biological explanation of schizophrenia

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  • Created by: becky
  • Created on: 06-06-14 17:28

Biological explanations of Schizophrenia (Sz)

Genetic Hypothesis

Sz has shown to run in families:

There is a 1% for the general population developing Sz

48% risk of Mz twin having Sz if the other does

17% risk for Dz twin if the other has Sz

One parent= 17% risk

Both parents= 46% risk

Twin studies

Twin studies have compared the concordance rates between Mz and Dz twins. Most research finds higher concordance rates between Mz twins and Dz twins

:) Cardno- used the Maudsley Twin register and found a 26.5% concordance rate between MZ twins and 0% concordance rate between Dz twins

x- However different researchers have found there to be different areas of the brain that are effected

x- Better control studies tend to find lower concordance rates

x- It is impossible to tease out environmental factors, particularly between Mz twins who tend to be treated more similarly than Dz twins

Adoption Studies

These allow researchers to investigate genetic links in those who have Sz mothers but who have been brought up by an adoptive family without a history of Sz.

:) Tienari’s Finnish Adoption Study- found a 10% rate of Sz in those with Sz mothers and only a 1% rate of those whose biological mother were non-Sz (the general population risk)

:) This provides strong evidence that there is a genetic influence in Sz

x- There tend not to be any strong concordance links suggesting other factors to have a major influence

Biochemical explanations

The concept behind this explanation is that those with Sz have biochemical abnormalities in the brain.

This focuses on neurotransmitter activity and particularly the role of dopamine

Dopamine hypothesis

Early research believed Sz to be caused by excessive eproduction of Dopamine

:) Post-mortems would find higher concentrations of dopamine in those with Sz

:) Amphetamine Psychosis shares similar symptoms with Sz. Amphetamines would release dopamine and they were found to therefore worsen the symptoms of Sz


Today’s research leads on the basis that Sz may be cause by more dopamine being utilised rather than there being more…


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