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%

Question 11

what is one of the hypothesis’ in the biological explanation?

Answer 11

the dopamine hypothesis

Question 12

what is dopamine related to?

Answer 12

reward, motivation and movement

Question 13

what type of neurotransmitter is dopamine?

Answer 13

excitatory

Question 14

what are the two things in the dopamine hypothesis that could relate to schizophrenia?

Answer 14

•too much dopamine will lead to perception without sensation (hallucinations)
•hyper sensitive receptor sites

Question 15

what does a lack of dopamine cause?

Answer 15

parkinson’s disease. L-dopa is a synthetic dopamine, given to people to restore dopamine levels. taking too much can lead to schizophrenic like symptoms.

Question 16

3 drugs related to proving the dopamine hypothesis:

Answer 16

• LSD/ Amphetamines
• Anti-psychotics
• L-Dopa

Question 17

LSD/ Amphetamines showing dopamine association

Answer 17

•LSD and Amphetamines work by flooding the synapse with dopamine and making the dopamine receptors hyper-sensitive, resulting in schizophrenia-like positive symptoms . Therefore dopamine is associated with schizophrenia.

Question 18

Anti-psychotics showing association between dopamine and schizophrenia

Answer 18

Antipsychotics work by blocking the dopamine receptors by binding to the receptor site, reducing the symptoms of schizophrenia. therefore dopamine is associated with schizophrenia.

Question 19

L-Dopa showing dopamine association

Answer 19

L-Dopa was a drug manufactured in the 1950s to control parkinson’s disease. it is an artificial dopamine and functions like dopamine. if you take too high a dose it can produce schizophrenia-like symptoms. therefore dopamine is associated with schizophrenia.

Question 20

two limitations of the dopamine hypothesis

Answer 20

• it is reductionist, reducing behaviour down to a single neurotransmitter. schizophrenia is complex and cannot be explained by one component.
• correlation does not equal causation, we cannot establish cause and effect.

Question 21

what are neural correlates?

Answer 21

structural brain abnormalities correlated with symptoms

Question 22

what are the three parts of the brain associated with schizophrenia?

Answer 22

• ventral striatum
• gyrus
•enlarged ventricles

Question 23

what is the ventral striatum and how does it effect schizophrenia?

Answer 23

•an abnormality in this area may be involved in the development of avolition (the loss of effect)
•they observed a negative correlation between activity levels in this area and the severity of overall negative symptoms
•the area is involved in motivation and reward, as well as anticipation

Question 24

what is the gyrus and how is it related to schizophrenia?

Answer 24

•lower activation levels in the gyrus were found in participants with hallucinations (specifically auditory hallucinations)
•associated with the auditory areas of the brain
•Allen did an fMRI scan and found the lower activity levels
•recorded conversations with them and found that the more serious the auditory hallucinations the more mistakes they made identifying their own voice in a recording

Question 25

what type of correlation is there between activity levels in the gyrus and auditory hallucinations?

Answer 25

negative correlation

Question 26

what are enlarged ventricles and how to they relate to schizophrenia?

Answer 26

•researchers have found that many schizophrenics have enlarged ventricles, these are cavities in the brain that supply nutrients and remove waste •Torrey (2002) found that the ventricles tend to display negative rather than positive humorous and have greater cognitive disturbances and a poorer response to traditional antipsychotics •there is a positive correlation •the lack of grey matter is what influences the symptoms

Question 27

What did Torrey find and what is a limitation of it?

Answer 27

Torrey found that the ventricles of a schizophrenic are 15% bigger on average than normal, yet this correlation was only found in male patients. this means his results may be subject to gender bias.

Question 28

enlarged ventricles limitation

Answer 28

- correlation does not equal causation, we do not know whether the lack of grey matter caused schizophrenia or whether it was the other way round

Question 29

a limitation of the biological explanation: environmental factors

Answer 29

•there is evidence to show that environmental factors also increase the risk of developing schizophrenia •childhood trauma leave people more vulnerable to mental health problems •A study found that people with schizophrenia and related psychotic disorders reported at least one childhood trauma as opposed to 38% of a matched group with non-psychotic mental health issues •this means genetic factors alone cannot provide a complete explanation of schizophrenia

Question 30

what is a strength of the biological explanation?

Answer 30

genetic counselling if one or more potential parents have a relative with schizophrenia they risk having a child who would go on to develop the condition however this risk is just an estimate as they will go on to experience a particular environment which also has risk factors