the biological explanation of schizophrenia

Question 1

which family study is a good example?

Answer 1

Gottesman and Shields (1991)

Question 2

what was Gottesman and Shield’s study?

Answer 2

•conducted a twin study
•looked at twins of which one had developed schizophrenia
•used 56 pairs of twins
•concordance rates
DZ twins: 17%
MZ twins: 48%
•shows that there must be a strong genetic basis, due to the general incidence rates being 1%
•the closer the genetic relatedness, the higher the risk

Question 3

what role do candidate genes play in schizophrenia?

Answer 3

•schizophrenia is believed to be polygenic (the result of a number of different genes)
•the most likely genes would be those coding for neurotransmitters including dopamine
•schizophrenia is aetiologically heterogenous (combinations of different factors can lead to the condition)

Question 4

three limitations of Gottesman and Shields study

Answer 4

• because the concordance rate is not 100%, it implies it is not entirely down to genes and that environmental factors are involved
• cannot be sure if they were DZ or MZ twins, as genetic testing was not advanced enough so there was no scientific way of seeing what type of twins they were
• the original study was in 1972, this predates the DSM and the ICD, therefore how to we know the twins actually had schizophrenia? they may have been misdiagnosed as the schizophrenia is co-morbid with other illnesses (depression 50%). therefore the validity is questioned

Question 5

who conducted an adoption study?

Answer 5

The Copenhagen high-risk study (Kety 1962)

Question 6

what was the Copenhagen high-risk study (Kety 1962)

Answer 6

•Kety identified 207 offspring of mothers diagnosed with schizophrenia (high-risk) along with a matched control of 104 children with ‘healthy’ mothers (low-risk) in 1962
•the children were aged between 10-18 years at the start of the study
•used a matched pairs design. they were matched on:
- age, socioeconomic status, gender of babies, urban/ rural
•schizophrenia was diagnosed in 16.2% of the high-risk group compared to 1.9% of the low-risk group

Question 7

limitations of Kety’s study

Answer 7

• pre-dates the diagnostic tools, so it’s unsure whether the kids/ moth had schizophrenia as it was assessed using different criteria, none of which was standardised
• no control over the age of adoptees (so they could have been adopted at 1 or 9 years old), so their risk would have increased with the longer they were in a high risk environment

Question 8

what percentage of people have depression / substance abuse and schizophrenia?

Answer 8

50% depression
49% substance abuse

Question 9

what percentage of caring responsibilities still fall down to women?

Answer 9

84%

Question 10

results of the twin study:

Answer 10

DZ: 17%
MZ: 48%