P - The biological approach to explaining OCD

Question 1

What approach do we study for explaining OCD?

Answer 1

The biological approach

Question 2

What does the genetic explanation of explaining OCD say is the cause of OCD?

Answer 2

Specific genes being inherited from parents related to the onset of OCD.

Question 3

What genes do we need to know about in the biological approach to explaining OCD?

Answer 3

COMT and SERT genes.

Question 4

What does the COMT gene do?

Answer 4

Regulates the production of the neurotransmitter dopamine and is involved in the production of catechol-O-methyltransferase.

Question 5

What does COMT stand for?

Answer 5

Catechol -O-methyltransferase.

Question 6

What do genes come in?

Answer 6

Different forms (alleles).

Question 7

Where has one form/allele of the COMT gene found to be more common?

Answer 7

In OCD patients compared to people without the disorder.

Question 8

The COMT gene is more common in OCD sufferers - what does this do to the COMT genes activity and the levels of dopamine?

Answer 8

Lowers the activity levels of the COMT gene but means there is a higher level of dopamine (Tukel et al., 2013).

Question 9

What is the SERT gene also known as?

Answer 9

5-HTT

Question 10

What does the SERT gene do?

Answer 10

Affects the transport of the serotonin, creating lower levels of this neurotransmitter.

Question 11

What is the study done on the SERT gene?

Answer 11

Study found a mutation of this gene in 2 unrelated families where 6 out of the 7 family members had OCD (Ozaki et al., 2003).

Question 12

What does diathesis-stress model suggest in OCD and other disorders?

Answer 12

That each individual gene only creates a vulnerability (a diathesis) for OCD as well as other conditions, such as depression. Other factors (‘stressors’) affect what condition develops or indeed whether any mental illness develops.

Therefore some people could possess the COMT or SERT gene variations but suffer no ill effects.

Question 13

What is concordance rate?

Answer 13

A measure of genetic similarity.

In a sample of, for example, 100 twin pairs, one twin of each pair has a phobic disorder. The number of times their other twin also shows the illness determines the concordance rate,so if 40 have phobic disorder, then the concordance rate is 40%.

Question 14

What is dopamine?

Answer 14

One of the key neurotransmitters in the brain, with effects on motivation and ‘drive’.

Question 15

What is a gene?

Answer 15

A part of the chromosome of an organism that carries information in the form of DNA.

Question 16

What are neurotransmitters?

Answer 16

Chemical substances that play an important part in the workings of the nervous system by transmitting nerve impulses across a synapse.

Question 17

What does the neural explanation of OCD suggest causes the issue?

Answer 17

Abnormal levels of neurotransmitters.

Abnormal brain circuits.

Question 18

What are dopamine levels like in people with OCD?

Answer 18

High

Question 19

What evidence is there for dopamine levels being high in people with OCD?

Answer 19

Animal studies - high doses of drugs that enhance levels of dopamine induce stereotyped movements resembling the compulsive behaviours found in OCD patients (Szechtman et al., 1998).

Question 20

What are serotonin levels like in people with OCD?

Answer 20

Low

Question 21

What evidence is there for serotonin levels being low in people with OCD?

Answer 21

Based on the fact that antidepressant drugs that increase serotonin activity have been shown to reduce OCD symptoms (Pigott et al., 1990), whereas antidepressants that have less effect on serotonin do not reduce OCD symptoms (Jenicke, 1992).

Question 22

What area of the brain is said to be abnormal in those with OCD?

Answer 22

Several areas in the frontal lobes of the brain.

Question 23

What happens in an OCD brain when there are worrying thoughts?

Answer 23

The caudate nucleus in the basal ganglia normally suppresses signals from the orbitofrontal cortex (OFC). In turn, the OFC sends signals to the thalamus about things that are worrying, such as a potential germ hazard. When the caudate nucleus is damaged, it fails to suppress minor ‘worry’ signals and the thalamus is alerted, which in turn send signals back to the OFC, acting as a worry circuit.

Question 24

When is a worry circuit created?

Answer 24

The OFC sends ‘worry’ signals to the thalamus. These are normally suppressed by the caudate nucleus but, if damaged, then the thalamus is alerted and confirms the ‘worry’ to the OFC, creating a worry circuit.

Question 25

The idea that abnormal brain circuits may be an explanation to OCD is supported by what evidence?

Answer 25

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). Such scans show heightened activity in the OFC.

Question 26

What neurotransmitters are said to be linked to regions in the frontal lobe according to the explanations of OCD?

Answer 26

Dopamine and serotonin.

Question 27

What did Comer (1998) say the role serotonin plays in the frontal lobe?

Answer 27

Plays a role in the operation of the OFC and the caudate nuclei - and so it would appear that abnormal levels of serotonin might cause these areas to malfunction.

Question 28

What might abnormal levels of serotonin in regions of the frontal lobe cause to happen?

Answer 28

Might cause these areas to malfunction.

Question 29

What is the main neurotransmitter of the basal ganglia?

Answer 29

Dopamine.

Question 30

What do high levels of dopamine lead to in the brain?

Answer 30

Overactivity of the basal ganglia region of the brain (Sukel, 2007).