Biological explanations General genetic link/

To help, use these headings; To Start… You have three minutes to write down as much as you can about the biological approach. To help, use these headings; Basic assumptions of the biological approach about what causes behaviour General evaluation of the basic assumptions/beliefs of the biological approach Main research methods used by the biological approach Evaluation of the above research methods.

Dave Case Study Bullet point a list of possible causes. Dave is 24. Over the last 3 months he has been having visions of aliens walking round him when he goes to work. His speech has become rambling and often his friends cannot tell what he is saying. A few weeks ago Dave was told his old college friend had died and in response he laughed. He has stopped showering regularly and believes that his water system has been poisoned. He has lost a lot of weight as he no longer bothers to cook. His neighbor was worried about Dave when she saw him sitting on the floor in the corner shop grimacing. Dave also has a twin called Darcy. Darcy leads a normal life and lives with her two children and husband. Recently when she has been in the house on her own, she has heard a whispering voice telling her ‘the storm is coming.’ She thinks nothing of it and ignores it until the next time. They had a great childhood apart from a short period of time when they were 4 years old in which their father was taken into the local hospital for 3 weeks. Their mother told them he was suffering from depression. They have since found out it was bipolar or ‘manic’ depression. Bullet point a list of possible causes. Justify why each cause is relevant to Dave’s case (linking back) How likely is it that Dave’s disorder is a product of nature OR nurture? Disorganised Clearly Dave has been experiencing extreme symptoms of Schizophrenia, but why…? What could be the potential causes or triggers of Dave’s Schizophrenia?

Biological explanations Answer the questions below: According to the general genetic hypothesis what increases your chance of developing the disorder? What is the likelihood of developing the disorder in the general population? According to Gottesman (1991), what is the percentage concordance rate of developing the disorder if one parent has the disorder? What 3 research methods are used to determine the genetic influence on schizophrenia? What does concordance rate mean? What were the findings of Gottesman’s study of MZ and DZ twins? What does this suggest about a genetic link in schizophrenia? What were the results of Kety’s adoption study? Why does it help our understanding of genetics to look at children brought up away from their biological parents? Gene mapping (The Genome project) has identified a number of candidate genes for schizophrenia and the disorder could be described as polygenic. What does polygenic mean? What is a candidate gene? There is strong evidence that shows schizophrenia is the result of multiple factors (genes + environment). This is also known as the diathesis stress model. How does the diathesis stress model explain schizophrenia?

Explanation 1: Genetics What does the bar graph to the left show about the relationship between genetics and schizophrenia? Write a conclusion! Challenge: How far do you think this data is valid? Gottesman (1991)

Biological: Always start with ‘Twin Studies’ Why start with Twin studies?….. explain Twin studies (eg. Gottesman, 1991) have identified strong concordance rates: MZ = 0.48 (48% risk) DZ = 0.17 (17% risk) General Population = 0.01 (1% risk) Point of interest: If your partner has schizophrenia your risk is twice that of the general population (2%: can you suggest why?)

Statements “Is my family DNA to blame for my schizophrenia?” “My twin has been diagnosed with schizophrenia, I will get it as well, it is only a matter of time.” Explanation For.. Evidence For… AO3 Evaluation. How useful is the explanation and evidence? Challenge: How far do you agree with these statements? Justify your reasons with evidence if you can.

Bio Explanation 1: Genetics Statement Explanation For.. Evidence For… AO3 Evaluation. How useful is the explanation and evidence? “Is my family DNA to blame for my schizophrenia?” “My twin has been diagnosed with schizophrenia, I will get it as well, it is only a matter of time.”

Explanation 2: Dopamine Hypothesis & Biochemistry What is this and how might it explain Schizophrenia? https://www.youtube.com/watch?v=V1kSIfxBVfU

The Dopamine Hypothesis Dopamine is a chemical substance (neurotransmitter) manufactured in the brain that transmits messages between neurons (brain cells). Dopamine appears to work differently in patients with schizophrenia. Dopamine is particularly important in the functioning of several brain systems that may cause symptoms of schizophrenia – in particular the cortex and subcortex.

The Dopamine Hypothesis Annotate your brain to show: Which areas are involved in the dopamine hypothesis How dopamine leads to schizophrenic symptoms Evidence that supports the dopamine hypothesis of Schizophrenia.

Dopamine, Dopamine, Dopamine… Hyperdopaminergia = Excessive levels of -dopamine in the Subcortex & Broca’s Area Hypodopaminergia = Low levels of dopamine in the prefrontal cortex.

But! How far is the dopamine hypothesis an accurate explanation? Using the sheet of evaluation points provided: Colour code or label the strengths and weaknesses. Annotate each one with commentary about what they suggest about the DH. Form an overall conclusion about the DH – how accurate/valid is it as an explanation of schizophrenia?

Explanation 3: Neural correlates of Schizophrenia. Neural correlates are measurements of the structure or function of the brain that correlate with an experience, in this case schizophrenia. Both positive and negative symptoms have neural correlates. Neural correlates of negative symptoms Avolition involves the loss of motivation and motivation involves the anticipation of a reward with particular parts of the brain being involved in this e.g. ventral striatum. So it follows that if there are abnormalities in these areas then the symptoms can be developed from that. Juckel et al found that there was a negative correlation between the activity in the ventral striatum and the overall negative symptoms. Therefore the ventral striatum is a neural correlate of negative symptoms of schizophrenia.

Neural correlates in positive symptoms Allen et al scanned the brains of patients experiencing auditory hallucinations and compared them to a control group whilst they identified pre-recorded speech as either theirs or someone else's. Lower activation levels were recorded in the superior temporal gyrus and anterior cingulate gyrus in the hallucination group, who also made more errors than the control group. Therefore the reduced activity in these areas are neural correlates of auditory hallucinations. Positive symptoms also have neural correlates. Allen et al (2007) 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.

Evaluation What could be wrong with using correlations to investigate the biological explanation of neural correlates? What about the biological explanation as a whole? How could this be evaluated using GRENADE?

Essay Discuss biological explanations for schizophrenia. (Total 16 marks) Read the answer and complete the following tasks: Identify the paragraph structure and the line of argument What are the strengths? What are the weaknesses? How many marks do you thin the answer was awarded?