Biological Explanations

• What are the 2 parts of The biological explanation for schizophrenia?

  Genetic basis

  Neural correlates
• What studies are part of the genetic basis?

  Family studies

  Twin studies

  Adoption studies
• What is a family study for schizophrenia?

  Gottesman 1991
• What did Gottesman find?

  46% risk of developing Sz if both parents have it

  13% risk if one parent has it

  9% risk if a sibling has it
• What is concluded about schizophrenia from family studies?

  Closer degree of genetic relation means the greater the risk of developing schizophrenia
• What is a twin study for schizophrenia?

  Joseph 2004
• What did Joseph et al find?

  40.4% concordance rate in monozygotic twins & 7.4% concordance rate in dizygotic twins when assessing for schizophrenia
• What do recent twin studies suggest about schizophrenia‘s concordance rates?

  It is lower as newer studies are more methodologically ‘sound’.
• What is an adoption study for schizophrenia?

  Tienari et al
• What did Tienari et al?

  11/164 adoptees with biological schizophrenic mothers had schizophrenia

  4/197 control adoptees had schizophrenia
• What is a candidate gene?

  Genes that may contribute to a disorder
• What is polygenic?


  When there are multiple genes involved in causing a disorder
• What are the candidate genes for schizophrenia responsible for?

  Code for neurotransmitters such as dopamine
• Who identified candidate genes for schizophrenia?

  Ripke et al
• How many genetic variations did Ripke et al identify for schizophrenia?

  108
• What did Ripke et al do?

  Combine all previous genome-wide studies for schizophrenia with 37000 Ps and 113000 controls
• What is aetiologically heterogeneous?

  When several factors in different combination can lead to a disorder developing
• Is schizophrenia aetiologically heterogeneous?


  Yes
• What do neural correlates include?

  Brain Structure

  Dopamine Hypothesis
• What parts of the brain are associated with schizophrenia?

  Pre-frontal cortex

  Basal ganglia
• What is the pre-frontal cortex responsible for?

  Thoughts & logical thinking
• What is different in the pre-frontal cortex of schizophrenics?


  Low activity in pre-frontal cortex
• What is different in the basal ganglia of schizophrenics?

  Larger in Schizophrenics
• What does dysfunction in basal ganglia explain?

  Motor dysfunction
• What does dysfunction in the pre-frontal cortex explain?

  Illogical delusions
• What did Allen et al 2007 study?

  Scanned Ps with auditory hallucinations to study positive symptoms of schizophrenia
• What did Allen et al find?

  Lowers activity levels in temporal gyrus & cingulate gyrus
• What is different between the original & updated dopamine hypothesis?

  Updated hypothesis differentiates positive & negative symptoms
• What does the original dopamine hypothesis state?

  Messages from neurones transmit dopamine too easily (trigger happy) for Schizophrenics
• How are neurones transmitting dopamine too easily?

  High levels of D2 receptors mean there is more dopamine binding
• What type of symptoms does the original dopamine hypothesis explain?

  Positive symptoms only
• Who developed the updates dopamine hypothesis?

  Davis & Kahn 1991
• How does the updated dopamine hypothesis explain positive symptoms?

  High dopamine in subcortical areas of the brain
• How does the updated dopamine hypothesis explain negative symptoms?

  Low levels of dopamine in the pre-frontal cortex
• What is evidence for the updated dopamine hypothesis ?

  Patel et al
• What did Patel et al find?

  Low levels of dopamine in pre-frontal cortex of schizophrenics when compared to non-schizophrenics
• What did Patel et al use?

  PET scans
• What did Wang & Deutch do?

  Induced low dopamine in rats

  Caused cognitive impairment
• What did Wang & Deutch show?

  Congruence with the dopamine hypothesis & proof that it is useful as olanzapine reversed the induced effects
• What did Tienari et al 2004 do?

  An adoption study with biological schizophrenic parents ti show the greater risk