Biological Explanations of Schizophrenia

Biological Explanations of Schizophrenia , A level Aqa Psychology

1. Schizophrenia Reliability and Validity of Diagnosis Symptom Overlap Co-Morbidity Inter- Rater Reliability Test-Retest Reliability Predictive Validity Gender / Culture Bias Confirmation Bias

2. Schizophrenia Biological Explanations

3. Schizophrenia Biological Explanations

4. Identical twins 100 Non-identical twins 50 Brother and sister 50 Sisters 50 Father and daughter 50 Father and son 50 Grandmother and grandson 25 Schizophrenia Biological Explanations Grandmother and granddaughter 25 Cousins 12.5 Uncle and niece 25 Aunt and niece 25 Second cousins twice removed 0.781

5. Schizophrenia Biological Explanations Biological explanations for schizophrenia: genetics, the dopamine hypothesis and neural correlates. Outline key assumptions of the biological approach Explain the role of genetics in schizophrenia and how they are studied Evaluate the role that genetics play in schizophrenia. Including research findings Define the term neural correlates Outline the dopamine hypothesis including the revised theory Evaluate the role of dopamine in schizophrenia Introduce the idea of diathesis stress

6. Schizophrenia Biological Explanations predisposition Nature over nurture

7. Schizophrenia Biological Explanations Genetics Heredity: schizophrenia tends to run in families, those who have a close family member with schizophrenia are more likely to develop it themselves. No single ‘schizophrenic gene’ has been identified, it is thought to be different combinations of genes. These make an individual more prone to developing the disorder, it DOES NOT mean they will get it. Ripke - 108

8. How do we study the influence of genetics? Family studies Looking at the concordance rates of features with different family members. Twin studies Looking at the difference in concordance rates between MZ and DZ twins and those raised together or apart. Adoption studies Looking at the concordance rates between biological parents and children and adopted children and parents. Those who are more closely related will have a higher concordance rate for abnormalities, e.g. first degree relatives. Schizophrenia Biological Explanations Genetics KEY TERM: Concordance Rate

9. Schizophrenia Biological Explanations Genetics Family Studies Compares concordance rates of schizophrenia between different family members. Those family members who are more genetically related should have stronger concordance rates. Gottesman p204

10. Schizophrenia Biological Explanations Identical twins 100 Non-identical twins 50 Brother and sister 50 Sisters 50 Father and daughter 50 Father and son 50 Grandmother and grandson 25 Grandmother and granddaughter 25 Cousins 12.5 Uncle and niece 25 Aunt and niece 25 Second cousins twice removed 0.781

11. Schizophrenia Biological Explanations Genetics Twin Studies MZ Should have higher concordance rates because they share 100% of genes DZ Should have lower concordance rates as they only share 50% of genes Compare concordance rates Gottesman 75-91% for severe cases for MZs (see also p204)

12. Schizophrenia Biological Explanations Genetics Adoption Studies Biological mothers Should have a higher concordance rate as they share 50% of genes. Adopted mothers Should have a lower concordance rate as they share no genes Compare concordance rates Tienari

13. Schizophrenia Biological Explanations Genetic mutation Radiation Poison Viruses Natural changes (paternal age)

14. Schizophrenia Biological Explanations Ao3 ‘Schizophrenia runs in families’ What else could cause this result? (PUSH YOURSELF - refer to expressed emotion p206) If adoptive parents know about the biological mother’s schizophrenic history, could this influence their treatment of the child? Should they know this background? Why can this be classed as a socially sensitive area of research? p143 Genetic Counselling

15. Schizophrenia Biological Explanations Ao3 A good way to finish an extended answer on this topic is to include the diathesis stress model – but we will cover that in a few lessons time. If you want to read ahead to work out how this can be used , look at page 214-215.

16. Schizophrenia Biological Explanations Neurotransmission Normal dopamine activity What about in schizophrenia?

17. Schizophrenia Biological Explanations The Dopamine Hypothesis An excess of dopamine in central regions of the brain is associated with the POSITIVE symptoms of schizophrenia e.g ……..

18. Schizophrenia Biological Explanations The Dopamine Hypothesis An excess of dopamine in central regions of the brain is associated with the POSITIVE symptoms of schizophrenia e.g …….. Neurons that transmit dopamine fire too easily Neurons receiving dopamine have too many receptors (D 2 )

19. Schizophrenia Biological Explanations The Dopamine Hypothesis Where has this claim come from? Amphetamines Anti-Psychotics L- Dopa

20. Schizophrenia Biological Explanations The Dopamine Hypothesis L- Dopa For Parkinson’s Disease A neurodegenerative disease, linked to low levels of dopamine Drug that raises dopamine levels, (dopamine agonist) patients have reported hallucinations

21. Schizophrenia Biological Explanations The Dopamine Hypothesis Amphetamines ‘Speed’ ‘Whizz’ ‘Meth’ Dopamine agonist – stimulate nerve cells that release dopamine – flooding the synapse with this NT Large doses can trigger hallucinations and delusions, when abstaining, the symptoms disappear.

22. Schizophrenia Biological Explanations The Dopamine Hypothesis Anti-psychotic Drugs For Schizophrenia Drug that reduce dopamine levels, (dopamine antagonist) blocking the activity of dopamine by reducing activity in neural pathways. They alleviate positive symptoms.

23. Schizophrenia Biological Explanations The Updated Dopamine Hypothesis – Davis and Kahn Over activity of dopamine in subcortex and Broca’s area Under activity of dopamine in prefrontal cortex Evidence from animal and brain-imaging studies (PUSH YOURSELF)

24. Neural Correlates: changes in neuronal events (structure or function) that correlate with abnormal behaviour Schizophrenia Biological Explanations Basal ganglia activity Reduced grey matter density Enlarged ventricle Dopamine activity

25. Neural Correlates: changes in neuronal events (structure or function) that correlate with abnormal behaviour Schizophrenia Biological Explanations PUSH YOURSELF VENTRAL STRIATUM AND AVOLITION Negative Correlation between activity and negative symptoms SUPERIOR TEMPORAL AND ANTERIOR CINGULATE GYRUS AND HALLUCINATIONS Negative Correlation between activity and positive symptoms

26. Schizophrenia Biological Explanations Tenn et al What did they find? How does this support the dopamine hypothesis? However….. Have the effects of adjusting dopamine levels been exaggerated? De Patie

27. Schizophrenia Biological Explanations It is clear that stimulant drugs have an impact on dopamine and at the same time, trigger the same types of symptoms seen in schizophrenia, however, noradrenalin, serotonin and adrenaline are also affected…these other NTs, alongside glutamate are also affected by anti-psychotics … The Dopamine Hypothesis