Biological explanations of schizophrenia
- Created by: Natalie
- Created on: 17-10-13 13:43
View mindmap
- Biological Explanations
- Genetic factors
- Schizophrenia more common among biological relatives of person with schizophrenia (Gottesman, 1991).
- Twin studies - Joseph (2000) pooled data shows concordance rate for MZ twins of 40% and DZ twins 7%.
- Differences in concordance rates may reflect environmental similarity rather than role of genetic factors.
- Environments of MZ twins may be more similar than for DZ twins.
- Use of 'blind' diagnoses produces lower concordance rate for MZ twins, but still much higher than DZ.
- Differences in concordance rates may reflect environmental similarity rather than role of genetic factors.
- Adoption study by Tienari et al. (2000) - if biological mother schizophrenic, 6.7% of adoptees also schizophrenic (2% of controls).
- Schizophrenia more common among biological relatives of person with schizophrenia (Gottesman, 1991).
- Adopted children from schizophrenic backgrounds may be adopted by particular type of adoptive parent, making conclusions difficult to draw.
- Dopamine hypothesis
- Neurons that transmit dopamine fire too easily or too often, leading to symptoms of schizophrenia.
- Schizophrenics - abnormally high levels of D2 receptors.
- Evidence from large doses of amphetamines (dopamine agonist) causes hallucinations and delusions.
- Anti-psychotic drugs - block dopamine and eliminate symptoms.
- Parkinson's disease - treatment with l-dopa raises dopamine levels and can therefore also trigger schizophrenia symptoms.
- Drugs can increase schizophrenic symptoms as neurons try to compensate. Haracz (1982) found elevated dopamine levels in post-mortems of schizophrenics who had taken medication.
- Neuroimaging studies failed to provide convincing evidence for altered dopamine activity in schizophrenics.
- Enlarged ventricles
- Ventricles of person with schizophrenia 15% bigger than non-schizophrenic.
- Display negative rather than positive symptoms.
- May be result of poor brain development or tissue damage.
- Meta-analysis found substantial overlap in ventricle size among schizophrenic and control populations.
- Enlarged ventricles may be due to effects of anti-psychotic medication.
- Genetic factors
Comments
No comments have yet been made