Biological Approach And Treatment Of Ocd Flashcards
What are the two types of biological explanations for OCD
-Genetic
-Neural
What is a candidate gene
-A gene that creates a genetic vulnerability for a disorder. In this case the disorder would be OCD
Name two candidate genes
-The SERT gene
-The COMT gene
What is the SERT gene
-A candidate gene that affects the transportation of serotonin, resulting in lower levels of serotonin.
Are low levels of serotonin more common in people with OCD
YES. (Can also be linked to depression)
What is the function of the neurotransmitter serotonin
-Affects mood and calms the brain
What is the COMT gene
-A candidate gene that regulates the production of dopamine. However, a variation of the COMT gene results in higher levels of dopamine. This variation is more common in patients with OCD.
Function of dopamine
-A neurotransmitter that is responsible for motivation
Research that suggests that OCD may be a polygenic condition
-Taylor (2013) found that up to 230 genes may be involved in OCD.
This means that OCD may not be caused by one single gene but instead a combination of genetic variations that together significantly increase vulnerability to inherit OCD
Genetic explanations of OCD
-Candidate genes : COMT and SERT gene
-OCD may be a polygenic condition
Neural explanations of OCD
-The role of neurotransmitters : Serotonin and dopamine
-The Worry circuit
How may serotonin play a role in the development of OCD
-Neurotransmitters are responsible for relaying information from one neuron to another
-For example if a person has low levels of serotonin then normal transmission of mood relevant information does not take place and mood is affected (sometimes other mental processes too).
-Low levels of serotonin, which are associated with low mood, are more common in patients with OCD, suggesting that low serotonin levels may cause OCD
How may the worry circuit explain OCD
-The worry circuit is a network of brain regions that operate to alleviate worries. this includes regions such as the caudate nucleus, orbitofrontal cortex and the thalamus.
-The caudate nucleus helps filter out irrelevant thoughts and impulses received by the orbitofrontal cortex. -
-However, damage to the caudate nucleus can result in an inability to dismiss intrusive thoughts, leading to persistent worries and obsessions. This may cause individuals to engage in compulsive behaviors more frequently, as they may feel compelled to perform certain actions to alleviate anxiety.
-A damaged caudate nucleus is very common in patients with OCD, suggesting that it may cause OCD
What is the worry circuit
-The worry circuit is a network of brain regions that operate to alleviate worries. this includes regions such as the caudate nucleus, orbitofrontal cortex and the thalamus.
-The caudate nucleus helps filter out irrelevant thoughts and impulses received by the orbitofrontal cortex.
What did Lewis find about OCD in his family studies
-Lewis examined patients with OCD and found that 37% of patients with OCD had parents with the disorder and 21% had siblings who suffered.
What did Nestadt find about OCD in her family study
-Individuals who have a first degree relative with OCD are up to 5X more likely to develop the disorder over their lifetime, compared to those without this genetic link.
What did Billett find about OCD in his research on twins
-Conducted a study consisting of 14 pairs of twins, finding that monozygotic twins had double the is of developing OCD compared to dizygotic twins if on of the pair had the disorder
What did Cromer find about environmental risk factors in the role of OCD
-In one sample of his study, over half of people with OCD had experienced a traumatic event and OCD was more severe in those who had more than one trauma
What did Albucher find regarding the success of behavioural methods of treating OCD
-Symptoms of patients improved for 60-90% of adults when behavioural treatments of OCD were used
What is the behavioural explanation of OCD
The two Process Model:
The initial learning of the feared stimulus occurs through classical conditioning’s associative process, for example, dirt is paired with anxiety.
-This behaviour pattern would then be maintained through operant conditioning and negative reinforcement, whereby the stimulus is avoided and so the anxiety is removed.
-This could result in an obsession forming leading to the development of a compulsion, such as washing hands, which is performed to reduce the anxiety felt
Why may a diatheis stress model be a better explanation Of OCD
-Concordance rates in twin studies are never 100%
Why is it difficult to establish a cause and effect relationship with neural explanations
-While there is evidence to suggest that certain neural systems do not function normally in patients suffering from OCD, such as the basal ganglia or orbitofrontal cortex, research has also linked OCD to other areas of the brain.
-This means that there is no brain system which has consistently been found to play a role in OCD. Therefore, it cannot be concluded that there is a cause and effect relationship
Evaluation of genetic explanations
Strength: Support from family studies
Limitation: Role of environmental risk factors
Evaluation of neural explanations of OCD
Limitations
-Difficult to establish a cause and effect relationship
-Alternative explanations, e.g Two process model
What is the aim of drug therapy
-To restore neurochemical imbalances in the brain (the main cause of disorder)
What type of antidepressant drug is used to treat OCD
Selective serotonin reuptake inhibitors
(SSRIs)
What is the aim of SSRIs
To increase serotonin levels in the brain
How do antidepressants (SSRIs) work
-Antidepressants are designed to block the reuptake of serotonin, thereby increasing levels in the synapse
-This results in the post synaptic neuron being more likely to fire
-This therefore compensates for the lack of serotonin that would naturally be in the individuals system
-Thereby the symptoms of OCD are reduced
People with OCD with have :
-Less serotonin being released
OR
-Serotonin is being reabsorbed too quickly
Hereford, people with OCD often have low levels of serotonin
What is used if SSRI’s do not work
Anti anxiety drugs: Benzodiazepines
What is the aim of benzodiazepines
-To enhance the activity of the neurotransmitter GABA, which when released, has an inhibitory effect on many neurons in the brain, causing anxiety relief
How do benzodiazepines (anti anxiety drugs) work
-Benzodiazepines bind to GABA-A receptors on neurons
-This binding opens a channel that allows chloride ions to pass into the neuron
-The chloride ions make the neuron less responsive to other neurotransmitters
-This reduces neuronal excitability and produces a calming effect, relieving anxiety
Evaluation of biological treatments of OCD
-Evidence for its effectiveness
-Cost effective and non disruptive
-Side effects
-Treat the symptoms not the root cause
