Critically Consider The Contribution Of Biological And

Environmental Factors For Schizophrenia Essay, Research Paper

Critically Consider the Contribution of Biological and Environmental Factors for Schizophrenia

Schizophrenia is a common form of mental disorder, effecting 40-50% of psychiatric patients. Symptoms include hallucinations, delusions and disturbance of thought. Although sufferers do suffer a split in their mind- from themselves and the world around them, schizophrenia must not be confused with multiple personality disorder. It is the most serious of disorders in both ICD-10 and DSM-IV and both recognise the four different types of schizophrenia.

Each school of psychology has a theory for the aetiology of schizophrenia. The two main areas of thought to what causes the disorder are biological factors and environmental factors.

The biological approach is supported by the medical model in three sectors- the biochemical influence, the genetic influence and the neurodevelopment influence.

The biochemical theory proposes that schizophrenia be caused by chemical imbalances in the brain which, in turn are caused by an excess of the neurotransmitter- dopamine. There is evidence to support this claim. Firstly, post-mortem examinations of schizophrenics do tend to show high levels of dopamine, as found by Iverson in 1979. The problem with this evidence is that the levels of dopamine could indeed be a result of the disorder rather than a cause. The second area of evidence concentrates around the treatment of schizophrenics, drugs such as chlorpromazine work by binding to dopamine receptor sites, again the fact that there is dopamine there to begin with could be a result, not a cause of the disorder. Also, this evidence only tells us that dopamine is important for the action of anti-schizophrenic drugs, it doesn t tell us that high dopamine levels is the sole cause, or even cause of the disorder. The final piece of evidence for the dopamine hypothesis is that drugs such as amphetamines, LSD and L-dopa do increase the amount of dopamine in the brain, they also cause the user to portray schizophrenic behaviour. Osmond and Smythies, 1976 who noticed the similarities between the effects of hallucinogenic drugs and schizophrenic behaviour, support this. As does Murray, he found traces of the hallucinogen- DMT in schizophrenic s urine. Despite being fairly impressive, the dopamine hypothesis is a very reductionist argument, the dopamine is not proven to be a direct influence to schizophrenia. Crow et al criticises the theory using Kraepellin s positive and negative symptoms. He states that negative effects such as diminished social interaction and slight speech are not affected by the treatments given. Only positive symptoms- hallucinations, delusions etc. are helped. This suggests that these are the only symptoms that may be caused by dopamine.

The genetic theory appears to carry more weight than the other biological theories. A person has a 1in a 100 chance of becoming schizophrenic, if one parent has schizophrenia then the chances increase to 1 in 5 chance and if both parents have had schizophrenia the likelihood further increases to a 1 in 2 chance. There has been extensive research on twins and adoption studies.

Most research has been in the medium of concordance rates between identical (MZ) twins and between non- identical (DZ) twins. The first of these tests was carried out by Kallaman in 1938, he found that MZ twins had concordance rates of 86.2% and DZ twins had rates of 14.5%. This makes sense as identical twins share the same, identical genes. However, he has been heavily criticised, the experiments were carried out long before ICD and DSM were introduced, therefore subjects may not have bee correctly diagnosed. There was also no scientific way for Kallaman to distinguish between MZ and DZ twins, he could have been biased. There is also evidence of false hospital records and evidence that Kallaman tested twins who had not suffered any schizophrenic symptoms. There have been supporters but there has never bee concordance rates as high as Kallaman s. In 1966 Gottesman and Shields studied 57schizophrenics with twins in London between 1948-64. They found a rate of 48% for MZ twins and just 9% for DZ twins. The latest is Fischer in 1973 in Denmark; they found a broad concordance rate of 48% in MZ s and 20% in DZ s. Although rates vary, it is clear that generally they reduce in time, this is due to the introduction of DSM-IV and ICD-10, it also casts doubt on how reliable the rates in the early experiments were. Heston discovered that if an MZ twin had schizophrenia there was a 90% chance that the other twin would have a mental disorder, be it schizophrenia or not. Environmentalists argue that this is due to twins having the same upbringing under the same circumstances. This problem has been over-ruled, as there have been studies of twins separated at birth who still both have schizophrenia.

The other type of study to prove the genetic theory is adoption studies. Heston has studied adopted children born to schizophrenic mothers but raised by non-schizophrenic parents and compared them to children raised by their biological, non-schizophrenic parents. The results were that 10% of the adopted children suffered with schizophrenia and none of the biologically raised children suffered. Kety et al, 1968 showed that there are many flaws in an environmentalist s view of schizophrenia- In Denmark, a list was compiled of adopted children and whether they were or were not schizophrenic. The rate was low in both groups but of the children that were schizophrenic- 21% had schizophrenic, biological mothers. This suggests that schizophrenia is genetic. An environmentalist would believe it was how the children were brought up in their surrogate families that would determine whether or not they ever suffered.

There is a lot of evidence to support the genetic theory, however it cannot be proven as there is uncertainty as to which gene it is that causes the disorder. There have been breakthroughs but each one has been undermined in the light of new evidence.

There is also the neurodevelopment theory, which blames brain damage for schizophrenia and therefore claims to have evidence that schizophrenia is a brain disease. Harrison has shown evidence of schizophrenics undergoing difficult births and a temporary lack of oxygen to the brain. Bracha, 1991 also suggests that it occur during the time that the child is in the mother s womb. He has evidence suggesting that one MZ twin sufferer is more likely to have hand deformities than the other. The hands are developed in the second trimester of pregnancy and could be caused by a viral infection.

The evidence for neurodevelopment disorders is very inconclusive and in areas contradicts itself.

The other side of schizophrenia is the environmentalist view, although there is little evidence to point to an actual trigger but there have been suggestions;

Strole et al blame poverty, he found that the highest rates of schizophrenia are in inner-city areas and is supported by Clark who found a positive correlation between schizophrenia and low status jobs. In this case it could be the fact that a person is schizophrenic which is stopping them getting a high status job, not vice-versa. Clark uses a correlation, which are often put down to coincidence rather than fact.

Bateson supports R.D. Laing s view that the family is to blame. He says that children can be put into intolerable situations called double binds when they are told to do one thing, for example be more affectionate but at the same time told to do the opposite, for example that they are to old to give their parents a hug. Schizophrenia is a way out for these people. Wynne et al in 1977 stated that parents would sometimes refuse to use a word that a child had learnt and understood to be correct and fill it in with another word. This, according to Wynne can be a step towards the development of schizophrenia. This is thought to be a little far-fetched. R.D.Laing says that the society in which we live is the cause of schizophrenia, he gets his message across through writing three books, using existential psychology (where he tries to get inside the mind of a schizophrenic). The first book is called The Divided Self , Laing states that a schizophrenic is insecure and has fears that society will transform him/her into an automata. In his second book, Laing takes Szazs view that schizophrenia doesn t exist as an entity but a tool used by psychiatrists and such professionals to control people whom they see as different and a threat to the society because of their abnormal views. In his third book, which is rarely taken seriously, Laing states the psychedelic vision of schizophrenia, that sufferers are critics of our seemingly mad society and treatment for schizophrenia is just a deterrent to stop them believing such things. R.D.Laing is criticised for underestimating the horror that schizophrenia sufferer s experience.

So the battle between nature and nurture continues, one side believing that a chemical imbalance in the brain or genetics are to blame and the others uncertain about what actually triggers the disorder, it could be down to socio-economic-status, upbringing, the family, the society or life experience. There has been a lot of research and will continue to be large amounts of studies into the aetiology of the disorder but what actually causes it is controversial and more importantly unknown.


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