L12 Biological Explanations Of Obsessive Compulisve Disorder

Question 1

What doe the biological approach to explaining OCD assume ?

Answer 1

That OCD is caused by genetic and biochemical factors

Question 2

Background on the genetic explanation

Answer 2

OCD has been classed as polygenic; this means that one single gene is not
responsible for the disorder. Instead, as many as 230 genes might be
responsible for causing OCD; and they are known as candidate genes.

Question 3

What role does the COMT gene have ?

Answer 3

• may have a role in causing OCD
• COMT gene regulates the production of neurotransmitter dopamine, which in high level is associated with OCD
• one variation has been found to be more common in OCD patients than in people who don’t have OCD

Question 4

What role does the SERT gene have in OCD

Answer 4

• affects the transport of serotonin causing lower levels of serotonin
• low levels of serotonin have been linked to OCD
• individuals have the SERT gene on chromosome 17, it seems a mutation in this gene can cause OCD
• research conducted by Ozaki found 6/7 family members who had OCD had a mutation of the SERT gene

Question 5

Evaluation of genetic explanations ( 5x more likely)

Answer 5

Nestadt (2000) supports the genetic explanation for OCD. He found that people who had a first degree
relative who already had OCD were five times more likely to also get the illness. This supports the idea that OCD is
transmitted genetically

Question 6

Evaluation of genetic explanation (meta analysis)

Answer 6

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 (+)

Question 7

Evaluation of genetic explanations (concordance rate is not 100%)

Answer 7

A criticism of the genetics explanation is that the concordance rate for OCD is not 100%. Therefore OCD
cannot be caused entirely by genetic factors. The genetics explanation fails to take into account psychological and
environmental factors that might contribute to the cause of OCD

Question 8

Evaluation of genetic explanations (not a single gene is responsible)

Answer 8

A criticism for the genetics explanation for OCD is that it is polygenic and one single gene is not responsible for causing the disorder. OCD has been genetically linked to other illnesses such as Tourettes syndrome, and autism. Therefore it seems that the genetic cause for OCD is very complex and might be related to other illness too. It could be that one specific gene is not responsible for OCD, but could be a predisposing factor

Question 9

Evaluation of genetic explanations (contradict the behavioural approach)

Answer 9

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 (operant conditioning). The behavioural approach has gained a great deal of support in explaining the cause of OCD, especially as OCD is often treated using behavioural therapies s

Question 10

What two neurotransmitters affect OCD ?

Answer 10

• seretonin
• dopamine

Question 11

What do different levels of dopamine and serotonin change and in what way ?

Answer 11

They affect mood. Abnormal
levels of these neurotransmitters are associated with abnormal transmission of
mood-related information.

Question 12

What role does dopamine play in OCD?

Answer 12

· Dopamine is a neurotransmitters that affects mood and might be a cause of OCD

· The frontal lobes in the brain have been linked to dopamine activity.

· OCD sufferers 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.

· High dopamine levels have also been linked to over activity in the basal ganglia area in the brain (motor function and learning).

Question 13

What role does serotonin play in OCD ?

Answer 13

Serotonin is a neurotransmitters that affects mood and might be a cause of OCD

· The frontal lobes in the brain have been linked to serotonin activity.

· OCD sufferers tend to have low levels of serotonin and this can cause depressive like symptoms and also obsessive thoughts

· Many OCD sufferers are depressed due to the low levels of serotonin

· Serotonin plays a key role in operating the caudate nucleus in the brain, and it seems that low levels of serotonin cause the caudate nucleus to malfunction.

Question 14

What is the caudate nucleus ?

Answer 14

It works as a feedback processor, which means it uses information from past experiences to influence future actions and decisions. OCD patients have a malfunctioning caudate nucleus

Question 15

Evaluation of neural explanations (research support)

Answer 15

There has been a great deal of research support to state that neurotransmitters do cause OCD. Anti-depressant drugs will increase serotonin levels in OCD patients, and this has led to a reduction of OCD symptoms. Therefore there is good evidence to suggest that low levels of serotonin could be a cause for OC

Question 16

Evaluation of neural explanations (cause and effect)

Answer 16

A disadvantage of the neural explanation is that neurotransmitters such as dopamine and serotonin might not necessarily cause OCD. Instead low levels of serotonin and high levels of dopamine might be the effect of OCD. Therefore we must be cautious when looking at cause and effect of neurotransmitters

Question 17

Evaluation of neural explanations (OCD is comorbid with depression)

Answer 17

A problem with the neural explanation is that OCD is co morbid with depression (exists alongside depression). Therefore it is not clear whether low levels of serotonin cause OCD or depression or both? Therefore the link between low levels of serotonin causing OCD is not very clear and needs to be investigated further

Question 18

Evaluation of neural explanation (drug risperidone)

Answer 18

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

Question 19

Evaluation of neural explanation (unsure role of dopamine in cause)

Answer 19

The role of dopamine causing OCD has been questioned. It has been found that high levels of dopamine can also 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