Biological explanations

• What is a genome?


  It includes all the DNA and the complete set of genetic information for an organism and consists of 23 pairs.
• What is dopamine?


  Its a neurotransmitter that generally has an excitory effect and associated with sensation of pleasure - mood.
• What are candidate genes?


  Gene that's believed to be related to a particular trait like as a disease or physical attribute
• What's a neurotransmitter 


  Its an endogenous chemicals that allows neutrons to communicate with each other throughout the body
• What is a concordance rate


  % of people which both members of a our have a particular attribute.
• Genetic explanation 


  Individual genes are believed to be associated with risk of inheritance. Schizophrenia is polygenic - this means there are multiple genetic factors involved in inheriting schizophrenia. Research also sights that schizophrenia is aetiologically heterogeneous. This means that there is not one set combination of genes which increases the risk of schizophrenia but there are many combinations of genes which can link to the development of schizophrenia.
• Genetic explanation 2

  Ripke et al found that from a study of 37000 schizophrenic patients, there were different genetic combinations thought to have caused schizophrenia.

  Sherrington et al has found a gene located on chromosome 5 which has been linked in a small number of extended families where they have the disorder.

  Miyakawa et al studied DNA from human families affected by schizophrenia and found that those with the disease were more likely to have a defective version of a gene called PP3CC which is associated with the production of calcineurin which regulates the immune system.
• Gene mapping


  describes the methods used to identify the locus of a gene and the distances between genes.
• Dopamine Hypothesis


  The theory that an excess of dopamine in certain areas of the brain contributes to the development of psychotic symptoms in schizophrenia
• Neural Correlates of Schizophrenia


  The specific areas of the brain involved in the functioning and malfunctioning of the brain in people with schizophrenia
• Hyperdopaminergia


  An excess of dopamine in the brain, contributing to psychosis and schizophrenia
• Neural correlations


  Patterns of structure or activity in the brain that occur with a schizophrenic experience. As they occur simultaneously this could lead to us believe that the patterns observed are implicated in causing schizophrenia. Abolition which involved motivation has been associated with one of the main rewards centres in the brain. The ventral striatum is crucial in the anticipation of reward. Jackal et al measured activity levels here and found lower levels of activity in schizophrenics compared to controls. As one decreases the other decreases.
• Negative correlation

  Negative correlation between activity levels and severity of avolition. As activity levels increase, avolition decreases. As activity decreases, avolition increases. Ventral striatum is a neural correlate of negative symptoms.

  Positive symptoms also have neural correlates. Allen et al scanned patients with auditory hallucinations, compared to a control. Lower activation levels were found in superior temporal gyrus and anterior cingulate gyrus of hallucination group. Reduced activity in these parts of the brain is a neural correlate for auditory hallucinations
• What did Fakal et al (198) find in their study regarding dopamine levels in schizophrenic patients?


  They found increased dopamine levels in the left amygdala.
• What does the evidence suggest about dopamine in relation to schizophrenia?


  It suggests that dopamine is not the only neurotransmitter involved.
• What neurotransmitter did Moghaddam & Jovitz (2012) find evidence for in relation to schizophrenia?


  Glutamate.
• What deficiency did Moghaddam & Jovitz (2012) suggest exists in schizophrenics?


  They suggested a deficiency in glutamate function.
• How do drugs like LSD and amphetamines affect individuals with schizophrenia?


  They exacerbate symptoms in schizophrenic individuals.
• What is the mechanism by which LSD and amphetamines induce symptoms in non-schizophrenic individuals?


  They activate dopamine systems in the brain.
• What percentage of patients do antipsychotic drugs reduce symptoms in?


  About 20% of patients.
• How long does it take for antipsychotics to reduce positive symptoms?


  It takes several weeks for antipsychotics to gradually reduce positive symptoms.
• What do antipsychotic drugs do immediately upon administration?


  They begin blocking dopamine receptors straight away.
• What is the mechanism of action for chlorpromazine in treating schizophrenia?


  It works by inhibiting dopamine transmission.
• What is L-dopa and what condition is it used to treat?


  1. dopa is a dopamine synthesis medication used to treat Parkinson's disease.
• What effect can L-dopa have on non-psychotic patients?


  It can induce symptoms resembling acute schizophrenia.
• What did Lindström et al (1999) find in their radioactive labeling study regarding dopamine production in schizophrenics?


  They found that chemicals needed to produce dopamine are taken up faster in schizophrenics compared to controls.
• What implication does Lindström et al (1999)'s finding have regarding dopamine in schizophrenia?


  It implies that schizophrenics produce more dopamine.
• What is one strength of the genetic explanation for schizophrenia?


  It has a strong base of evidence.
• What did Gottesman's family studies reveal about schizophrenia?


  Risk increases with genetic similarity to a family member with schizophrenia.
• What did Pekka Tiehari et al's adoption studies demonstrate?


  Biological children of parents with schizophrenia are at heightened risk even if raised in an adoptive family.
• What was the concordance rate for identical twins in Kikke Hilker's twin study?


  33%
• What was the concordance rate for non-identical twins in Kikke Hilker's twin study?


  7%
• What does Kikke Hilker's twin study suggest about sane people and schizophrenia?


  Sane people are more vulnerable to schizophrenia.
• What is the role of genetic counselling in families diagnosed with schizophrenia?


  • Helps families understand the diagnosis
  • Provides information on reoccurrence risk
  • Aids in making rational choices regarding health
• Limitations of biological explanations

  Reductionist - do not consider wide range of factors that influence human behaviours. Morgan et al - birth complication.

  Correlation - Juckel et al says there's a correlation between low levels of activity and schizophrenia. It's not a causation of it but there's a relationship.

  Polygenic 37000 patients found 108 combinations can't identify 7 specific genes - doesn't account for diathesis stress model.