BIOLOGICAL EXPLANATIONS OF SCHIZOPHRENIA (POLYGENETIC (SZ is classified as…
BIOLOGICAL EXPLANATIONS OF SCHIZOPHRENIA
There are two biological explanations of schizophrenia:
Neural Correlates (patterns of structure and activity in the brain which are linked to symptoms of schizophrenia)
Gottesman is one of the key psychologists associated with biological explanations of schizophrenia.
The concordance rate of SZ for identical twins is 48%. This statistic can be criticised because we would expect concordance rates to be 100% among identical twins If one's genetics was the only influential factor over our behaviour. Therefore, it can be criticised for being reductionist.
The concordance rate of SZ for fraternal twins is 17%.
The concordance rate of SZ for siblings is only 9%.
His research findings are supported by Kety and Ingranham who found that the prevalence rates of SZ were 10 times higher among genetic relatives compared to adoptive relatives.
SZ is classified as a polygenetic disorder because multiple genes are thought to be linked together.
108 candidate genes are associated with SZ
Ripe discovered that there were 108 candidate genes linked with SZ. He compared 37,000 patients (they had SZ) with a control group of 113,000.
The most recent gene to be established is the 'Neuregulin' gene
The Neuregulin gene is responsible for the re-wiring of the brain.
The Neuregulin gene was discovered in during a study which followed a group of 163 young people. 100% of those who possessed the neuregulin gene went on to develop SZ, compared to only 40% of those who did not possess the gene.
Neural correlates is broken down into two parts:
The Dopamine hypothesis
Synder proposed to hyperdopaminergia hypothesis: High levels of dopamine may be associated with the experience of speech poverty and the experience of auditory hallucinations.
Davis proposed the hypodopaminergia hypothesis: Low levels of dopamine may be associated with negative symptoms, such as loss of thinking and decision making.
Areas of the brain
PRE-FRONTAL CORTEX: This is responsible for organising our thoughts and helping people to think logically. In schizophrenics, this area of the brain has a lower level of activity so it is associated with: delusions, disorganised SZ and racing thoughts.
THE VISUAL AREA: Responsible for processing information received from the eyes. In schizophrenics, the level of activity in the visual area is the same as the level of activity in a healthy individual. It is however associated with hallucinations.
THE AUDITORY AREA: Responsible for processing information received from the ears. The auditory area has the same level of activity in a schizophrenic person compared with a healthy individual.
THE BASAL GANGLIA: This is responsible for movement and thought. It thus separates us from animals because despite animals being able to move, they do not have the same thought processes as humans. In schizophrenics, this area of the brain is larger so may lead to movement dysfunction (catatonic behaviour).