Biological Explanations of Schizophrenia Flashcards
(14 cards)
Genetic factors
Family studies
Twin studies
Adoption studies
Evidence for key role of dopa in Sz
Amphetamines
Antipsychotic drugs
Parkinson’s disease
Family studies
Sz = more common among biological relatives + closer degree of genentic relatedness = greater risk
Children with 2 Sz parents = concordance rate = 46%
Children with 1 Sz parent = 13%
Twin studies
Concordance rate of 40% in Monozygotic + 7% for Dizygotic
However recent, methodologically sound studies = lower concordance rate for Mono
BUT still support genetic position because still higher than Dizygotic
Adoption studies
Help disentangle genentic + environmental factors
Adoptees whose biological mothers had been diagnosed with Sz = 6% diagnosed with Sz compared to only 2% born to non-Sz
Findings showed genetic liability to Sz
The Dopamine hypothesis
Messages from neurons that transmit dopamine fire too easily or too often = characteristics symptoms of Sz
Sz = abnormally high numbers of dopamine receptors on receiving neurons = more dopa binding = more neurons firing
Dopa neurons play key role in guiding attention = disturbances in this process = lead to problem with attention, perception + thought found in Sz
Amphetamines
Dopamine antagonist = stimulating nerve cells containing dopa = synapse flooded with neurotransmitter
Large doses of drug = cause hallucinations + delusions of Sz episode
Antipsychotic drug
Block the activity of dopa in brain
Reducing stimulation of dopa system = eliminate Sz symptoms
Strengthen case for dopa being contributory factor of disorder
Parkinson’s disease
Low level of dopa found in sufferers
People taking drug L-dopa to increase dopa were developing Sz symptoms
Evidence from Treatment
META of studies that analysed effectiveness of antipsychotic treatment compared to placebo
Relapse occured in 55% of Placebo + only 19% of those on drug
Evaluation of Family studies
The fact that Sz runs in fams may be more to do with common rearing = expressed emotion
Negative emotional climate in some families may = stress beyond an indi’s coping mechanisms = triggering Sz episode
Evaluation of Twin studies
MZ twins are treated more similarly, encounter more similar environments + experience more identity confusion than DZ
Reason to believe that differences on concordance rates between MZ + DZ twins reflect noting more than the environmental differences that distinguish MZ + DZ
Evaluation of Adoption studies
US inform potential adoptive parents about the genetic background of children prior to selection
What type of person would want to adopt a Sz child?
Post-mortem studies
Haracz
Found those who showed elevated dopa levels had received antipsychotic drugs shortly before death
Those who hadn’t received medication = norm levels of dopa
Antipsychotics actually increase dopa as neurons struggle to compensate for sudden deficiency
