Biological explanations for Schiz

• Outline the genetic explanation for schizo (family)

  1. The genetic explanation proposes that schizophrenia is inherited and therefore runs in families.
  2. E.g. MZ twins who share 100% of their genetics have a concordance rate of 48% for schizophrenia. Meanwhile, DZ twins who share 50% of their genetics have a concordance rate of 17% for schizophrenia.
  3. These figures, when compared to the 1% risk of schizophrenia in the general population, suggests that the more genetics you share with someone who has schizophrenia, they more likely you are to develop it.
• Outline the genetic explanation for schizo (numerous genes)

  1. The explanation also proposes that schizophrenia is polygenic, meaning it is caused by numerous genes.
  2. These genes are typically linked to dopamine, explaining why people with schizophrenia are often found to have abnormal dopamine activity.
  3. Each of these genes are proposed to increase the risk of developing schizophrenia by a small amount, and each person with schizophrenia can have different combinations of these genes.
• A limitation of the genetic explanation for schizophrenia is that supporting evidence suffers from confounding variables

  MZ twins may have higher concordance rates because they are always of the same sex and look more alike than DZ twins and so they are likely to share more similar experiences - same criticism. This could explain why DZ twins have higher concordance rates than typical siblings despite sharing the same amount of genes (50%). This is a limitation because it suggests there might be an environmental rather than genetic cause for schiz. Therefore questions credibility.
•  further evidence that genetics do play a role in schizophrenia.

   E.g. adoption studies have found that children of people with schizophrenia are at an increased risk of schizophrenia even if they are adopted into a family with no history of schizophrenia. This is a strength as it suggests that genetics, rather than environment, leads to schizophrenia. Therefore adds credibility.
•  limitation of the genetic explanation is that it is too biologically deterministic

  This is because it proposes that schizophrenia is determined by genetics which are out of the individual’s control, so can result in feelings of hopelessness. This is a limitation as it can worsen their symptoms and lead to additional mental health difficulties such as depression. It can also lead to blaming within families whereby relatives may be blamed for passing on candidate genes. This can lead to hostility within families that can worsen schizophrenic symptoms. Therefore questions appropriateness.
• genetic explanation is that it is too biologically reductionist.

  This is because it explains the complex disorder of schizophrenia by reducing it down to genetics. This is a limitation because it fails to consider the impact of additional factors in the development of schizophrenia e.g. a dysfunctional family environment. many psychologists now use the diathesis-stress model which proposes that schizophrenia can only develop if you have a combination of factors (e.g. a vulnerability such as genetic predisposition and a stressor such as family dysfunction). Therefore questions credibility.
• Explain what is meant by ‘neural correlates’ of schizophrenia.

  There is a correlation between abnormalities in brain structure/function and symptoms of schizophrenia.
• Outline the dopamine hypothesis as a neural correlate for schizophrenia. (too much dopamine activity)

  1. Proposes that schizophrenia can result from hyperdopaminergia (too much dopamine activity) in the subcortex of the brain.
  2. This is because there are too many D2 receptors for dopamine to bind to.
  3. As dopamine is an excitatory neurotransmitter, its increased activity makes neurons more likely to fire. This results in positive symptoms e.g. hallucinations and delusions.
• Outline the dopamine hypothesis as a neural correlate for schizophrenia.

  1. The dopamine hypothesis also proposes that schizophrenia can result from hypodopaminergia (too little dopamine activity) in the cortex.
  2. This is because there is reduced binding of dopamine to D1 receptors in the prefrontal cortex.
  3. As this area is responsible for decision making and is near Broca’s area, reduced activity is linked to the negative symptoms of schizophrenia e.g. avolition and speech poverty.
• Outline one other neural correlate for schizophrenia.

  1. Another neural correlate for schizophrenia is enlarged ventricles (fluid-filled gaps in the brain).
  2. These are proposed to be enlarged because there is a loss of brain tissue, particularly in the prefrontal cortex.
  3. The prefrontal cortex plays a role in motivation, planning and decision making so reduced tissue/activity here can be linked to the symptom of avolition.
  4. The prefrontal cortex is also located near Broca’s area (responsible for speech production) and so reduced tissue/activity here can be linked to the symptom of speech poverty.
• A strength of the neural correlates explanation is that it has received supporting evidence.

  research has found that drugs that increase dopamine activity worsen schizophrenic symptoms and can produce schiz-like symptoms. Meanwhile, brain scanning studies have found that ppl with schizo brains are compared to neurotypical controls, there are structural differences in the brains. These include enlarged ventricles and decreased brain activity in areas such as the pre-frontal cortex-strength as it supports the idea that schiz may be caused by atypical brain structure. adds credibility.
• strength of the neural correlates explanation is that it has resulted in practical applications when it comes to treating schizophrenia

  E.g. the dopamine hypothesis led to the use of antipsychotic drugs that work by decreasing dopamine activity in the brain. Such drug therapies are found to be more effective than placebos. This is a strength because if the treatment is effective, then the explanation itself must have merit. Therefore adds credibility.
• a limitation of the neural correlates explanation is that it has received contradictory evidence.

  atypical antipsychotics (that affect various neurotransmitters including serotonin and dopamine) are found to be more effective than typical antipsychotics (that only affect dopamine), especially when treating negative symptoms. This is a limitation of the dopamine hypothesis as it suggests that additional neurotransmitters may play a role in schizophrenia. Therefore questions credibility.
•  limitation of the neural correlates explanation is that it is too biologically deterministic.

  This is because it proposes that schizophrenia is determined by brain abnormalities which are out of the individual’s control, so can result in feelings of hopelessness. This is a limitation as it can worsen their symptoms and lead to additional mental health difficulties such as depression. Therefore questions appropriateness.
• limitation of the neural correlates explanation may be too biologically reductionist

  This is because they are attempting to explain the complex disorder of schiz by reducing it to neurotransmitter/brain structure abnormalities. It's a limitation because it fails to consider the impact of additional factors in the development of schiz e.g. a dysfunctional family environment. psychologists now use the diathesis-stress model which proposes that schiz can only develop if you have a combination of factors (e.g. a vulnerability such as brain abnormalities and a stressor such as family dysfunction)