The Biological Approach to Explaining OCD

Question 1

What are the 2 biological explanations for OCD?

Answer 1

1. genetic explanation

2. neural explanation

Question 2

What are the 3 genetic explanations for OCD?

Answer 2

1. COMT gene
2. SERT gene
3. diathesis-stress

Question 3

How does the COMT gene explain OCD?

Answer 3

COMT regulates the production of the neurotransmitter dopamine that has been implicated in OCD. One form of the COMT gene has been found to be more common in OCD patients than people without the disorder. This variation produces lower activity of the COMT gene and higher levels of dopamine

Question 4

What is the main genetic explanation for OCD?

Answer 4

individuals inherit specific genes from their parents that are related to the onset of OCD

Question 5

How does the SERT gene explain OCD? (+study!!)

Answer 5

the SERT gene affects the transport of serotonin, creating lower levels of this neurotransmitter. These lower levels are also implicated in OCD. One study found a mutation of this gene in two unrelated families where six of the seven family members had OCD (Ozaki et al., 2003)

Question 6

What is the job of the COMT gene?

Answer 6

to regulate the production of the neurotransmitter dopamine

Question 7

What does the SERT gene affect?

Answer 7

the transport of serotonin (creating lower levels of it)

Question 8

How does the diathesis-stress explain OCD?

Answer 8

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.

Question 9

What are the 2 neural explanations for OCD?

Answer 9

1. abnormal levels of neurotransmitters

2. abnormal brain circuits

Question 10

What is the main neural explanation for OCD?

Answer 10

genetic factors affect certain brain circuits that may be abnormal. and therefore, lead to abnormal behaviour

Question 11

How do abnormal levels of neurotransmitters explain OCD? (+ x3 studies!! )

Answer 11

• dopamine levels are thought to be abnormally high in people with OCD. This is based on animal studies - high does of drugs that enhance levels of dopamine induce stereotyped movements resembling the compulsive behaviours found in OCD patients (Szechtman et al., 1998)
• low levels of serotonin are also associated with OCD. This conclusion is 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 12

How do abnormal brain circuits explain OCD? (+ x2 studies!! )

Answer 12

Several areas in the frontal lobes of the brain are thought to be abnormal in people with OCD. The caudate nucleus (located in the basal ganglia) normally suppresses signals from the orbitofrontal cortex (OFC). In turn, the OFC sends signal 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 sends signals back to the OFC, acting as a worry circuit

Serotonin and dopamine are linked to these regions of the frontal lobes. Comer (1998) reports that serotonin plays a key role in the operation of the OFC and the caudate nuclei, and it would therefore appear that abnormal levels of serotonin might cause these areas to malfunction. Dopamine is also linked to this system, as it is the main neurotransmitter of the basal ganglia. High levels of dopamine lead to overactivity of this region (Sukel, 2007)

Question 13

What study supports the idea that several areas in the frontal lobes of the brain are abnormal in people with OCD?

Answer 13

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 14

What are the 5 evaluation points for the biological approach to explaining OCD?

Answer 14

1. family and twin studies
2. tourette’s syndrome and other disorders
3. research support for genes and OFC
4. real world application
5. alternative explanations

Question 15

What is the PEEL paragraph for the biological explanation to explaining OCD evaluation point; family and twin studies

Answer 15

P - evidence for the genetic basis of OCD comes from studies of first-degree relatives (parents or siblings) and twin studies
E - Nestadt et al., (2000) identified 80 patients with OCD and 343 of their first-degree relatives and compared them with 73 control patients without mental illness and 300 of their relatives. They found that people with a first-degree relative with OCD had a five0times greater risk of having the illness themselves at some time in their lives, compared to the general population.
E - a meta analysis of 14 twin studies of OCD found that, on average, identical (monozygotic, MZ) twins were more than twice as likely to develop OCD if their co-twin had the disorder than was the case for non-identical (dizygotic, DZ) twins (Billet et al., 1998)
L - this evidence points to a clear genetic basis for OCD, but the fact that the concordance rates are never 100% means that environmental factors must play a role too 9the diathesis-stress model)

Question 16

What is the PEEL paragraph for the biological explanation to explaining OCD evaluation point; tourette’s syndrome and other disorders

Answer 16

P - evidence of the role of genes in OCD comes from studies of people with other disorders
E - Pail and Leckman (1986) studied patients with Tourette’s syndrome and their families, and concluded that OCD is one for of expression of the same gene that determines Tourette’s. The obsessional behaviour of OCD and Tourette’s patients is also found in children with autism, who display stereotyped behaviours and rituals as well as compulsions. In addition, obsessive behaviour is typical of anorexia nervosa, and is one of the characteristic distinguishing individuals with anorexia from patients with bulimia.
E - Furthermore, it is reported that 2/3 patients with OCD also experience at least one episode of depression (Rasmussen and Elsen, 1992)
L - this all supports the view that there is not one specific gene or genes unique to OCD, but they merely act as a predisposing factor towards obsessive-type of behaviour

Question 17

What is the PEEL paragraph for the biological explanation to explaining OCD evaluation point; research support for genes and OFC

Answer 17

P - many studies demonstrate the genetic link to abnormal levels of neurotransmitters
E - for example, Menzies et al., (2007) used MRI to produce images of brain activity in OCD patients and their immediate family members without OCD (a sibling, parent or child) and also a group of unrelated healthy people.
E - OCD patients ad their close relatives had reduced grey matter in key regions of the brain, including the OFC
L - this supports the view that anatomical differences are inherited and these may lead to OCD in certain individuals. Menzies et al., concluded that in the future brain scans may be used to detect OCD risk

Question 18

What is the PEEL paragraph for the biological explanation to explaining OCD evaluation point; real world application

Answer 18

P - the mapping of the human genome has led to the hope that specific genes could be linked to particular mental and physical disorders
E - for example, it might be that where one or the other parent-to-be has the COMT gene, the mother’s fertilised eggs could be screened, thus giving the parents the choice of whether to abort those eggs with the gene.
E - alternatively, gene therapy may produce a means of turning certain genes ‘off’ so that a disorder is not expressed. Both raise important ethical issues, not least that the same genes may have other benefits. Furthermore this presumes that there is a relatively simple relationship between a disorder, such as OCD, ad genes, which may well not be the case
L - applying biological therapies (such as gene therapy) is therefore more complex and controversial than it may first appear

Question 19

What is the PEEL paragraph for the biological explanation to explaining OCD evaluation point; alternative explanations

Answer 19

P - the biological approach faces strong competition from psychological explanations
E - the two-process model can be applied to OCD. Initial learning occurs when a neutral stimulus (such as dirt) is associated with anxiety. This association is maintained because the anxiety-provoking stimulus is avoided. Thus an obsession is formed a nd then a link is learned with compulsive behaviors (such as hand washing) that appear to reduce the anxiety
E - Such explanations are supported by the success of a treatment for OCD called exposure and response prevention (ERP) which is fairly similar to systematic desensitisation. Patients have to experience their feared stimulus and at the same time are prevented from performing their compulsive behaviour. Stude that reported high success rates, for example Albucher et al., (1998) report that between 60 and 90% of adults with OCD have improved considerably sing ERP
L - this suggests that OCD may have psychological causes as well as, or instead of, biological causes