Another biological explanation is brain biochemistry. Biochemical abnormalities may be important in the development and maintenance of schizophrenia. For example, schizophrenia may be a result from excess levels of the neurotransmitter dopamine. Neurons in the brains of a schizophrenic could be oversensitive to dopamine.
There is various evidence that dopamine plays a role in schizophrenia. Neuroleptic drugs that block dopamine seem to reduce the symptoms of schizophrenia. The phenothiazines are neuroleptic drugs that block dopamine at the receptors. They typically reduce many of the symptoms of schizophrenia.
Also drugs that increase dopamine activity, produce schizophrenic like symptoms in non schizophrenic people, (Davidson et al 1987). Similarly the symptoms of schizophrenic patients often become worse when they are given amphetamine which activates dopamine.
Post-mortems show a marked increase in the dopamine receptor sites in comparison to others. This suggests a super sensitivity to dopamine.
However there are some problems with the dopamine hypothesis. Neuroleptic drugs block dopamine fairy rapidly, but generally fail to reduce the symptoms of schizophrenia for days or weeks thereafter. Also there is a fairly new drug, Clozapine. It is frequently more effective than dopamine in reducing schizophrenic symptoms. It should be less effective according the dopamine hypothesis. Another negative point on the dopamine hypothesis is that antipsychotic medication does not work on a number of people, even if dopamine is reduced. It has been thought that someone could be wrongly diagnosed with schizophrenia but has a different mental disorder and don’t have high dopamine.
In conclusion the evidence on the relationship between schizophrenia and dopamine levels is mostly correlational. As a result it is not known whether the changed dopamine activity occurs before or after the onset of the disorder. If it occurs after then clearly dopamine plays no part in causing schizophrenic symptoms.
Another view of the cause of schizophrenia is the psychological explanation. They attempt to explain the process that underlies each of the different types of experience reported by people assigned the diagnosis.
The psychodynamic theory proposes (Freud) that conflicts and traumas are also of importance in schizophrenia. Schizophrenics regress or return to an earlier stage of psychosexual development (according to Freud). They have regressed to a state of primary narcissism which occurs early in the oral stage. The ego or rational part of the mind has not been separated from the id or sexual instinct. The lack of the ego development results in egotism and a loss of contact with reality, which is a huge symptom of schizophrenia. Freud argued that schizophrenics were driven by strong sexual impulses, which explains why schizophrenia often develops in late adolescence.
This approach to schizophrenia is limited in several ways. First, it is speculative, there is no evidence! Second, Freuds’ work is very dated which lacks temporal validity. Third, he used his own patients which could mean investigator bias and population bias. However there is some face validity. It does seem to make sense.
Another psychodynamic explanation of schizophrenia would be from the behavioural approach. According to the behavioural approach learning plays a key role in causing schizophrenia. The theory is that early experience of punishment may lead children to retreat into a rewarding inner world. This causes others to label them as “odd”. Their bizarre behaviour may be rewarded with attention and sympathy. This positive reinforcement encourages them to conform to the label. The behaviour becomes more exaggerated and eventually is labelled as schizophrenia.
The behavioural approach has some face validity, as it makes sense. However it lacks conviction of a causal explanation, and is more relevant to maintenance not a cause. The genetic/cognitive explanations may better account for the severity.
The diathesis stress model proposes that a complete explanation of any mental disorder is likely to involve both a predisposition to the disorder and a stressor which triggers the appearance of the symptoms. This can be seen to apply to schizophrenia where there is clear evidence of a genetic link, yet not everyone who inherits the genetic component becomes schizophrenic. We can explain this in terms of the psychological factors that trigger the disorder such as learnt behaviour or troubled family.
The importance of understanding the causes of schizophrenia lies in the decision of what form of treatment is desirable. Biological explanations lead to biological methods and behavioural explanations to behavioural methods. The most successful therapy has been the use of chemotherapy, a biological approach. This does not offer a cure but offers relief to sufferers.
