Biological Explanations of Schizophrenia

Question 1

what are the subs of the genetic basis of schizophrenia?

Answer 1

• family studies
• candidate genes
• the role of mutation

Question 2

what is the role of family studies in schizophrenia?

Answer 2

• family studies have confirmed that risk of schizophrenia increases in line with genetic similarities to a relative with the disorder

Question 3

who is the researcher involved in the family studies of schizophrenia?

Answer 3

• Gottesman

Question 4

what did Gottesman do?

Answer 4

• large-scale family study
• e.g. someone with an aunt with schizophrenia has a 2% chance of developing it, increasing to 9% if the individual is a sibling and 48% if they are an identical twin

Question 5

how do candidate genes link to schizophrenia?

Answer 5

• early research = belief that one faulty gene could explain schizophrenia
• a different number of genes are involved
• schizophrenia is polygenic
• the most likely genes would be those coding for neurotransmitters including dopamine

Question 6

who is the researcher involved in candidate genes?

Answer 6

Ripke et al

Question 7

what did Ripke et al do?

Answer 7

• combined all previous data from genome-wide studies of schizophrenia
• genetic make-up of 37,000 people with a diagnosis of schizophrenia was compared to that of 113,000 controls, 108 separate genetic variations were associated with slightly increased risk of schizophrenia
• different studies have identified different candidate genes it also appear that schizophrenia is aetiologically heterogenous

Question 8

what does etiologically heterogeneous mean?

Answer 8

• different combinations of factors can lead to the condition

Question 9

explain the role of mutation in schizophrenia?

Answer 9

• schizophrenia can also have a genetic origin in the absence of family history of the disorder
• this may be because of a mutation in parental DNA which can be caused by radiation, poison or viral infection

Question 10

who is the researcher involved in the role of mutations in schizophrenia?

Answer 10

• Brown et al

Question 11

what did Brown et al do?

Answer 11

• evidence for mutation comes from positive correlations between paternal age and risk of schizophrenia, increasing from 0.7% with fathers under 25 to over 2% in after over 50

Question 12

what is paternal age associated with in the role of mutation?

Answer 12

• associated with increased risk of sperm mutation

Question 13

what is the neural correlates of schizophrenia?

Answer 13

• dopamine hypothesis

Question 14

what is the original dopamine hypothesis?

Answer 14

• original hypothesis was based not he discovery that drugs used to treat schizophrenia caused symptoms similar to those in people with Parkinson’s disease (condition associated with low DA levels = Seeman)
• schizophrenia might be the result of high levels of FA in subcortical areas of the brain

Question 15

what is an example of a drug used to treat schizophrenia?

Answer 15

• antipsychotics which reduces dopamine (DA)

Question 16

what is an example of high levels of DA?

Answer 16

• an excess of DA receptors in pathways from the sub cortex to the Broca’s area may explain specific symptoms of schizophrenia such as poverty of speech and or auditory hallucinations

Question 17

what is is called when there is high levels of dopamine?

Answer 17

• hyperdopaminergia

Question 18

who are the researchers involved in updated version of the dopamine hypothesis

Answer 18

Davis et al

Question 19

what did David et al do?

Answer 19

• proposed the addition of cortical hypodopaminergia = abnormally low DA in the brain’s cortex, which can explain the symptoms of schizophrenia
• e.g. low DA in the prefrontal cortex could explain cognitive problems
• cortical hypodopaminergia leads to subcortical hyperdopaminergia, so both high and low levels of DA in different brain regions are part of the updated version

Question 20

what did Howes et al say about the updated versions of dopamine hypothesis?

Answer 20

• both genetic variations and early experiences of stress, both psychological and physical, make some people more sensitive to cortical hypodopaminergia and hence subcortical hyperdopaminergia

Question 21

what is the best known neural correlate of schizophrenia?

Answer 21

dopamine

Question 22

what are the evaluations for the genetic basis of schizophrenia?

Answer 22

+ strong evidence base
- there is clear evidence to show that environmental factors also increase the risk of schizophrenia

Question 23

what are the evaluations for the neural correlates of schizophrenia?

Answer 23

+ there is support for the idea that dopamine is involved in schizophrenia
- there is evidence for the central role of glutamate