Explanations of Schizophrenia
Explanations of Schizophrenia
No single cause has been identified, biological, behavioural and social research suggests a complex interplay between factors. For example, people might have an inherited tendency towards schizophrenia that is triggered by environmental circumstances.
Family history studies show that schizophrenia tends to run in families.
The rate of schizophrenia in the general population is about 1%, but estimates vary.
Studies using twins show that in identical (monozygotic or MZ) twins, if one has schizophrenia, the other has 40-50% chance of developing the illness.
Concordance rates for schizophrenia are three times higher in identical twins than non-identical twins (dizygotic or DZ).
If one parent has schizophrenia then a child has about ten percent chance of developing it.
The problem with families, including twins, is that they share the same environment.
The search for genes that may contribute to schizophrenia has indicated that chromosomes number 6 and 13 might be involved, but evidence so far is uncertain.
Genetic factors could be behind biochemical or neurological defects outlined below.
The main biochemical explanation for schizophrenia is the dopamine hypothesis. This idea is based on the role of chemical messengers between nerve cells called neurotransmitters. There seems to be a chemical imbalance in the action of the neurotransmitter dopamine in the brains of those with schizophrenia.
Evidence for the dopamine hypothesis:.
Drugs: Antipsychotic or neuroleptic drugs are known to dampen the effects of dopamine, by blocking dopamine receptors. These help to relieve symptoms of hallucinations and delusions in many sufferers.
A good way to picture this is to imagine a house (the brain) with very noisy, partying, inhabitants (overactive dopamine system). Now imagine the windows and doors being firmly closed to muffle the noise - this is like the action of neuroleptic drugs.
More evidence for the dopamine hypothesis comes from drugs that increase the release of dopamine, for example, amphetamines. An overdose produces symptoms like those of schizophrenia. This is known as amphetamine psychosis.
Studies have shown enlargement of the cerebral ventricles (fluid-filled spaces of the brain) in some, but not all people with schizophrenia.
Post-mortem studies have shown changes in the amount and distribution of brain cells in some people with schizophrenia.
Researchers think these changes might occur before people are diagnosed with the disease - schizophrenia could be a disorder in the way the brain develops. Errors in brain development may remain dormant for years.
This theory is supported by the fact that schizophrenia is usually diagnosed in young adults before the age of 45, but not in children.
People diagnosed with schizophrenia come from all types of social backgrounds, but most are clustered in the lower socio-economic groups and live in the poorest areas of cities. This has led to suggestions that social factors might be important.
The sociogenic hypothesis suggests that poor social conditions create stresses that trigger schizophrenia in some people.
The social drift hypothesis suggests that people with schizophrenia are unable to function normally, lose their jobs and drift into lower social classes, and poor areas of cities.
Some psychologists suggest that dysfunctional family relationships with 'abnormal' communication may play a part, creating highly stressful environments. However, this might be due to difficulties in coping with a member of the family who is mentally disturbed, not the reason for the illness.
In the 60's, Laing suggested that schizophrenia might be a rational response to feeling trapped in a mad world. Once diagnosed and labelled the person is seen as 'ill'. Medical treatments, which may be unsuitable, are then imposed on individuals.
The problem with Laing's anti-psychiatry view is that more recent, strong evidence indicates that schizophrenia is a physical disease of the brain.