Schizophrenia - biological explanations

Question 1

polygenic

Answer 1

number of genes need to work together

Question 2

aetiologically heterogenous

Answer 2

caused by different combinations of genes in different people

Question 3

candidate genes

Answer 3

many different genes could cause the disorder

Question 4

what did Ripke find from his large scale genome study

Answer 4

108 combinations of genes associated with schizophrenia

Question 5

Gottesman (1991)

Answer 5

monozygotic twins concordance rate = 48%.
dizygotic twins concordance rate = 17%. suggests partially genetic explanation but could be due to similar upbringing and environment?

Question 6

Tienari

Answer 6

longitudinal study on children adopted before age 4 into families with schizophrenic parents. 7.5% adoptees developed schizophrenia compared to 1.5% of the control group

Question 7

Gottesman and Shields (1982)

Answer 7

studied 12 MZ twin pairs that were raised apart. 58% concordance rate, even with different environment, genetics still play role. lacks 100% needed for pure genetic disorder

Question 8

how can schizophrenia be explained genetically with an absence of schizophrenic relatives

Answer 8

mutation

Question 9

what is the mutation explanation of schizophrenia

Answer 9

mutations in sperm DNA due to viral infections, radiation or poision

Question 10

Brown et al (mutation research)

Answer 10

0.7% fathers under 25 had children with schizophrenia and 2% fathers over 40

Question 11

what is the key neurotransmitter involved in schizophrenia

Answer 11

dopamine

Question 12

dopamine hypothesis

Answer 12

Van Rossum (1966). dopamine works differently in schizophrenic patient’s brains. hyperdopaminergia in sub-cortex leads to positive symptoms (auditory hallucinations). near brocas

Question 13

hyperdopaminergia

Answer 13

more dopamine. in Brocas area this causes auditory hallucinations and speech poverty

Question 14

hypodopaminergia

Answer 14

less dopamine. in frontal cortex, causes avolition and speech poverty

Question 15

updated dopamine hypothesis

Answer 15

hypodopaminergia in the pre-frontal cortex leads to negative symptoms like apathy and avolition

Question 16

support for the dopamine hypothesis

Answer 16

dopamine antagonists used which blocked dopamine pathways and was linked to a reduction in positive symptoms

Question 17

strengths of the biological explanations of schizophrenia

Answer 17

+ strong evidence base (e.g Gottesman and Tienari), suggests that some people are more vulnerable due to genes
+ application of genetic counselling -> help identify families at risk and keep an eye
+ support for idea that dopamine is involved in schizophrenia from Curran et al (increased DL worsens symptoms and can induce) and Trascher et al (reduced DL reduces intensity of symptoms)

Question 18

limitations of the biological explanation of schizophrenia

Answer 18

• neural correlates do not show causation, does the activation levels cause the symptoms or do the symptoms cause the low activation levels?
• high glutamine levels in brains of patients with schizophrenia, does glutamine cause and not dopamine?
• reductionist approach
• environmental factors like childhood trauma, drugs, birth complications, etc. can play role. 67% with schizophrenia claimed to have one instance of childhood trauma, only 38% without schizophrenia and MZ twins don’t have 100% CR.

Question 19

what area of the brain are positive symptoms associated with (neural correlates)

Answer 19

lowered activity in the superior temporal gyrus and anterior cingulate gyrus

Question 20

what area of the brain are negative symptoms associated with (neural correlates)

Answer 20

lowered activity in the ventral striatum