Biological Explanations For Schizophrenia

Question 1

What are the 3 biological explanations for schizophrenia?

Answer 1

1) Genetic factors
2) The dopamine hypothesis
3) Neural correlates

Question 2

State the findings for Gottesman’s study on families?

Answer 2

• Children with 2 schizophrenic parents = 46%
• Children with 1 schizophrenic parent = 13%
• Children who’s sibling has schizophrenia = 9%

Question 3

State the findings from Joseph’s (2004) study on Twins

Answer 3

-MZ more concordat (similar) than DZ so greater similarity is due to genetics

• MZ=40.4%
• DZ=7.4%

Question 4

State Tienari et al (2000) findings on adoption studies

Answer 4

• 11/164 adoptees who’s mum has schizophrenia also received schizophrenia = 6.7%
• Just 4/197 control adoptees (2%) had it, with no mother who had schizophrenia

Question 5

(A03 Genetic factors)

How is this reductionist?

Answer 5

P: Reductionist
E: Genome project has increased understanding of the complexity of the gene > Now recognised genes have multiple functions > Schizophrenia is a multi factorial trait as it is the result of multiple genes and environmental factors
E: suggests that the research into gene mapping is over simplistic as schizophrenia is not due to a single gene

Question 6

(AO3 Genetic factors)

What is the methodological problem with this factor?

Answer 6

P: Weakness = methodological problems
E: Family, twin and adoption studies must be considered cautiously because they are retrospective, and diagnosis may be biased by knowledge that other family members who may have been diagnosed
E: This suggests that there may be problems with demand characteristics

Question 7

(AO3 Genetic factors)

Is schizophrenia due to nature or nurture?

Answer 7

P: Weakness = nature vs nurture
E: difficult to separate, concordance rates are not 100% > predisposition - diathesis stress model - more likely to get the disorder
E: Suggests that the biological account cannot give a full explanation of the disorder

Question 8

What does the term “dopamine hypothesis” suggest?

Answer 8

Claims that an excess of the neurotransmitter dopamine in certain areas of the brain is associated with the positive symptoms of schizophrenia

Question 9

How does the dopamine neurotransmitter act in individuals with schizophrenia?

Answer 9

Schizophrenics have high levels of D2 receptors ok receiving neurons, resulting in more dopamine binding and therefore more neurons firing

Question 10

Name a drug that increases dopaminergic activity and it’s function

Answer 10

Amphetamine is a dopamine agonist. It stimulates the nerve cells containing dopamine and floods the synapse with the neurotransmitter.

Question 11

Name the type of drugs that decrease dopaminergic activity

Answer 11

Antipsychotics are dopamine antagonists. They block the activity of dopamine In the brain. It reduces symptoms such as hallucinations and delusions.

• shows important role of dopamine in this disorder

Question 12

Who proposed the revised dopamine hypothesis?

Answer 12

Davis and Kahn (1991)

Question 13

What does the revised dopamine hypothesis say about positive symptoms m?

Answer 13

Positive symptoms are due to excess dopamine in the mesolimbic pathway

Question 14

What does the revised dopamine hypothesis say causes negative and cognitive symptoms?

Answer 14

A deficit of dopamine in areas of the prefrontal cortex (mesocortical pathway)

• e.g PET scans show reduced dopamine in dorsolateral prefrontal cortex of schizophrenic patients compared to normal controls

Question 15

(AO3 The dopamine hypothesis)

What is a weakness of the dopamine hypothesis?

Answer 15

P: Weakness = biologically deterministic
E: if individual has excessive amounts of dopamine then does it really mean they’ll develop schizophrenia?
E: This suggests that the dopamine hypothesis doesn’t account for free will

Question 16

(AO3 The dopamine hypothesis)

What is a strength of the dopamine hypothesis?

Answer 16

P: Strength = Evidence from treatment > success of drug treatment
E: Leucht et al (2013) > meta analysis of 212 studies > antipsychotics = better/more effective than placebo in the treatment of positive and negative symptoms, achieved by reducing the effects of dopamine.
E: These findings also challenged the classification of typical and atypical groupings as differences in their effectiveness were only small

Question 17

(AO3 The dopamine hypothesis)

Why are there challenges to the dopamine hypothesis?

Answer 17

P: There are challenges to both the original and revised dopamine hypothesis (Noll 2009)
E: Antipsychotics don’t alleviate hallucinations/delusions in 1/3 people
Also hallucinations : delusions are present despite levels of dopamine being normal
E: Suggests other neurotransmitter systems acting independently of the dopaminergic system may also produce the positive symptoms associated with schizophrenia.

Question 18

State what the term “neural correlates” means

Answer 18

They are changes in neuronal events and mechanisms that result in the characteristic symptoms of a behaviour or mental disorder

Question 19

What are the specific brain areas included in the neural correlates factor?

Answer 19

1) The Prefrontal Cortex

2) The hippocampus

Question 20

What is the role of the prefrontal cortex in schizophrenia?

Answer 20

• The prefrontal cortex is the executive control
• It is impaired in schizophrenic patients
• Cognitive symptoms of schizophrenia result from deficits within the PFC and it’s connections with other areas of the brain, particularly the hippocampus

Question 21

What is the role of the hippocampus in schizophrenia?

Answer 21

• Is an area in the brain located in the temporal lobe
• Deficits in the nerve connections between the hippocampus and PFC have been found to correlate with the degree of working memory impairments, a central cognitive impairment in schizophrenia
• Hippocampal dysfunction can influence levels of dopamine release in the basal ganglia indirectly affecting the processing of information in the PFC

Question 22

What effect does grey matter have on schizophrenia?

Answer 22

• Reduced grey matter especially in the temporal and frontal lobes
• Those with negative symptoms have enlarged ventricles (nearby or parts of the brain being damaged)
• Cannon et al > schizophrenic = reduced grey matter and enlarged brain ventricles compared to normal individuals

Question 23

What effect does white matter have on schizophrenia?

Answer 23

• Research (e.g Du et al 2013) has found reduced myelination of white matter in schizophrenics compared to normal controls. Particularly the case in the neural pathways between PFC AND HIPPOCAMPUS

Question 24

(AO3 Neural correlates)

What is a strength of AO1 neural correlates?

Answer 24

P: Strength = Research support for grey matter deficits > meta analysis by Vita et al
E: 19 studies - compared schizophrenics with healthy controls > reduced grey matter, specifically to discrete cortical areas in the frontal, temporal and parietal lobes
E: This loss of grey matter was especially active in the first stages of the disease, consistent with the relatively early onset of schizophrenia (late teens/early 20s)

Question 25

(AO3 Neural correlates)

What is another strength of AO1 neural correlates?

Answer 25

P: strength = treatment for neural correlates = prevention of later stages of disorder due to wake intervention
E: North American Prodrome Longitudinal Study ( Addington et al 2015) > neuroimaging, to predict who will develop schizophrenia.
E: Can therefore treat early and risk patients before psychosis develops