Biological explanations for Sz

Question 1

what does the genetic explanation say about schizophrenia

Answer 1

• multiple gene alleles that increase the risk of developing schizophrenia
• if members of our family have schizophrenia we are more likely to develop schizophrenia
• the more genetic risk alleles a person has, the more likely they are to develop schizophrenia

Question 2

what was tienari et al method for the adoption study on schizophrenia

Answer 2

• study supports the genetic explanation
• the experimental group was adopted children whose biological mothers had schizophrenia
• the control group was adopted children whose biological mothers did not have schizophrenia

Question 3

what were the finding about the adoption study

Answer 3

• children with biological mothers with schizophrenia were more likely to develop schizophrenia themselves
• similarities between child and biological mother were due to genetics
• genetics had more of an influence on schizophrenia development than the environment

Question 4

what are limitation of adoption studies

Answer 4

• they assume that any similarity between biological parent and adopted child is solely down to genetics
• they ignore similarities in environment shared by biological parent and adopted child

Question 5

what are the limitations of Tienaris adoption study

Answer 5

• assume similarities between biological parent and adopted child is solely down to genetics - ignore similarities shared by biological parent and adopted child

Question 6

what is Gottesman family studies

Answer 6

both parents suffer from Sz = 46% chance
1 Sz parent = 13%
sibling with Sz = 9%
the more genetically similar relatives are, the higher concordance rate is found

Question 7

weakness of Gottesman family studies

Answer 7

problem of nature vs nurture. Very difficult to separate the differences. the fact that the concordance rate cannot wholly be explained by genes + could be that the individual has a predisposition to Sz which simply puts them more at risk. This suggests that the biological account cannot give a full explanation of the disorder

Question 8

what did Gottesman find in the twin study

Answer 8

gottesman found that Mz twins have a 48% risk of getting Sz but Dz have a 17% risk rate. Evidence shows the higher the degree of genetic relatives ness higher risk of getting Sz

Question 9

evaluation of Gottesman twin studies

Answer 9

• fail to look at the social class and social psychological difference, between twins
• tend to use small samples
  Joseph (2004) pointed out that Mz twins are treated more similarly that Dz. so still could be a cause of environmental factors

Question 10

Question $3.$ Explain what assumption about the phenotypes expressed by an individual is made in twin studies

Answer 10

Phenotype is the characteristic we express when our genes interact with the environment. Twin studies assume that the environmental impact on phenotype is equal for both monozygotic and dizygotic twins. This means that any difference in concordance between monozygotic and dizygotic twins must be due to their genetic similarity.

Question 11

limitation of adoption in essay format

Answer 11

Adoption studies assume that the biological parent has no environmental influence on the child. However, children are often paired with adoptive parents who come from a similar background and live in a similar area. Therefore, while there is no direct influence, the adopted child may still grow up in an environment similar to how they would have grown up with their biological parent. This is a limitation because adoption studies may be over-exaggerating the genetic influence on the child, because they are ignoring the potentially shared environment between the adopted child and biological parent.

Question 12

what does the neural correlates of schizophrenia say

Answer 12

say that schizophrenia is caused by abnormal brain structure
people with schizophrenia have larger ventricles and smaller frontal cortex

Question 13

what did joseph (2004) point out about twin studies

Answer 13

pointed out that MZ twins are treated more similarly than DZ, so there still could be a cause from environmental factors

Question 14

neural correlates: support study

Answer 14

Torrey conducted MRI scans on people with schizophrenia

Torrey compared scans with people with schizophrenia and people with healthy

Question 15

what are the findings of Torreys brain imaging study

Answer 15

Torrey found that people with schizophrenia had 15% large ventricles than those in the control groups
Torrey study supports the neutral correlates of schizophrenia

Question 16

what are the limitations of the neural correlates hypothesis

Answer 16

• we do not have sufficient evidence to conclude that brain abnormalities cause schizophrenia, because the evidence obtained from MRI studies are correlational (cant establish cause and effect)
• the drugs that patients take to treat schizophrenia may act as a confounding variable in studies of neural correlates
• there are individual differences in the brain abnormalities displayed in patients with schizophrenia- not all patients display enlarged ventricles, study support doesn’t always replicate

Question 17

Sarah was always an eccentric child, who grew into an adult with symptoms consistent with schizophrenia. She was diagnosed in her early 20’s, and was given lots of medication to reduce her symptoms.

However she became skeptical of this diagnosis, and asked for another doctor to take a closer look. The doctor conducted an MRI scan, and was able to show Sarah that she had a brain structure that had similarities with someone typically experiencing schizophrenia (i.e. enlarged ventricles.)

Question $6$. Explain one limitation of studies investigating the neural correlates hypothesis, with reference to the scenario given.

Answer 17

One limitation is that the evidence from these studies is correlational - it does not prove that brain abnormalities are causing schizophrenia, only that there is a correlation between these two factors. For example, taking certain medications could cause a side effect where people develop larger ventricles, which could act as a confounding variable in the research. In Sarah’s case, she may have developed enlarged ventricles after consistently taking the medication she was given after her diagnosis. Therefore, studying people who are already on medication does not necessarily show that they have schizophrenia because of these enlarged ventricles.

Question 18

what are neural correlates

Answer 18

variations in neural structure and biochemistry that are correlated with an increased risk of developing Sz

Question 19

what does dopamine do

Answer 19

involved in processing reward and in controlling attention

Question 20

what are dopamine levels like in people with schizophrenia

Answer 20

• people with schizophrenia have higher levels of dopamine than healthy people
• the neurones with people with schizophrenia generate more electrical activity than those without schizophrenia

Question 21

what does the dopamine hypothesis say

Answer 21

people with schizophrenia have a higher level of dopamine than normal in their mesolimbic system which causes higher activity of neurones in mesolimbic system leading to hallucination’s and delusions

Question 22

what is true according to the revised dopamine hypothesis

Answer 22

• people with schizophrenia have higher levels of dopamine in the mesolimbic pathways
• overactivity in the mesolimbic system causes the positive systems of schizophrenia
• people with dopamine have lower levels of schizophrenia in the frontal cortex
• underactivity causes negative symptoms

Question 23

According to the dopamine hypothesis, which symptoms of schizophrenia are caused by overactivity of the mesolimbic system?

Answer 23

positive symptoms

• hallucinations
• delusions

Question 24

Question $4$. What does the original dopamine hypothesis state about the frontal cortex?

Answer 24

The original dopamine hypothesis did not say anything about the frontal cortex. This came later in the revised dopamine hypothesis.

Question 25

What does the revised dopamine hypothesis state about the frontal cortex?

Answer 25

The revised dopamine hypothesis aimed to explain the previously unexplained negative symptoms of schizophrenia. Focusing on the level of dopamine in the brain, and not on any physical structures, the theory states that low levels of dopamine create underactivity in the frontal cortex, causing negative symptoms such as avolition and speech poverty.

Question 26

what are the dopamine hypothesis support studies: drug studies

Answer 26

show that drugs that increase dopamine eg amphetamines cause hallucinations and delusions in healthy people
but drugs that decrease dopamine decrease the likelihood of hallucinations and delusion occurring in healthy people

Question 27

what are the limitations of the dopamine hypothesis

Answer 27

• Nolls study did additional drug tests
• suggests that high levels of dopamine are not the only cause of positive symptoms
• the study suggests that, for the majority of people, high levels of dopamine cause positive symptoms
• found that 1/3 of patients dopamine reducing drugs did not prevent positive symptoms of schizophrenia

Question 28

why did montcrieff that the evidence supporting the dopamine hypothesis was inconclusive

Answer 28

• drugs that increase dopamine like amphetamine also increase levels of other neurotransmitters, so we cant be sure that increased dopamine that is causing these symptoms
• some post mortem studies reported increased levels of dopamine in the mesolimbic pathway, but other studies reported no difference compared to the control brains

Question 29

Amy was a healthy volunteer in a trial for a new drug, which was a variation of amphetamine. Amy took the drug and doctors recorded the effects it had on her brain activity and behaviour.

Question 1a. Which neurotransmitter, that has been associated with the symptoms of schizophrenia, is this new drug likely to impact in Amy’s brain?

Answer 29

dopamine

Question 30

Amy was a healthy volunteer in a trial for a new drug, which was a variation of amphetamine. Amy took the drug and doctors recorded the effects it had on her brain activity and behaviour.

As a biology student, she knew that if the new drug derived from amphetamine, then it is likely to have an effect on more than just dopamine levels.

Question 3.Which neurotransmitters does amphetamine also increase?

Answer 30

• serotonin

- noradrenaline

Question 31

Question $4.$ Name the researcher that criticised the dopamine hypothesis, by finding that amphetamine also increases noradrenaline and serotonin, alongside dopamine.

Answer 31

Montcrieff.

Question 32

Callum and Jodie both have schizophrenia. As patients in a psychiatric ward, doctors prescribed them drugs that aimed to reduce their dopamine levels. The nurses monitored both Callum and Jodie over several weeks, to see any long-term change in their behaviour.
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Jodie made improvements in her mental state, and nurses noticed how her auditory hallucinations had subsided. Callum on the other hand was still dealing with paranoid delusions and visual hallucinations.
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Question $5.$ Referring back to the scenario, explain one limitation of the dopamine hypothesis.

Answer 32

The dopamine hypothesis assumes that it is the high levels of dopamine in the mesolimbic system that cause the positive symptoms of schizophrenia - hallucinations and delusions. However, drugs that reduce levels of dopamine do not always reduce symptoms. In this example, Callum has not stopped experiencing delusions or hallucinations, despite being on the same drugs as Jodie. Therefore, this suggests that it is not only dopamine that causes positive symptoms of schizophrenia, but that something else must also be involved.

Question 33

Question $6.$ Name the researcher that criticised the dopamine hypothesis, by pointing out that not all people with schizophrenia experience positive symptoms because of high dopamine levels.

Answer 33

noll

Question 34

Noll (2009) conducted a review of drug studies, where drugs were administered to reduce dopamine levels in the brains of people with schizophrenia.
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Question $7.$ Describe the results of the review, and explain what this suggests about the positive symptoms of schizophrenia.

Answer 34

Noll found that across the studies, $33\%$ of patients did not experience a reduction in positive symptoms after being administered a drug that reduced dopamine levels. This suggests that a majority of people experience positive symptoms because of high levels of dopamine in the mesolimbic system. However, this also suggests that high levels of dopamine are not the only cause of positive symptoms, because the drugs were not effective on $100\%$ of patients.

Question 35

Henry has been recently diagnosed with schizophrenia. As a teenager, Henry grew up in a household that put a lot of strain on his mental health. His parent’s often gave Henry contradictory messages, and both parents were often overly critical of him.
Henry was displaying a lot of positive symptoms, including auditory hallucinations and paranoid delusions. The psychiatrist prescribed Henry antipsychotics, which appeared to relieve Henry of his symptoms.

Question 2. Which of the theories from the biological approach best explain Henry’s schizophrenia?

Answer 35

The best biological explanation here is the dopamine hypothesis, because Henry’s antipsychotic medication is able to reduce the occurence of his positive symptoms. The dopamine hypothesis suggests that positive symptoms are caused by high levels of dopamine in the mesolimbic pathway, and antipsychotics are able to decrease dopamine activity.

Question 36

Kimora is a world-class kickboxer, who recently lost a fight. During the fight her opponent hit her around the head more than usual, and Kimora’s coach decides to get a brain scan done just in case of any damage. In the scan, Kimora’s doctor reveals that all is well.

However, the doctor reports to Kimora that she has ventricles much larger than what the doctor would normally see in their patients. The doctors cautions her to take care, but otherwise gives Kimora a clean bill of health.

Question 6. According to the diathesis-stress model, will Kimora develop schizophrenia? Explain your answer. [4 marks]

Answer 36

Kimora has enlarged ventricles which are a known risk factor of developing schizophrenia, meaning she has a diathesis for the disorder. However, the model predicts that just having a predisposition is not enough for Kimora to develop schizophrenia alone, and that she needs to experience a degree of stress to do so. As Kimora is otherwise healthy and happy, she will not develop schizophrenia.

Question 37

Question 3. Explain who was in the experimental group and the control group in the Tienari et al. study.

Answer 37

The experimental group in Tienari et al’s study were children who had been adopted, but whose biological mothers had schizophrenia. The control group were adopted children whose mothers did not have schizophrenia.