Biological Explanations Schizophrenia Essay

Compare and contrast psychological and biological explanations of EITHER major depression OR schizophrenia





This essay compares and contrasts psychological and biological explanations of schizophrenia. This will be done via a point by point comparison of both psychological and biological explanations of schizophrenia at the same time, while first pointing out similarities in their explanation of psychotic symptoms and thereafter any differences. 

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What is schizophrenia?

Schizophrenia refers to a mental disorder characterized by a breakdown in cognitive functioning and processes responsible for normal thought, emotions and ways of behaving. The result of this psychotic breakdown is faulty perception, hallucinations, inappropriate behaviour and delusions. Grand delusion is perhaps one of the more common or reported symptoms of schizophrenics with delusions of persecution or grandeur. According to Maher (2001), at least 75% of schizophrenics experience symptomatic delusions of some sort. 


Comparisons between psychological and biological explanations of schizophrenia

Schizophrenia can be explained by many theories including psychological and biological explanations each explaining specific aspects of the symptomatology. Psychological theories of schizophrenia look at cognitive, behavioural and psychodynamic factors to explain schizophrenic symptoms while biological theories look behind genetic and neurochemical factors. While they may be different ways of looking at the same problem, there are similarities between both theories.

Firstly, biological theories argue that there is a genetic component to schizophrenia which can be explained by genes. Given that human beings are shaped as much by genetics as by other factors. The hereditary component of schizophrenia was demonstrated by studies by McGuffin et al (1997) done on MZ and DZ twins to determine their concordance rates when it came to psychotic disorders including schizophrenia and major depression. The study showed that concordance rates for schizophrenia for MZ twins was 44.%, 12.08% for DZ twins and 2.84% for grandchildren illustrating the genetic likelihood of inheriting schizophrenia for persons that similar genetic makeup such as MZ twins (McGuffin and Katz 1989; McGuffin et al., 1997).

But a concordance rate of 44.3% is less than 50% which means half a chance of inheriting schizophrenia even for MZ twins that share 100% genetic material. This is because the other 50% is not genetic but rather down to other factors such as gene interaction with the environment, a key point genetic theory shares with psychological theories regarding the role of the environment in explaining schizophrenia. Psychological theory for instance states that one environmental factor that contributes to cognitive bias is social factors such as isolation and trauma, while biological theory also states that gene interaction with a traumatic environment can lead to gene expression that contributes to cognitive dysfunction characteristic to psychosis.

The second similarity between both biological and psychological theories is their attribution to the role of neurochemical imbalances in the brain and schizophrenia. They both attribute dopamine imbalances in the brain as behind some of the psychotic symptoms behind schizophrenia e.g. hallucinations, anxiety and depression. The only difference is that while biological theory asserts neurochemical imbalances are caused by natural abnormalities in dopamine activity, psychological theory attributes artificial hallucinogenic drugs as the cause of dopamine imbalance (Davis et al 1991).

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Contrasts between psychological and biological explanations of schizophrenia

Nevertheless, while a comparison of psychological and biological explanations of schizophrenia does show similarities in their explanation, they do have a lot more contrasts and variances. The first contrast is that psychological theory places emphasis on cognitive processes that function in a biased way especially negatively...




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Bentall, R. P. (1990) “The illusion of reality: a review and interpretation of psychological research on hallucinations” Psychological Bulletin, 107:82–95. 

McGuffin, P. and R. Katz (1989) "The genetics of depression and manic –depressive disorder" British Journal of Psychiatry, 155: 294-304



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Outline and evaluate two or more biological explanations for schizophrenia

similar environments. Even when the adopted environments are similar, there is still the shared experience in the womb and at birth so pre-natal viruses or birth trauma may have had an effect. Overall the evidence suggests that genes play a part but nature cannot completely explain schizophrenia as there is not a 100% concordance rate. Nurture needs to be considered and the evidence suggests environmental factors must play a part.

Without knowing the specific genes involved we can’t

 explain how these contribute to the development of schizophrenia, however the current advances in research into the mapping of genes may bring more insight to the process. Schizophrenia has also been explained by brain chemistry. There are certain chemical abnormalities that can be observed to produce schizophrenia-like states. For example, prolonged use of LCD or ant abuse which is a drug used for alcoholism. Genetics may have an effect through body chemistry. The original dopamine hypothesis suggested that schizophrenia is associated with an excess of the neurotransmitter dopamine causing neurones to fire too often and transmit too many messages. A more recent version says that rather than an excess of dopamine it is an excess of dopamine receptor cells (D2 receptors) that lead to more firing and excess messages. Dopamine neurones play a key role in guiding attention so disturbances in this process may lead to the problems of attention and thought found in people with schizophrenia.  Antipsychotic drugs block the activity of dopamine in the brain and eliminate symptoms such as hallucinations and delusions (they are used to treat many schizophrenics); therefore this provides strong evidence for dopamine being a significant contributory factor for schizophrenia. It reinforces the fact that there may well be a causal relationship between dopamine message overload and schizophrenia. However, not all schizophrenic patients respond to these drugs. L DOPA is

a drug used to treat Parkinson’s di

sease. It increases dopamine levels. It


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