PP- Biological approach to explaining OCD

Question 1

What are the genetic causes of OCD?

Answer 1

• candidate genes ,makes person vulnerable to OCD
• for example the 5HTT gene in transport of serotonin across synapses
• The COMT gene & the SERT gene

Question 2

What is the COMT gene?

Answer 2

• The COMT gene causes OCD.
• The COMT gene regulates the production of the neurotransmitter dopamine which in high levels is associated with OCD.
• High levels of dopamine are responsible for drive, motivation and possibly aggression.

Question 3

What is the SERT gene?

Answer 3

• Serotonin Transport gene
• This gene affects the transportation of serotonin which results in low levels of serotonin, resulting in low mood and depressive symptoms.
• has a role in preventing repetitive behaviours.

Question 4

strengths of the genetic explanation of OCD

Answer 4

1) Lewis (1936) - 37% of the patients had parents with the disorder and 21% had siblings.

Nestadt et al.(2000) take this point further and proposes that individuals who have a first‐degree relative with OCD are up to five times more likely to develop the disorder in their lifetime compared to members of the general population without this genetic link. Research from family studies like this provides support for a genetic explanation for OCD

CP: although it does not rule out other (environmental) factors playing a role. This explanation for OCD reduces a complex human behaviour to a single gene or brain chemical and so is considered biologically reductionist. For example, the biological explanation does not consider the role cognitions (thinking) or learning in the development or maintenance of OCD and is therefore criticised by behavioural and cognitive psychologists for its overly simplistic view.

2) Billett (1998) supports the idea that OCD is transmitted genetically. He found from a meta analysis of 14 twin studies that OCD is twice more likely to be concordant in identical monozygotic twins rather than dizygotic non identical twins. Therefore this supports the idea that OCD is transmitted by genetics.
cp: Since concordance rates in twin studies are never 100%, it suggests that the diathesis‐stress model may be a better explanation whereby a genetic vulnerability is inherited and triggered by a stressor in the environment. The diathesis stress model would argue that OCD can be caused by a combination of genes and a trigger in the environment. Therefore genes alone cannot be the only cause of OCD; genes would need to be combined with other factors in order for the disorder to develop.

Question 5

What are the neural explanations of OCD?

Answer 5

abnormal levels of neurotransmitters and abnormal brain circuits cause OCD

1) Abnormal levels of neurotransmitters:
It is thought that lower levels of serotonin are associated with OCD as it has a role in preventing repetitive behaviours. A lack of serotonin therefore results in the loss of the mechanism that inhibits task repetition. Evidence for this comes from research examining antidepressants (SSRIs). Piggott etal. (1990) found that drugs which increase the level of serotonin in the synaptic gap are effective in treating patients with OCD. Abnormal levels of serotonin might cause a malfunction of the OFC and the caudate nuclei

OCD sufferers also have high levels of dopamine. Research conducted on animals has found that high doses of drugs that enhance dopamine levels can induce movements that resemble compulsive and repetitive behaviour, which is similar to what OCD sufferers would experience.

2) Abnormal brain circuits:
When the basal ganglia is damaged, it fails to suppress the minor worry signals that the occipital frontal cortex sends the basal ganglia

Question 6

What are the strengths of neural explanations?

Answer 6

1) Research conducted by Ciccerone (2000) would support the neural explanations of OCD. He found that giving OCD patient’s low doses of the drug Risperidone helped to lower dopamine levels and alleviate some of the symptoms of OCD. Therefore it seems that high levels of dopamine could be a biological cause for OCD.

2) Paul et al. using neuroimaging has repeatedly
found unusually high activation within the OFC and several studies have found excessive activity in the caudate nucleus. Further, PET scans of patients with OCD, taken while their symptoms are active (e.g. when a person with a germ obsession holds a dirty cloth) show heightened activity in the OFC. This is a strength as it shows there is strong objective and
empirical evidence that suggests certain brain circuits are associated with OCD, increasing the validity of the neural explanation for OCD.

Question 7

What are the weaknesses of neural explanations?

Answer 7

1) CANNOT ESTABLISH A CAUSE AND EFFECT :
research from brain scan studies show an association
between increased activity in certain brain areas (e.g. the orbitofrontal cortex) and OCD. As it is only an association it doesn’t show that those brain areas play
a role in causing OCD. This is an issue as these biological abnormalities could be a consequence of OCD rather than its cause. Reduces validity of explanation.

3) co morbidity - The role of dopamine causing OCD has been questioned. It has been found that high levels of dopamine can cause other psychological illnesses and not just OCD. For instance high dopamine can cause bipolar depression and schizophrenia. Therefore there is not enough research evidence to suggest the high levels of dopamine can cause OCD to occur. A combination of factors might be responsible for causing the illness.

Question 8

what are the two biological explanations for OCD ?

Answer 8

neural and genetic

Question 9

how can OCD be explained genetically ?

Answer 9

OCD is inherited through genetic transmission. Researchers have found genes that lead to a vulnerability for OCD, known as OCD candidate genes
• An example of this is the 5- HTT genes, which has an effect on the transportation of serotonin. A mutation of this causes a lower level of serotonin in the
synapse. A study has found that a mutation in the 5-HTT gene in families, where 6 out of 7 people had OCD
• Polygenic disorder (multiple genes) – other researchers believe that OCD might be a polygenic disorder (not caused by one gene). Taylor conducted a
meta-analysis and found evidence of up to 230 different genes involved in OCD

A gene that has been linked to OCD is the COMT gene and SERT gene

Question 10

weakness of genetic explanation for OCD

Answer 10

1) The behavioural approach would contradict the genetic explanation for OCD. The two process model would suggest that OCD can be learnt via classical conditioning, and then rewarded through reinforcement. For example if dirt/germs are paired with anxiety (e.g. becoming ill). Compulsive behaviour (e.g. continual hand washing) is then maintained through operant conditioning and negative reinforcement, as the compulsive behaviour reduces the anxiety associated with the anxiety‐inducing stimulus which serves to reinforce the condition. Support for this is 60–90% of adults (Albucher etal., 1998) improved symptoms after behavioural treatments for OCD
3) environmental factors can affect OCD, cromer (2007) found over half old patients experienced traumatic event, shows genetic explanation only partially explains and is BIOLOGICALLY REDUCTIONIST

Question 11

biological approach

Answer 11

perspective that emphasises the significance of physical processes in the body such as genetic inheritance and neural function.

Question 12

what is abnormal in HOARDING disorder ?

Answer 12

• abnormal functioning of lateral frontal lobes = responsible for logical thinking and making decisions
• and parahippocampal gyrus = associated with unpleasant emotions