Lesson 12 - OCD: Biological Approach To Explaining OCD (Genetic & Neural Explanations)

Question 1

Ao1: genetic cause of OCD

Answer 1

• Genes comes in different form (alleles) and it seems that genes could be the main cause of OCD.
• OCD might be inherited whereby sufferers have a genetic vulnerability or a genetic predisposition to get the illness
• Psychologists often use family or twin studies to investigate genetics
• OCD has been classed as polygenic; this means that one single gene is not responsible for the disorder.
• Instead, many genes might be responsible for causing OCD; and they are known as, candidate genes

Question 2

Ao1: COMT gene (genetic causes of OCD)

Answer 2

• COMT gene causes OCD
• 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
• COMT gene has been found to be more common in OCD patients than people who do not have the illness

Question 3

Ao1: SERT gene (genetic causes of OCD)

Answer 3

• This gene affects the transportation of serotonin which results in low levels of serotonin (resulting in low mood and depressive symptoms
• Individuals have the SERT gene on chromosome 17; seems a mutation in this gene can cause OCD
• Research conducted by Ozaki (2003) found evidence that 6 out of 7 family members who had OCD had a mutation of the SERT gene
• gene mutates which then causes low levels of serotonin to be produced
• seems that there is a link with OCD and depression and this might account for it
• it seems that OCD does have a genetic basis

Question 4

Ao3: strength of genetic explanations
(Nestadt supports genetic explanation for OCD)

Answer 4

• found that people who had a first degree relative who already had OCD were five times more likely to also get the illness
• supports the idea that OCD is transmitted genetically

Question 5

Ao3: strength of genetic explanations
(Billett supports idea OCD transmitted genetically)

Answer 5

• 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
• thus, this supports the idea that OCD is transmitted by genetics

Question 6

Ao3: weakness of genetic explanations
(Concordance rate not 100%)

Answer 6

• thus, OCD cannot be caused entirely by genetic factors
• genetics explanation fails to take into account psychological and environmental factors that might contribute to the cause of OCD

Question 7

Ao3: weakness of genetic explanations
(Behavioural approach would contradict genetic explanation for OCD)

Answer 7

• two process model would suggest that OCD can be learnt via classical conditioning, and then rewarded through reinforcement (operant conditioning)
• behavioural approach has gained a great deal of support in explaining the cause of OCD, especially as OCD is often treated using behavioural therapies such as exposure (similar to systematic desensitisation)

Question 8

Ao3: weakness of genetic explanations
(Polygenic - one single gene not responsible for causing disorder)

Answer 8

• OCD has been genetically linked to other illnesses such as Tourettes syndrome, and autism
• thus, it seems that the genetic cause for OCD is very complex and might be related to other illness too
• could be that one specific gene is not responsible for OCD, but could be a predisposing factor

Question 9

Ao3: weakness of genetic explanations
(Diathesis stress model disagrees with only the biological approach being the cause of OCD)

Answer 9

• can be caused by a combination of genes and a trigger in the environment (stress)
• thus, 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
• diathesis stress model would weaken the genetics argument

Question 10

Research by Beekman & Cath into genetics & OCD

Answer 10

• meta-analysis was conducted of twin studies into OCD that had occurred over the last 70 years.
  • MZ twins were compared against DZ twins
  • psychologists examined studies between 1929-1965 where OCD patients had been diagnosed using older criteria (before the DSM and ICD)
  • psychologists also examined studies after 1965, whereby OCD patients had been diagnosed using DSM criteria
  • 10,034 twin pairs were studied overall (from 28 separate twin studies)
  • The results found that in children, OCD is inherited via genes and the genetic influence ranges from 45-65%
  • The results found that in adults, OCD is inherited via genes and the genetic influence ranges from 27-47%
  • The conclusion was that OCD is transmitted genetically and this was more apparent when examining children rather than adults.

Question 11

Ao3: strengths & weaknesses of research by Beekman & Cath

Answer 11

1) - research can be criticised because the majority of the twin studies were not performed in controlled conditions
- means that the data is not very objective or scientific and therefore this might affect the validity and the reliability of the results gained from this research
- might question the idea that OCD is genetic (-)

2) research can be criticised because gene mapping was not taken into consideration when looking at whether OCD is genetic
- Gene mapping would look closely at the DNA of the twins that had OCD and compare this with twins that do not have OCD
- comparison need to be made in order to make the results more valid and robust

3) - strength of the research is that a large sample size was used
- this allows the results to be representative of the target population and they can be generalised

Question 12

Ao1: dopamine (neural explanation of OCD)

Answer 12

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

Ao1: serotonin (neural explanation of 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
• caudate nucleus plays a vital role in how the brain learns, specifically the storing and processing of memories : 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 14

Ao3: strength of neural explanations
(Research support stating neurotransmitters do cause OCD)

Answer 14

• Anti-depressant drugs will increase serotonin levels in OCD patients, and this has led to a reduction of OCD symptoms
• thus, there is good evidence to suggest that low levels of serotonin could be a cause for OCD

Question 15

Ao3: strength of neural explanations
(Research by Ciccerone support neural explanations of OCD)

Answer 15

• 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
• thus, it seems that high levels of dopamine could be a biological cause for OCD

Question 16

Ao3: strength of neural explanations
(Menzies suggested research evidence that would support a genetic link to abnormal levels of neurotransmitters)

Answer 16

• Menzies studied MRI scans (magnetic resonance imaging) in OCD patients and their immediate family members and compared them with healthy controls
• found that OCD patients and their families had reduced grey matter in key regions of the brain and they had an unusual neuroanatomy
• concluded that OCD can be caused by abnormal brain structure which could be inherited via genes

Question 17

Ao3: weakness of neural explanations
(Neurotransmitters might not necessarily cause OCD)

Answer 17

• Instead low levels of serotonin and high levels of dopamine might be the effect of OCD
• thus, we must be cautious when looking at cause and effect of neurotransmitters

Question 18

Ao3: weakness of neural explanations
(OCD is co morbid with depression)

Answer 18

• it is not clear whether low levels of serotonin cause OCD or depression or both?
• link between low levels of serotonin causing OCD is not very clear and needs to be investigated further

Question 19

Ao3: weakness of neural explanations
(Role of dopamine causing OCD has been questioned)

Answer 19

• has been found that high levels of dopamine can also cause other psychological illnesses and not just OCD
• high dopamine can cause bipolar depression and schizophrenia
• thus, there is not enough research evidence to suggest the high levels of dopamine can cause OCD to occur
• combination of factors might be responsible for causing the illness

Question 20

Ao1: neuroanatomy by Jenike & Rauch (neural explanations of OCD)

Answer 20

• might be a relationship between OCD being caused by some types of brain damage which might be caused by a virus (brain tumours or encephalitis when the brain swells due to a bacterial infection)
• brain damage might then cause a problem in the short term memory that causes a chain reaction of the person doubting whether they have performed a certain action recently
• a common characteristic of OCD and might then result in repetitive behaviour (compulsions) of repeatedly locking checking that the front door is locked
• OCD patients were studied using PET scans (position emission tomography)
• were shown an image of something dirty (they had a cleaning obsession)
• Evidence found that the frontal lobes and basal ganglia were the most active parts of the brain (compared to non OCD sufferers). It seems the basal ganglia might be overactive
• basal ganglia seems to malfunction in OCD sufferers
• basal ganglia refers to a series of interconnected brain structures that are at the front of the brain (near the orbital frontal cortex, which also seems to be overactive in OCD patients)
• basal ganglia is responsible for control of voluntary motor movements, procedural learning, habit learning, eye movements, cognition, and emotion
• overactive basal ganglia can lead to repetitive motor functions
• Patients who have Tourette’s syndrome also have problems with the basal ganglia, and it seems that many patients who have Tourette’s also have OCD and their symptoms are co-morbid (exist alongside each other).
• Further research has found that OCD sufferers might have damage to the frontal cortex of the brain
• This part of the brain is involved in selecting, controlling and inhibiting behaviour which OCD patients struggle with.