How are SSRIs used in the treatment of depression & how do they work?
- 20mg a day
- 3-4 month course of treatment
- prescribed
- drugs reduce the re-uptake of serotonin,
making more available in the synapse
What are some side effects of SSRIs?
- tiredness
- sleep disturbance
- headaches
- suicidal thinking
Evidence for the effectiveness of SSRIs
Soomro:
- review found that SSRIs were better at
treating OCD and were moderately effective
at reducing symptoms in adults
- estimated around 70% of patients show
significant reduction in symptoms
(BUT be wary of drug company bias)
Koran: combining SSRIs with other medication
- patients varied in how well they responded to
SSRIs combined with olanzapine
- there appeared to be benefits of trying
combination with patients who didn’t respond
to SSRIs alone but considerable weight gain
Why might SSRIs be seen as an appropriate OCD treatment?
- reduction in symptoms can reduce distress &
improve wellbeing - benefits the economy if people can return to
work (no sick leave) - relatively ‘cost effective’ - tablets cheaper to
NHS than cognitive therapy sessions & no
time off work needed - tablets can be taken easily
Why might SSRIs be seen as an inappropriate OCD treatment?
- can have unpleasant side effects - people
may drop out of treatments needing
alternative therapy - people’s symptoms may return if they stop
taking the medication - some people take
medication for many months or years (may be
more effective to combine medication with
cognitive therapy to help) - Fluoxetine is not appropriate for young
children as it’s use has been associated with
thoughts of self harm or suicide
What is deep brain stimulation (DBS)?
- surgery involving inserting an electrode into
the area of the brain thought to be
malfunctioning - the electrode sends impulses to these areas
& remains in the brain
Evidence for DBS as a treatment for OCD
Damian Denys:
- 60% of 50 patients treated with DBS to basal
ganglia area found improvements in OCD
symptoms
Problems with DBS as an OCD treatment
- 40% Denys’ patients didn’t significantly
improve - complex & dangerous - high risk of internal
bleeding - used in intractable cases of OCD (last resort)
