Biological Explanations of Schizophrenia Flashcards
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
