Outline and Evaluate One or More Biological Explanations to Schizophrenia

Outline and evaluate one or more biological explanations of schizophrenia (8 marks AO1/16 marks AO1) Schizophrenia is classified as a mental disorder that shows profound disruption of cognition and emotion which affects a person’s language, perception, thought and sense of self. The dopamine hypothesis states that schizophrenic’s neurones transmitting dopamine release the neurotransmitter too easily, leading to the characteristic symptoms of schizophrenia.

This hypothesis claims that schizophrenics have abnormally high amounts of D2 receptors; receptors that receive dopamine, therefore resulting in a higher amount of D2 receptors binding to the receptors causing more impulses. Dopamine neurotransmitters play a key role in guiding attention, so an imbalance of this neuron leads to problems relating to attention, perception and thought. Amphetamines are a dopamine agonist drug, which stimulates the neurons containing dopamine. According to the dopamine hypothesis, large doses of the drug lead to the characteristic schizophrenic symptoms, hallucinations and delusions.

The development and use of Antipsychotic drugs to treat schizophrenia support the dopamine hypothesis. The drugs work by blocking activity of dopamine and have been shown to alleviate symptoms of schizophrenia, such as hallucinations, delusions and thinking problems associated with the disorder. This is because by reducing dopamine activity helps to maintain a constant level in guiding attention, leading to a decrease in key schizophrenic symptoms of hallucinations and delusions because they can be caused by being overly attentive.

Statistics increase the reliability of the biological explanation of the dopamine hypothesis for explaining schizophrenia; as they show Antipsychotics have a 60% success rate. Therefore, this shows a link between high levels of dopamine activity and schizophrenia, as antipsychotics work by blocking the dopamine activity. This has led to more effective treatment, allowing those with schizophrenia to improve their quality of life, However, a meta-analysis investigation on post mortem studies on schizophrenics has produced contradicting evidence about the dopamine hypothesis.

The contradictive evidence by Haracz (1982) showed that those who died whilst on a course of the antipsychotic drugs actually had higher levels of dopamine activity than those not using the antipsychotic drugs. This occurs because the neurotransmitter builds up in the synapse of the neurone whilst the drug blocks to D2 receptors and as the drug wears off, more impulses are initiated by the neurotransmitters, causing the schizophrenic symptoms.

This means the dopamine hypothesis lack reliability in explaining schizophrenia because antipsychotics could be responsible for increasing dopamine activity and therefore actually increase the schizophrenic symptoms such as hallucinations and delusion, which decreases the schizophrenic’s quality of life as they live in a constant psychosis state where they have lost touch with reality. The development of neuroimaging techniques such as PET scans (a 3D image of the brain obtained by a nuclear machine) has led to supporting evidence for numerous explanations, yet has so far failed to provide evidence supporting the dopamine hypothesis.

This questions the reliability of the biological approaches claim that increased activity of the neurotransmitter dopamine as the neurologists have closely examined the brain and differences in dopamine activity in schizophrenics and healthy individuals. This lack of evidence means that treatments produced to help those with schizophrenia may not be successful in treating schizophrenia as there may be a possibility that the dopamine hypothesis is not accurate in explaining schizophrenia. The biological explanation of schizophrenia also claims that the disorder can be inherited.

The more common the disorder is among the biological relatives and the closer the degree of genetic relatedness increases the risk of the child developing schizophrenia. Gottesman’s research (1991) found a genetic link with schizophrenia when looking at children and their relatives. The research discovered that children with two schizophrenic parents have a concordance rate of 46% compared to children who just have one schizophrenic parent to children who have a concordance rate of 13% and siblings just 9%.

The genetic theory of schizophrenia also suggests that monozygotic twins (twins who a genetically identical) should have a higher concordance rate of schizophrenia than dizygotic twins (twins who are not genetically identical) because they have a closer degree of genetic relatedness. Adoption studies support the genetic theory that schizophrenia can be inherited as they provide evidence that the environment does not affect inheritance rate. The supporting study was carried out by Tienari in Finland. He investigated 164 adoptees that biological mothers have been diagnosed with schizophrenia and found 6. % also received a diagnosis, compared to 2% of the control group of adoptees. This means that that there is a genetic liability to schizophrenia, as more of with the biological mother having schizophrenia develop schizophrenia than the control group. As a result, this increases reliability of the biological approaches explanation to schizophrenia as it indicates genetic factors play a major role in the development of schizophrenia and environmental factors such as a different upbringing do not inhibit this.

However, Tienari’s research did not produce a statistic proving the majority of those who have biological mothers with schizophrenia developed the disorder later in life. The study showed only 6. 7% of the adopted children with a relative with schizophrenia developed the disorder, yet 93. 3% didn’t develop the disorder. This suggests that environmental factors also play a key role in causing schizophrenia – not just the genetic factors – which inclines a lack of internal validity to the biological explanation.

This means that the therapies based on the biological explanation of schizophrenia will not be effective as they do not consider all factors affecting the disorder, leading to those suffering with schizophrenia not able to improve their quality of life. Investigations on monozygotic and dizygotic twins also support the theory that genetic factors play an important role in schizophrenia. The study showed that there was a concordance rate of 40. 4% for monozygotic twins yet only 7. 4% concordance rate of dizygotic twins.

A concordance rate shows how many times both twins developed the disorder. These findings supports the genetic position because they show the monozygotic concordance rate, twin who are 100% genetic similar, to be far higher than dizygotic twins, who only have about a 50% genetic similarity. Therefore, this increases the reliability of the biological explanation of schizophrenia as it shows that the closer degree of genetic similarity there is, the increased likelihood of the relative developing the disorder. It can be argued that the biological explanation to schizophrenia is reductionist.

This is because it does not consider the environmental factors involves with developing schizophrenia, only what does on inside the brain. For example, the genetic theory states that schizophrenia is inherited, yet research only found a concordance rate of 40. 4% for monozygotic twins. If schizophrenia was caused 100% by inheritance and degree of genetic similarity, the concordance rate for monozygotic twins should be 100% as they are genetically identical. Thereby, this reduces the reliability of the biological explanation as it does not consider other factors affecting schizophrenia, such as the environmental factors.