3 Biological Explanations Flashcards
Family Studies
The Risk of schizophrenia is higher the closer the degree of genetic relatedness. For example, Gottesman showed that children with two schizophrenic parents gave a concordance rate of 46% one schizophrenic parent gave a rate of 13% and siblings gave 9%
Twin Studies
MZ Twins have a concordance rate for schizophrenia of 40.4% and 7.4% for DZ Twins,
Adoption Studies
Separate out genetic and environmental influences 6.7% of adoptees with a biological mother with schizophrenia also had a diagnosis but only 2% of control.
The Dopamine Hypothesis
Too many neurotransmitters is thought to cause schizophrenic symptoms.
Drugs that increase dopamine activity produce hallucinations and delusions,
Drugs that decrease dopamine activity eliminates hallucinations and delusions.
The Revised Dopamine Hypothesis
Too many receptors is thought to cause schizophrenic symptoms.
Evidence comes from neural imaging Schizophrenics have been found to have larger numbers of dopamine receptors in their brains.
Neural Correlation in the prefrontal cortex
The PFC is the main area of the brain involved in executive control This suggests that the cognitive symptoms of schizophrenia are a consequence of a functional impariment
Neural Correlation in the Hippocampus
Suggested that many of the symptoms of schizophrenia may be a consequence of abnormally heightened hippocampal activity
Neural Correlation for Lost Grey Matter
Individuals with schizophrenia have a reduced volume of grey matter in the brain, especially in the temporal and frontal lobes. The greater the tissue loss, the worse the symptoms.
Neural Correlation for Abnormal White Matter
White matter is made up of nerve fibers covered in myelin sheaths, enabling efficient information processing. There is an higher abnormality of white atter in schizophrenic patients than healthy.
Evaluation: Environmental factors may explain family similarities
Schizophrenia runs in families but this may be due to common rearing patterns or negative emotional climate in some families leading to stress and triggering schizophrenic episodes. Also MZ Twins are treated more similarly so have fewer environmental differences than DZ twins
Evaluation: Adoptees May be selectively placed
Adoptive parents are often informed of a genetic background of children, so the allocation to families is not random. Families adopting children of schizophrenic parents may have particular characteristics.
Evaluation: Evidence from treatment with antipsychotic drugs
A Meta-analysis showed that antipsychotic drugs were significantly more effective than a placebo at treating positive and negative symptoms supporting the involvement of dopamine
Evaluation: Challenges to the dopamine hypothesis
Argued that one third of people taking anti-psychotics do not benefit.
Psychotic symptoms can be experienced despite normal dopamine levels so positive symptoms must be produced by another system
Evaluation: Support for grey matter deficit
Meta-analysis of 19 studies showed that patients with schizophrenia compared with healthy controls showed a significantly higher progressive reduction in cortical grey matter volume over time.
Evaluation: Implications for treatment
Research in this area suggests that early detection and intervention might prevent development of the later stages of schizophrenia. The concept of ‘Treatment as prevention’ uses biological assessments to predict who is likely to develop schizophrenia and to develop new treatment and prevention approaches.
