Biological explanations

• What are neural correlates?

  Specific brain areas
• Which brain area is impaired in schizophrenia?

  Prefrontal Cortex (PFC)
• What cognitive functions is the Prefrontal Cortex involved in?

  Planning and reasoning
• What are deficits in the PFC linked to in schizophrenia?

  Cognitive symptoms
• What kind of changes are observed in the hippocampus of schizophrenia patients?

  Anatomical changes
• Deficits in connections between the hippocampus and PFC are linked to what impairments?

  Memory impairments
• What happens to the volume of grey matter in schizophrenia, especially in temporal and frontal lobes?

  Reduced volume
• According to Gotoa et al (2008), what does hippocampal dysfunction influence?

  Levels of dopamine
• What happens to ventricles in schizophrenia?

  Enlarged ventricles
• What did Cannon et al (2014) find regarding grey matter loss in individuals at high clinical risk who developed schizophrenia?

  A steeper rate of grey matter loss
• What happens to myelination in white matter, especially between PFC and hippocampus, in schizophrenia?

  Reduced myelination
• What is affected by reduced myelination in schizophrenia?

  Information processing
• What type of control is the PFC involved in?

  Executive control
• Neural correlates: The dopamine hypothesis

  Excess dopamine causes schizophrenia symptoms. Drugs increasing dopamine (like amphetamines) can induce schizophrenic symptoms. Antipsychotics reduce dopamine, alleviating symptoms.

   

  Revised hypothesis: Excess dopamine in subcortical areas (mesolimbic pathway) causes positive symptoms. Deficit of dopamine in prefrontal cortex (mesocortical pathway) causes negative symptoms. Patel et al (2010) found lower levels of dopamine in dorsolateral prefrontal cortex of schizophrenic patients.
• Genetic factors: Adoption studies

  Tienari et al. (2000) in Finland: Adoptees with schizophrenic biological mothers: 6.7% developed schizophrenia. Adoptees with non-schizophrenic biological mothers: 2% developed schizophrenia. Concluded that genetics decisively confirms liability to schizophrenia.
• Genetic factors: Family studies

  Schizophrenia is more common among biological relatives. The closer the genetic relationship, the higher the risk. Gottesman's study: Children with 2 schizophrenic parents: 46% concordance. Children with 1 schizophrenic parent: 13% concordance. Siblings: 9% concordance.
• Neural correlates: Evaluation 1

  Evidence from Drug Treatment

  * Back:

     * Leucht et al. (2013) found antipsychotics more effective than placebos, supporting the dopamine hypothesis.

     * Challenges typical/atypical antipsychotic classification, as effectiveness differences were small.

     * This suggests dopamine plays a key role in schizophrenia.
• Neural correlates: evaluation 2

  Challenges to the Dopamine Hypothesis

  * Back:

     * Noll (2009) argues antipsychotics don't alleviate symptoms in 1/3 of people.

     * Some have symptoms despite normal dopamine levels.

     * This suggests other neurotransmitters may be involved in positive symptoms.
• Neural correlates: Evaluation 3

  Challenges to the Dopamine Hypothesis

  * Back:

     * Noll (2009) argues antipsychotics don't alleviate symptoms in 1/3 of people.

     * Some have symptoms despite normal dopamine levels.

     * This suggests other neurotransmitters may be involved in positive symptoms.