The biological approach to explaining OCD Flashcards
What is obsession and compulsions
Obsessions - persistent thought, cause of the anxiety -(internal component)
Compulsions - A repetitive behaviour that reduces anxiety temporarily - External component
What is OCD
An anxiety disorder where anxiety arises from the obsessions that lead to compulsions
What are the different types of biological explanations to OCD
Genetic explanations
neural explanations
What are the genetic explanations to OCD
SERT gene
COMT gene
OCD may be polygenic
What is the SERT gene in regards to OCD
Candidate gene
- Affects the transportation of the neurotransmitter serotonin
- Lower levels of serotonin is implicated in OCD (also linked to depression and anxiety)
What is the COMT gene
Candidate gene
- suppose to regulate the production of dopamine
- A variation in the COMT gene results in higher levels of dopamine this variation is more common in people with OCD
Why may OCD be a polygenic condition
May not be caused by one singular gene but by a combination of genetic variations that together increases vulnerability
Taylor (2013) found up to 230 different genes that could be involved in OCD
What the neural explanations of OCD
Roles of neurotransmitters
The worry circuit
What are the roles of neurotransmitters
Serotonin - Mood, wellbeing, Happiness
Dopamine - Addiction, motivation, repeat behaviours
You can have low or high levels of these without having the SERT or COMT gene
What is the worry circuit
- Caudate nucleus normally supresses signals from the orbitofrontal cortex (OFC) which can normally differentiate ‘major’ and ‘minor’ worries
- The caudate nucleus is often damaged in OCD patients
- When damaged the caudate nucleus fails to supress minor worries signals and the thalamus is alerted
- This creates a worry circuit
thalamus - Relay system and alerts the SNS
What do the components of the Worry circuit do
Caudate nucleus - Normally suppresses signals from the OFC
Orbitofrontal cortex - Differentiates major and minor worries ]
Thalamus - Relay system that alerts the SNS
What can you use to evaluate the biological approach to OCD
- Research support - Family studies
- Twin studies
- Issues with Cause and effect with neural explanations
- Alternative explanations - cognitive approach
How would you evaluate the behaviourist approach to OCD by
- Research support from family studies
Lewis - examined patients with OCD and found 37% had parents with OCD and 21% had siblings with the disorder
Another psychologist took this point further and shown patients who have a first-degree relative (50% shared DNA) are 5x more likely to get ODC
supports genetic factors playing a role but doesn’t rule out situational factors
How would you evaluate the behaviourist approach to OCD by
- Twin studies
14 Twin studies shown monozygotic twins (100%) have double the risk of having OCD if one twin has OCD compared to dizygotic twins (50%). supports that the biological approach and the genetic inheritance
However concordance rates are never 100% so there must be other factors affecting OCD. So the diathesis stress model may be a better explanation since not all identical twins both have OCD if one does
How would you evaluate the behaviourist approach to OCD by
- Cause and effecting in neural explanations
Cause and effect cannot be established
. difficult to establish whether the damaged caudate nucleus is the root cause or it is a symptom due to brain scanning being retrospective (after diagnosis)
. Also not all OCD patients have a damaged caudate nucleus
Hard to tell if the biological abnormalities are the cause of OCD or are just symptoms
How would you evaluate the behaviourist approach to OCD by
- Alternative explanations (cognitive approach)
The 2 process model proposed by behaviourists challenges the biological approach
- The a acquiring of the irrational thought/a fear stimulus through classical conditioning e.g. Dirt is associated with mud
- The behaviour is maintained through operant conditioning and negative reinforcement where the act of the compulsions (e.g. washing hands 5 times) reduces the anxiety and irrational thought maintaining the irrational thought
behavioural treatments for OCD are 60-90% successful in adults
What does the biological treatments for OCD aim to do
Aim to restore neurochemical imbalances in the brain since this is assumed to be the the main cause of OCD
What 2 drugs can be used to treat OCD
Antidepressants (SSRI’s)
Anti-anxiety Drug (BZ’S): Benzodiazepines
What are SSRI’s and what is the dosage
Selective serotonin reuptake inhibitor
(sertraline, Prozac)
Dosage: Taken via tablet form usually 50-200mg. Usually taken for approx. 3 months before symptoms are elevated
What do SSRI’s do and how do they do it
. They increase the levels of serotonin by preventing it from going back into the pre-synaptic neuron (works on pre-synaptic neuron)
- They increase the level of serotonin in the synapse by inhibiting it from being reabsorbed into the pre-synaptic neuron.
- The serotonin can therefore continue to stimulate the post-synaptic neuron and more serotonin is transported into the neuron increasing serotonin levels
What do BZ’s do and what is the dosage
BZ’s are commonly used to reduce anxiety (Anti-anxiety drugs). They slow down the central nervous system by enhancing the activity of the neurotransmitter GABA. GABA when released has a calming effect .
Dosage: 2-10mg tablet that give an immediate effect
However they are short term usually 4 weeks sue to risk of addiction.
How do BZ’s work
BZ’s lead to a release of GABA (works on the post synaptic neuron)
- GABA when released locks on to GABA receptor sites located on the post synaptic membrane/neuron
- When GABA locks onto these sites it opens a channel which increases the flow of Chloride Ions making it difficult for the post-synaptic neuron to be further stimulated by another neurotransmitter (e.g. dopamine)
Chloride ions are negative so also give a calming effect
How would you evaluate the biological treatments to OCD
+ Cost effective and non-disruptive
+ Effective at tackling OCD
- side effects
- They treat the symptoms not the cause
How would you evaluate the biological treatments to OCD
+ effective at tackling OCD
Clear evidence of SSRIs in reducing the severity of OCD
- Soomro et al found SSRI’s were more effective than placebo drugs in 17 different drug trials and that symptoms reduced around 70% when taking SSRI’s
- Strength : improves quality of life for OCD patients
- Weakness : studies only look at short term effectiveness not long term
How would you evaluate the biological treatments to OCD
+ Cost effective and non-disruptive
They are cheap compared to other psychological treatments
- For example CBT as in CBT you have to pay for therapists and sessions but you don’t for drugs
This means its good value for the NHS and the economy
Also they are non-disruptive and ‘passive’ to daily life - meaning people don’t need to re-live trauma or need the motivation to go through CBT and with taking a tablet they can get on with their daily lives
How would you evaluate the biological treatments to OCD
- Drugs can have side effects
Although the drugs can significantly improve the symptoms of OCD, some people will see no benefit due to side effects
- SSRI’s can give side effects such as headaches, indigestion, irritability
- BZ’s can give even more severe side effects
This is problematic as if the side effects of the drug are worse than the symptoms of the OCD patients will stop taking the drug therefore relapse rates (attrition rates) will increase
How would you evaluate the biological treatments to OCD
- Drugs treat the symptoms but not the cause of the OCD
- Drug treatment such as SSRI’s and BZ’s simply reduce the symptoms of OCD
- For example BZ’s don’t uncover the root cause of the OCD but are only taken for approximately 4 weeks therefore they aren’t long term
- This means that when patients stop taking the drugs there is a chance they will relapse
- Showing drugs may not be effective on their own and may be better alongside CBT
