The Biological Approach to explaining OCD Flashcards
What are the three parts to the biological approach?
Genetic explanation and the Neural explanations ( neurochemistry and neuroanatomy)
Within the neural explanation what are the two topics?
Neurochemistry and Anatomy
What is the genetic explanation regarding the Biological approach to do with inheritance and how is it checked?
OCD is likely to be inherited via parents through genes and DNA. This can be checked by examining if a patient’s family also have OCD. If this is the case, we’d expect first degree relatives to have a high rate of OCD, (parents, brothers/ sisters, children )
What did Lewis (1936) find out that supports the inheritance explanation with the biological approach?
Found that 37% of his OCD patients had a parent with it, and 21% had a sibling with it.
What is it called when there is a chance of you obtaining OCD from your family?
Concordance rate (agreement rate with familial members)
What are the two genes that are suggested to play a role in OCD development?
SERT gene
COMT gene
How does the SERT gene play a role in OCD?
A faulty copy of this gene causes serotonin to be re-absorbed too quickly by the nervous system, meaning it cannot play its normal role in blocking impulsive messages in the brain.
How does the COMT gene play a role in OCD?
It has been shown that faulty copies of this increase the amount of dopamine in the Limbic system which increases the amount of anxiety a person has. The increase anxiety drives the obsessions a person with OCD has.
Define polygenetic
More than one gene contributing to a disorder
What did Taylor (2013) to do support the genetic explanations?
Analysed the findings of previous studies and found evidence for 230 different genes playing a role in the disorder with many of the genes affecting serotonin and dopamine.
What is the scientific name for identical twins?
Monozygotic
What is the scientific name for non-identical twins?
Dizygotic
What did Nestadt et al. (2005) find regarding OCD with twins?
Reviewed twin studies published on OCD and found that 68% of identical twins shared OCD and 31% of non identical twins shared it, suggesting that there is a strong genetic component.
What did Marini + Stebinicki (2012) look at and find out regarding OCD with family members?
They looked at how common it was for two members of the same family to have OCD and found that it does seem to run in families.
What did Cromer et al. (2007) extend with regarding OCD and what can this suggest?
They found that over half of the patients with OCD had experienced a severe trauma in the past, the more severe it was the worse the symptoms of OCD.
This suggests genes interact with the environment to trigger OCD and influence its severity.
What are the characteristics of Neural Explanations?
Genes associated with OCD help to control and modulate the activity of neurotransmitters.
These explanations include both neurotransmitters and neuroanatomy
They overlap in many ways as different parts of the brain have different concentrations of neurotransmitters
What is the neural explanation regarding serotonin?
This is a neurotransmitter that helps to regulate mood by preventing impulsive thoughts from spreading across the brain. Low levels of this have been found in the frontal cortex and have been linked to the inability to stop the obsessions. However, some people with OCD have normal SERT genes, meaning there are other causes of OCD.
What is the neural explanation regarding dopamine?
Increased levels of dopamine have been found in the thalamus, part of the limbic system, and has been linked to an increase in anxiety.
What is the neural explanation regarding changes in the way that the frontal lobe is functioning?
The frontal lobe forms part of the worry circuit, along with the limbic system. If the worry circuit is not controlled by the frontal cortex then anxious thoughts can spiral out of control.
What does the parahippocampus gyrus do and how does it function with some OCD patients?
It plays a role in processing unpleasant emotions and has been found to function abnormally in some OCD patients
What is the final neural explanation to do with multiple brain areas?
Multiple brain areas are involved with OCD and the genes interact with both the brain areas and the associated neurotransmitters.
What did Nedstadt et al. (2010) find regarding one of the best treatments for OCD being antidepressants?
They found that OCD symptoms are common in other illnesses where there has been damage to the neurotransmitter systems.
Define gyrus
These are the bumps on the brain
Define Salcus
These are the dips on the brain
Define cortex / lobe
This is the outer layer of the brain
What is the main issue with the serotonin explanation regarding OCD?
50% of people with OCD also have clinical depression, which is also linked to low levels of serotonin. Therefore, the low levels of serotonin seen in OCD might be due to the comorbid disorder of depression, not the OCD itself.
What did Pichichero (2009) find out regarding child cases of OCD? (2 things)
Found that a significant number of US child cases had suffered from an infection of strep throat shortly before developing symptoms of OCD.
Also found that they developed Tourette’s which is a separate disorder with issues in similar parts of the brain as OCD.
Suggests that damage to the nervous system by a virus can explain OCD
What did Fallon and Nields (1994) find out regarding people being infected with Lyme’s disease?
Found that 40% of people who were infected by Lyme’s diseases ( bacterial infection caused by ticks) went on to suffer from neural damage which resulted in OCD
What did Saxena + Rausch (2000) find evidence for and what is the advantage of using these?
Found consistent evidence for the role of the frontal cortex in OCD through PET, fMRI, MRI studies. Several different techniques being included presents stronger evidence and suggests that brain areas are involved with the disorder.
What does MRI stand for?
Magnetic resonance imaging
What fMRI stand for?
Functional magnetic resonance imaging
What is another main issue with the biological explanations to OCD regarding correlations?
Much of the research is based on correlations which cannot provide causal explanations. Links can only be made between biology and OCD, and there is no cause and effect.
Would be too unethical to run experiments due to chance of causing possible damage to ppt’s brain
What is the very simplified explanation of the interaction between dopamine and serotonin?
Too much dopamine drives anxiety in the limbic system which increases the anxiety felt in the worry circuit. The frontal cortex has lower than usual serotonin and this means that the impulsive thoughts and anxiety cannot be inhibited (controlled)
What is the alternative explanation, instead of the biological approach to OCD?
The cognitive approach which involves faulty thoughts that a person has
What did Rachman and Hodges (1987) find which supports the alternative explanation, cognitive approach, to OCD?
Found that OCD patients had increased cognitions related to their OCD + that these were based in the frontal cortex— suggests a link between biology and the obsessions an OCD patient has.
What is the diathesis - stress hypothesis regarding the biological approach to OCD?
People are born with a genetic / biological risk for OCD that environmental experiences, learning an cognitions play a role in the specific symptoms a patient suffers from/
What is the name for the cognitive and biological combined approach?
Cognitive neuroscience
Define diathesis
Genetic predisposition
Define stress in the ‘diathesis stress model’
The environmental stimuli that triggers something
