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is affected by genetics because of high concordance rates o however, no figure is 100% which implies that although there is a genetic relationship, there are other factors that play a role 2 Adoption studies • Tienari et al (1994) ● o Finnish sample of schizophrenic's offspring given up for adoption was compared blindly with matched controls who were adopted offspring of non sz biological parents ● o adoptive families were were investigated using joint and individual interviews and psychological tests o biological parents were also interviewed and tested o among the 155 index offspring, the percentage of both psychoses and other severe diagnoses was significantly higher than in the 186 matched control adoptees o supports a genetic hypothesis o notable differences between these two groups only emerged in the families which were rated as disturbed o the genetic effect was only manifested as a psychiatric disorder in the presence of a disturbed family environment o impact of disturbed family relations was strongest in the presence of the appropriate genotype Candidates genes a study in 2014 (Ripke et al) found 108 distinct locations on the human genome linked to sz o the genetic locations were not in coding locations but in regulatory regions • Geschwind - most sz linked DNA came into contact with genes known to be crucial to brain development heterogeneity - lots of different genes o important for sz because lots of genes and variations have been associated with sz The biological approach to sz 3 Dopamine hypothesis neural correlate) ● VESICLES CONTAINING ● NEUROTRANSMITTERS • excitatory - more likely to fire • inhibitory - less likely to fire SYNAPTIC CLEFT Copyright © Save My Exams. All Rights Reserved save my exams PRESYNAPTIC MEMBRANE The biological approach to sz POSTSYNAPTIC MEMBRANE NEUROTRANSMITTER hypodopaminergia - low activity of dopamine in the prefrontal cortex (mesocortical pathway) - associated with some negative symptoms • more receptors in some areas and fewer in others causes over or underactivity? sensitivity of receptors causes over or underactivity? RECEPTOR MOLECULES hyperdopaminergia - excessive activity of dopamine in the mesolimbic pathway - associated with positive symptoms 4 Dopamine hypothesis . there is a neural correlate: there is a correlation between brain structure and function and symptoms of schizophrenia ● positive correlation between positive symptoms/ negative symptoms and activity of dopamine does not mean that heightened dopamine activity leads to positive symptoms (could be other way around or something else entirely o if dopamine activity is causing sz, treatments should target dopamine activity by using antipsychotics to reduce positive symptoms o treatment - causation fallacy: the treatment may reduce the symptoms but doesn't necessarily treat the actual cause of the symptoms amphetamines - suggest that large doses of amphetamines can bring on sz-like symptoms because they increase dopamine activity - supports dopamine hypothesis Enlarged ventricles - a neural correlate • ventricle - space in the brain that fills with cerebrospinal fluids SCHIZOPHRENIA IN MONOZYGOTIC TWINS Pair no.2:44 year old males UNAFFECTED The biological approach to sz AFFECTED 5 • over time, people with sz have less brain matter and larger ventricles (post mortem exams) o does this cause sz or does sz cause this? o this is a neural correlate because enlarged ventricles tend to be found in people with sz, suggesting that enlarged ventricles cause sz The biological approach to sz 6