The biological model assumes psychological disorders are physical illnesses:

The biological approach assumes that psychological illnesses have physical causes. In principle, they’re no different from physical illnesses like the flu, except they have major psychological symptoms.

There are several biological explanations for OCD:

1. Genetic factors

   Some researchers think that genetics plays a part in OCD. Studies have looked at OCD rates among people with a relative who has OCD, to see if having a relative with OCD significantly increases your chances of developing it

Evidence for:

1. Billet et al (1998) did a meta-analysis of twin studies that had been carried out over a long period of time. They found that for identical twins, if one twin had OCD then 68% of the time both twins had it, compared to 31% for non-identical twins

2. Pauls et al (2005) found that 10% of people with an immediate relative (i.e. parents, offspring or siblings) also suffered from the disorder. This is compared to around 2% of people in the general population

Evidence against:

1. No study has found a 100% concordance rate, so genetics can’t be the full story of OCD. Children may imitate the obsessive and compulsive behaviour of their relatives

2. Concordance rates don’t prove that OCD itself has other contributing factors

Biochemical factors:

PET scans have shown that levels of the neurotransmitter serotonin are lower in OCD sufferers

Evidence for:

1. Insel (1991) found that a class of drugs called SSRIs, which increase levels of serotonin, can reduce symptoms of OCD in 50 to 60% of cases.

2. Zohar et al (1996) also found that SSRIs alleviated symptoms in 60% of patients with OCD

Evidence against:

1. SSRIs appear to offer some relief to sufferers of OCD. However, as this is not true in 100% of cases, there must be more to understanding OCD

2. The link with serotonin is correlational, so it doesn’t show cause and effect. It may be that decreased serotonin levels are a symptom of OCD, rather than a cause of it

Neurological Factors:

Some research using PET scans has found that abnormality in the basal ganglia within the brain may be linked to OCD

Evidence for:

1. Max et al (1995) found increased rates of OCD in people after head injuries that caused brain damage to the basal ganglia

2. Other researchers have found increased activity in this area during OCD-related thoughts and behaviours

3. OCD is often found in people with other diseases which involve the basal ganglia, e.g. Parkinson’s and Huntington’s disease

Evidence against:

1. Aylward et al (1996) didn’t find a significant difference in basal ganglia impairment between OCD patients and controls

2. Basal ganglia damage hasn’t been found in 100% of people with OCD, so it can’t be the full story

The Biological explanation of OCD has strengths and weaknesses:

Strengths:

1. It has a scientific basis in biology- there’s evidence that low serotonin and damage to the basal ganglia correlate with a causal relationship

2. Twin studies have shown that genetics have at least some effect on the likelihood of developing OCD

3. It can be seen as ethical- people aren’t blamed for their disorders; they just have an illness

Weaknesses:

1. The explanation doesn’t take into account the effect of the environment, family, childhood experiences or social influences- psychologists taking other approaches consider these sorts of things important factors

2. Biological therapies raise ethical concerns. Drugs can produce addiction and may only suppress symptoms rather than cure the disorder

OCD can be treated using biological therapy:

1. The biological approach to treating OCD involves drug therapy

2. Drug treatments usually work by increasing levels of serotonin in the brain using selective serotonin reuptake inhibitors (SSRIs). These are a type of antidepressant drug that increases the availability of serotonin

3. SSRIs prevent the reuptake of serotonin in the synaptic cleft. This means there’s more serotonin available to the next neuron

Advantages:

• Several researchers have found SSRIs to be effective in treating OCD. Thoren et al (1980) found that the use of an SSRI was significantly better at reducing obsessional thoughts than a placebo

• Research has found that using other antidepressants that don’t affect serotonin levels is ineffective at reducing OCD symptoms

Disadvantages:

• Up to 50% of patients with OCD don’t experience any improvement in their symptoms when taking SSRIs. Out of those that do improve, up to 90% have a relapse when they stop taking them

• SSRIs have to be taken for several weeks before the patient experiences an improvement in their symptoms

• Side effects of using these types of drugs include nausea and headaches, and sometimes increased levels of anxiety. This can cause people to stop taking their medication