4.3 Biological Explanations For Scizophrenia Flashcards
summarise genetic factors as a biological explanation for schizophrenia
genetic explanations emphasis the importance of inherited factors
family studies - schizophrenia more common among biological relatives of a person with the disorder
twin studies - show higher concordance rate for MZ twins than for DZ twins
adoption studies - Tienari et al. found greater link with biological parents than adoptive parents
summarise the dopamine hypothesis as a biological explanation for schizophrenia
dopamine hypothesis claims excess of dopamine causes positive symptoms of schizophrenia
drugs that increase dopamine (e.g. amphetamines) produce schizophrenic symptoms and drugs that decrease dopamine (antipsychotics) reduce symptoms
revised dopamine hypothesis - includes dopamine underactivity in PFC
summarise neural correlates as a biological explanation for schizophrenia
cognitive symptoms due to impairment in PFC and its connections with other brain regions (e.g. the hippocampus)
individuals with schizophrenia show grey matter deficits and enlarged brain ventricles (Cannon et al. 2014)
reduced myelination of white matter pathways in schizophrenic patients (Du et al. 2013)
evaluate biological explanations for schizophrenia
genetics - MZ twins encounter more similar environments which explains higher concordance rates
adoptees may be selectively placed, suggesting that adoptive parents of children at risk of schizophrenia not typical
dopamine hypothesis - evidence from success of antipsychotic treatments that reduce dopamine activity in the brain
challenges to the dopamine hypothesis - antipsychotics don’t decrease symptoms in everyone and some schizophrenics have normal dopamine levels
research support for influence of grey matter deficits in schizophrenia - from meta-analysis of 19 studies (Vite et al. 2012)
implications for treatment - early detection of neural correlates allows treatment to prevent full development of psychosis (e.g. NAPLS study)
what is meant by biological explanations
emphasises the role of inherited factors and dysfunction of brain activity in the development of a behaviour or mental disorder
what is the dopamine hypothesis
claims that an excess of the neurotransmitter dopamine in certain regions of the brain is associated with the positive symptoms of schizophrenia
what is meant by the term genetics when looking at the occurrence of schizophrenia
inherited factors make certain individuals more likely to develop a behaviour or mental disorder
what is meant by the term neuronal correlates
changes in neuronal events and mechanisms that result in the characteristic symptoms of a behaviour or mental disorder
what is white matter, where is it found?
made up of nerve fibres covered in myelin
found in the brain and spinal cord
why is the purpose of myelin
creates an insulating sheath around nerve fibres and helps to conduct information quickly through the central nervous system, enabling efficient information processing
explain the purpose of the PFC
main area of the brain involved in executive control (i.e. planning, reasoning, judgement)
explain the connection between impairment of the PFC and symptoms of schizophrenia
cognitive symptoms of schizophrenia result from deficits within the PFC and its connections with the other areas of the brain, particularly the hippocampus.
explain the connection between anatomical changes in the hippocampus and symptoms of schizophrenia
deficits in the nerve connections between the hippocampus and PFC have found to correlate with the degree of working memory impairments, a central cognitive impairment in schizophrenia
it’s also been suggested that hippocampal dysfunction might also influence levels of dopamine release in the basal ganglia, indirectly affecting the processing of information in the prefrontal cortex
concordance percentage rates when looking at Gottesman’s family study
children with two schizophrenic parents had a concordance rate of 46%
children with one schizophrenic parent had a concordance rate of 13%
children with a sibling of whom had schizophrenia had a concordance rate of 9%
concordance rates for MZ and DZ twins
MZ = 40.4% DZ = 7.4%
