Biological explanations of schizophrenia Flashcards
What are the 3 biological explanations of SZ?
Genetic factors, neural correlates, dopamine hypothesis
How does the genetic approach explain SZ?
SZ passed through DNA chromosomes through family members. Describes how being related to someone with SZ increases chances of inheriting it.
Outline a family study into genetics and SZ.
Gottesman. Children with 2 schizophrenic parents concordance rate of 46%. One schizophrenic parent 13%. Sibling with SZ 9%.
Outline a twin study into genetics and SZ.
Joseph meta-analysis of all pre-2001 SZ twin studies. MZ concordance = 40%. DZ twins 7%.
Outline an adoption study into genetics and SZ.
Tienari et al. 164 adoptees with SZ mothers: 6% also diagnosed with SZ.
194 control group of adoptees: 2% diagnosed with SZ.
Describe the dopamine (DA) hypothesis.
SZ is caused by abnormally high DA (a neurotransmitter) levels in the brain. Messages from neurons that transmit dopamine fire too easily cause hallucinations and delusions.
Describe two pieces of drug evidence for the DA hypothesis.
L-Dopa raises DA levels and given as Parkinson’s treatment can produce SZ like side effects.
Antipsychotic drugs lower DA levels reduce SZ symptoms.
Describe post-mortem evidence for DA hypothesis.
SZ brains found to have higher DA levels.
Describe two neural correlates of SZ.
Hippocampus: Heckers suggested heightened activity in the hippocampus may lead to many SZ symptoms.
Grey matter loss - SZ patients have less grey matter in temporal and frontal lobes. Less tissue = worse symptoms.
(Could be AO3) Outline the revised DA hypothesis.
Davis and Kahn.
Positive symptoms caused by excess DA in subcortical areas of the brain, particularly the mesolimbic pathways.
(Could be AO3) Who proposed the revised DA hypothesis? Based on what type of evidence?
Davis and Kahn. PET scans of brain - DA levels in SZ individuals and control individuals.
(Could be AO3) What does the revised DA hypothesis suggest about positive symptoms of SZ?
Caused by excess DA in subcortical areas such as the mesolimbic pathways.
(Could be AO3) What does the revised DA hypothesis suggest about negative symptoms of SZ?
Caused by deficit of dopamine in the prefrontal cortex.
(AO3) What is a key issue with biological explanations of SZ?
Cause and effect. Do grey matter deficits cause SZ or are they as a result of the disorder? More difficult to find the root cause. DA is good - but causality is still hard to confirm. Does not reduce validity or reliability, but shows complexity of the disorder.
(AO3) Explain how reductionism applies to the biological explanation of SZ.
Simplifies SZ to only biological causes. Strength is the drug treatments. But biology not the only factor - not 100% concordance in MZ twins. Many causes & disorder is more complex. Diathesis-stress may be a better approach.
