Biological explanations of schizophrenia

Question 1

Is schizophrenia genetic

Answer 1

YES
-suggested by Gottesman’s 1991 large-scale family study
(may also suggest environmental cause often share environments)

Question 2

What percentage does someone have of developing schizophrenia if their aunt has it (Gottesman)

Answer 2

2%

Question 3

What percentage does someone have of developing schizophrenia if their sibling has it (Gottesman)

Answer 3

9%

Question 4

What percentage does someone have of developing schizophrenia if their MZ twin has it (Gottesman)

Answer 4

48%

Question 5

What does aetiologically heterogenous mean

Answer 5

Condition caused by combination of factors (e.g genetic/environmental)

Question 6

Is schizophrenia polygenic

Answer 6

YES

Question 7

Which genes are most likely to cause schizophrenia

Answer 7

Those coding for neurotransmitters like dopamine

Question 8

What did Ripke find?

Answer 8

Meta-analysis of genome-wide studies= 108 genetic variations associated with risk

BUT other studies found different candidate genes/aetiologically heterogenous

Question 9

What is the role of mutation in schizophrenia

Answer 9

+ paternal age can= sperm mutation
Risk of schizophrenia 0.7% with >25 fathers but 2% with <50

Question 10

Original dopamine hypothesis

Answer 10

Antipsychotics used for schizophrenia - dopamine so schizophrenia caused by + dopamine in subcortical areas in brain

Question 11

Example of hyperdopaminergia causing symptoms of schizophrenia

Answer 11

Excess of DA receptors in pathways from subcortex to Broca’s area (speech production)= speech poverty

Question 12

Updated version of dopamine hypothesis

Answer 12

Davis et al: Also caused by low DA
-Low DA causes high DA so includes both explanations

Explains origins: Both genetics/experiences of stress create vulnerability

Question 13

Example of low DA causing schizophrenia symptoms

Answer 13

Low DA in prefrontal cortex (responsible for thinking) could explain cognitive problems- negative symptoms

Question 14

Strength of genetic explanation for schizophrenia

Answer 14

Strong evidence base
-e.g family studies like Gottesman
-Pekka Tienari adoption studies
-Rikke Hilker twin studies

Question 15

Weakness of genetic explanation for schizophrenia

Answer 15

Evidence for environmental factors
-Biological= birth complications/weed teens
-Psychological= childhood trauma (e.g Nina Morkved)

Suggests genetics not complete explanation

Question 16

Rikke Hilker schizophrenic twin studies

Answer 16

Found concordance rates 33% for MZ/7% for DZ
-Suggests genetic explanation

Question 17

Nina Morkved schizophrenia trauma studies

Answer 17

Found 67% of schizophrenics in sample had experienced childhood trauma
-Suggests environmental explanation

Question 18

Strength of dopamine causing schizophrenia

Answer 18

Strong evidence
-e.g amphetamines + DA and worsen symptoms/can induce in non-schizophrenics

-Antipsychotic drugs - DA/symptoms

-Some candidate genes produce DA/receptors of

Question 19

Weakness of dopamine causing schizophrenia

Answer 19

Post-mortem/live scanning studies found + levels of neurotransmitter glutamine/some candidate genes involved in its production/processing

-So not just dopamine involved