Making A level psychology easier

The biological model of abnormality

Also known as the medical model

Abnormal behaviour is caused by biological processes

Disorders of the brain and nervous system cause psychological disorders

Abnormality can be inherited

Main assumptions of the biological approach to abnormality
Psychological disorders are illnesses or diseases affecting the nervous system
Understanding abnormal behaviour as a physical illness removes all psychological blame and responsibility for the behaviour from the patient. It isn't their fault and they cannot help the way they behave.

Abnormal thinking, behaviour or emotions are caused by biological dysfunctions
Biological dysfunctions, such as changes in neurotransmitter levels, increased levels of certain hormones, or the dysfunction of certain neurones in the brain, can cause abnormal thinking, behaviour and emotions.

Understanding mental illness involves understanding what has gone wrong with the brain
Mental illness can be understood and therefore treated by understanding how the brain functions normally, and how abnormal brain function can cause abnormal behaviour. Treatments include drugs that correct abnormal biological functioning and surgery that fixes or removes dysfunctional components of the brain.

Possible causes of abnormal behaviour
Abnormal functioning of the brain can be caused by abnormal levels of neurotransmitters and hormones.

Neurotransmitters are the chemical messengers that allow neurones to communicate with one another at synapses (the gap between the end terminal of one neurone and the membrane of the dendrites or cell body of the next). Neurotransmitters that have been implicated in abnormal functioning include:
  • Serotinin. Low levels of serotonin are linked to depression, anxiety and obsessive compulsive disorder.
  • Dopamine. Parkinson's disease is caused by the death of dopamine producing cells in the substantia nigra. Addiction is linked to the reward pathways that use dopamine as a neurotransmitter.
Hormones are chemical messengers that are secreted into the bloodstream by glands and control various body functions including some nervous system functions. Hormones implicated in abnormal functioning include:
  • Cortisol. Chronic stress involves high levels of cortisol being produced by the adrenal cortex.
  • Insulin. Diabetes mellitus is caused by the inability of cells in the pancreas to produce insulin.

Structural damage or abnormality
Damage to certain areas of the brain, for example as the result of a head injury, stroke or brain surgery, or a failure of brain areas to develop properly can lead to abnormal behaviour:
  • Damage to the hippocampus, as seen in the cases of HM and Clive Wearing, can lead to profound memory loss.
  • Damage to Broca's area of the left temporal lobe may lead to the inability to understand speech properly.
  • Patients with schizophrenia have abnormally large ventricles in their brains.

Factors that may affect nervous system functioning
Genes are inherited from parents. Many psychological disorders occur more frequently in identical (monozygotic or MZ) twins than they do in non-identical (dizygotic or DZ) twins, and other disorders appear to run in families. Disorders that may be inherited include schizophrenia, autism, addiction and depression. Of course, the environment may also lead to these disorders and so it is important to estimate the degree to which a disorder is due to genetic influences (nature) and the degree to which it is caused by the environment (nurture). Comparing identical twins with non-identical twins for rates of heritability can help answer the nature-nurture question.

Infections, such as meningitis or herpes simplex encephalomyelitis, can lead to abnormal brain functioning.

Environmental poisons or toxins may lead to abnormal behaviour. One cause of transgenderism in males may be high levels of prenatal exposure to dioxins in pesticides. Mercury poisoning can cause abnormal behaviour such as the 'madness' that used to be seen in felt makers (immortalised in Lewis Carol's Allice in Wonderland's Mad Hatter).

Evaluating the biological model of abnormality
Research evidence
Plenty of studies have found that psychological disturbance is associated with biological changes (e.g. of neurotransmitters & hormones), however it is often impossible to tell whether such changes are a cause or an effect of the psychological symptoms. For example, patients with schizophrenia have enlarged ventricles in the brain, but it is not possible to say whether the ventricular enlargement is a causative factor in schizophrenia, or if it is a product of the disease.

The use of drugs to treat abnormal behaviour
The biological model has led to the development of drug therapies that are often effective in controlling psychological symptoms, for example antidepressant drugs effectively treat depression and antipsychotic drugs can control schizophrenia. However when drugs are discontinued, symptoms often return, suggesting the actual cause of the abnormality may not be purely biological. Drugs are good at quickly treating the symptoms of a disorder, but they are less effective at treating the actual cause of the disorder.

The role of the patient
The biological model offers people a role and treatments they are familiar with, and are often happy to go along with, for example it is easy to trust a doctor and easy to take the medications prescribed. However it encourages them to become passive and dependent and to hand over control of their lives to the expert. Therefore, instead of taking responsibility for the disorder and attempting to tackle the psychological cause, patients simply trust the treatment they are prescribed and expect it to cure them. A positive effect of this however may be that there is less social stigma toward a psychological disorder that is viewed as biological in origin as people tend to accept the patient cannot help being that way.

Blame and stigma
Biological processes are assumed to be beyond a patient’s control, and so patients they are not blamed for their predicament or behaviour.

A Level exam tips
Answering exam questions (PSYA2 AQA A specification)
Outline and evaluate the biological model of abnormality (12 marks)
6 AO1 marks. Explain and elaborate on the main assumptions of the biological model of abnormality. Make sure you refer to genes, neurotransmitters, hormones, brain damage, toxicity and disease. Unless the question specifically refers to biological treatments, you must avoid discussing them in the answer as no credit will be given.
6AO2 marks. Write a commentary on the effectiveness of the biological model as an explanation for abnormality. Discuss research evidence, the role of the patient, the use of drugs, and blame and stigma.