CONTENTS - 1 Family study, 1 Twin study, 1 Co Twin Study - AO1 | 1 AO2 of Fam, 1 AO2 of Twin, 1 AO2 of Co Twin
Family - Kety et al - Longitudinal study in Denmark. Started in 62, followed up in 74 and 89. 207 children whose mother's had diag of schiz. (High risk) - matched with children with mother's without diag of schiz (Low risk) (Matched on age, gender, parental socio-economic status and urban/rural residence. 35% of high risk group developed schiz or schizotypal personality disorder - compared to 6.9% of low risk group.
Twin study - Studies have consisistently found conc rates higher for MZ twins than DZ twins - Gottesman and shields (72) - conc rate of 42% for MZ twins and 9% for DZ twins
Co-twin (Separated at birth)- Cardno 99 - Maudsley twin register - 40% conc rate in MZ twins - 5.5% in DZ twins.
Family AO2 - Longitudinal study carried out by Erlenmeyer-Kimling et al carried out in New York - found similar results to Kety
Twin AO2 - None of the Twin studies have completely separated environment and genes - not necessarily testing the correct thing
Co Twin - More effective than the idea of a normal twin study - more effective in isolating the variables. Supported by Gottesman - Conc rates for MZ twins sep at birth as high as MZ twins raised in same environment
Other Bio Explans
Viral explanation of schiz
Has been theorised that Schiz is caused by damage to the brain during prenatal stages of child development - 2nd trimester, when brain is forming crucial connections
Study - Torrey - saw that significantly more schizophrenics born during late winter/early spring - suggests is result of virus affecting prenatal development. More abundance of virus - lower immune system due to cold?
O'Callghan - increased risk of developing schiz for those who were in 5th month of foetal development during '57 flu epidemic
Other Bio Explans
Based on idea that schiz is caused by imbalances of hormones, etc in brain of schizophrenics
Biological evidence - AO1 - porst mortem studies on brains of schizophrenics - show higher than average levels of dopamine - suggests link between too much dopa being produced and schizo
Amphetamine users - have excess of dopa due to the drug, producing sypmtoms similar to schizophrenics in normal people, making symptoms worse in schizophrenics
AO2 - Davis discussed possibility of schizophrenia being caused by overly sensitive dopamine receptors or increased number of receptor sites.
AO2 - Lindstroem - radioactively labelled L-DOPA chemical, which produces dopamine - PET scans showed that L-DOPA was taken up more quickly in schizophrenics than non.
CONTENTS - Family - EE AO1, Cognitive AO1 x2, Family Double Bind
Expressed Emotion - Linzen - schizophrenic patients returning to families with communication styles high in criticism 4x more likely to relapse compared to those returning to family with low EE. Aso found positive correlation between amount of time spent wiht family members in high EE familie and the likelihood of relapse
Double Bind AO1 - Bateson - ideas behind the theory - Suggested parents using contradictory patterns of communication more likely to have schizo children. - When words do not match body language, tone or actions - child doesn't know how to feel, beginning to withdraw and disbelieve their own perceptions of reality.
Cognitive AO1 - Helmsley 93 - Believes schiz is caused by breakdown in relationship between info already stored in memory (schema) and new incoming sensory info. Schemas are not activated in the usually unconscious process in schizes - means that the memory mechanisms also mean internal thoughts are not regonized as coming from memory and therefore experienced as auditory hallucinations. - Possible that these may be passed through genes.
Psych Explans AO2
EE AO2 - Vaughn and Leff 76 - supports findings wiht 51% relapse in high EE homes compared to 13% relapse in low EE homes - also found relapse rates increasing as face to face contact with high ee relatives increased.
EE AO2 - Vaughn and Leff also found that those who went to work or attended a day dentre were significantly less likely to relapse
Double Bind AO2 - Bateson carried out interviews with schizophrenics and their families, observing patterns of communication to back up his theory - findings supported that of his theory - though this may be interpreter bias
Double Bind AO2 - Berger found that schizs recalled more double bind statements from their families than non schizos.
Cog AO2 - Bentall - Asked ppts to read ou t words or think of words themselves - Week later asked to identify which words they had read, which ewere new and which they had thought of themselves. Schiz group did significantly worse