biological explanations for schizophrenia

Question 1

concordance rate

Answer 1

refers to the extent to which a pair of twins share similar characteristics/traits

Question 2

gottesman (1991)- meta anaylsis of family studies
- Procedure

Answer 2

12 studies, across 8 countries, ranging over 60 years with approx 2000 pairs of twins

Question 3

gottesman (1991)
- Findings

Answer 3

• if a parent suffers from schizophrenia, there there’s a 6% of developing it (compared to 1% of general population)
• concordance rates for schizophrenia was 48% for MZ twins compared to 17% in DZ twins

Question 4

gottesman (1991)
- Conclusions

Answer 4

• genetics play a significant role in explaining schizophrenia
• however, as MZ concordance rates are not 100%, there are clearly environmental factors as well

Question 5

strengths of gottesman

Answer 5

• the meta-analysis is large-scale and longitudinal, both contributing to validity
• many other studies shown a genetic link e.g Tienari et al (2004), Ripke (2014)

Question 6

weaknesses of gottesman

Answer 6

• higher concordance rate between MZ twins could be explained by greater environmental similarity rather than genetic similarity,,, MZ twins elicit more similar treatment than DZ twins,,, always an issue with twin studies
• studies in gottesman’s meta-analysis were from 1920s onwards, and had wide range of different methods for measuring twins and schizophrenia - questions both reliability and validity

Question 7

candidate genes

Answer 7

genes that have been implicated in the development of schizophrenia

Question 8

polygenic

Answer 8

schizophrenia is thought to be polygenic - its development is not determined by a single gene but a few (maybe as many as 108)

Question 9

aetiologically heterogeneous

Answer 9

schizophrenia can be caused by a different combination of genes

Question 10

the dopamine hypothesis

Answer 10

an imbalance or disregulation of dopamine has been implicated in the development of schizophrenia

Question 11

hyperdopaminergia

Answer 11

• excess levels of dopamine in the subcortex (central area of brain)
• e,g brocas area
• associated with disorganised speech and auditory hallucinations (positive symptoms)

Question 12

hypodopaminergia

Answer 12

• low levels of dopamine in prefrontal cortex
• resulting in negative symptoms e.g avoliton

Question 13

evidence: amphetamines and cocaine

Answer 13

• dopamine agonists (increase)
• large doses of these drugs cause hallucinations and delusions in non-schizophrenics and make schizophrenics worse

Question 14

antipsychotic drugs

Answer 14

• dopamine anatgonists (reduce)
• eliminate hallucinations and delusions
• by alleviating many of the symptoms of schizoprenia, antipsychotic drugs strengthen the case for dopamine being a significant contributory factor

Question 15

evaluation of dopamine hypothesis

Answer 15

• post mortems have revealed higher than normal levels of D2 dopamine receptors in the brain of schizophrenics
• PET scans of schizophrenics have found similar results
• dopamine hypothesis is simplistic as there are many more neurotransmitters involved - such as glutamate

Question 16

neural correlates

Answer 16

refers to finding areas or circuits of the brain that are related to a specific behaviour or condition

Question 17

neural correlates of negative symptoms

Answer 17

• lower levels of activity in the ventral striatum has been linked to the development of avoliton
• ventral striatum: involved in the anticipation of a reward for certain actions
• therefore, if there is abnormality in areas, such as the ventral striatum, then this would result in a lack of motivation (avolition)

Question 18

neural correlates of positive symptoms

Answer 18

reduced activity in the superior temporal gyrus and anterior cingulate gyrus have been linked to the development of auditory hallucinations

Question 19

evaluation summary

Answer 19

• there is no conclusive explanation that account for all schizophrenics- research is difficult to interpret and there have been contradictory findings
• difficult to establish cause and effect- as many participant studies have suffered from schizophrenia for a while and have been undergoing treatment
• biological explanations are reductionist in attempting to explain a complex multi-faceted disorder at the level of cells, genes, and chemicals - diathesis stress model