Biological explanations for schizophrenia: Flashcards

genetics and neural correlates, including the dopamine hypothesis.

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1
Q

explain the genetic explanation for schizophrenia

A

suggests that schizophrenia is inherited
polygenetic disorder - multiple genes are associated with a higher risk of developing schizophrenia
high concordance rates in closely related families

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2
Q

research evidence for genetic explanation of schizophrenia - twin studies

A

Gottesman (1991) reviewed cases of schizophrenia in twins
found concordance rate of 48% in MZ twins, 17% in DZ twins compared to 1% in general population
MZ and DZ twins usually share similar environment so result suggest schizophrenia has a genetic aspect but not fully genetic

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3
Q

research evidence for genetic explanation of schizophrenia - family studies

A

Gottesman (1991) reviewed cases of schizophrenia in families
found that children with 2 schizophrenic parents had a concordance rate of 48% and those which 1 schizophrenic parent was 13% and those with siblings with SZ was 9%

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4
Q

research evidence for genetic explanation of schizophrenia - adoption studies

A

Tienari (2004) studied the biological children of schizophrenic mothers who had been adopted
found that 5.8% of children adopted into psychologically healthy families development schizophrenia compared to 36.85 that were raised in dysfunctional families
as the risk is above the general population (1%) this suggests a genetic basis but an argument could be made for psychological factors too

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5
Q

what are neural correlates?

A

patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience

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6
Q

explain the neural explanation for schizophrenia

A

The dopamine hypothesis suggests that symptoms of schizophrenia are associated with an imbalance of the neurotransmitter dopamine in the brain
hyperdopaminergia - too much dopamine in Broca’s area - may lead to auditory hallucinations (positive symptoms)
hypodopaminergia - too little dopamine in frontal cortex - may lead to avolition or speech poverty (negative symptoms)

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7
Q

how did the dopamine hypothesis come about?

A

from observations that found dopamine releasing drugs e.g. L-dopa can produce schizophrenic-like symptoms in healthy patients and anti-psychotic drugs e.g. phenothiazine decrease symptoms of SZ and reduce dopamine levels

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8
Q

what are other neurotransmitters that may explain SZ?

A

glutamate - excitatory neurotransmitter - involved in learning, attention and memory - low levels in people with SZ
serotonin - found to effect SZ - led to development of treatments like clozapine

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9
Q

research evidence for neural correlates - the dopamine hypothesis

A

Patel et al (2010) used PET scans and found lower dopamine levels in prefrontal cortex of people with SZ compared to ‘normal’ controls

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10
Q

evaluations of genetic explanations of SZ

A

+ strong evidence for genetic vulnerability to SZ - Gottesman (family and twins) and Tienari (adoption studies) - suggests genetic factors make people more vulnerable
- biological reductionist - evidence to show environmental factors increase risk of developing SZ - e.g. birth complications, smoking THC-rich cannabis, childhood trauma - study found 67% of people with SZ reported childhood trauma compared to 38% in non-psychotic group - genetic factor is not the only factor
+- suggests a diathesis-stress model can explain SZ - holistic

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11
Q

evaluations of neural explanations of SZ

A

+ evidence from drug studies supporting abnormal dopamine functioning - dopamine agonists e.g. amphetamines increase dopamine levels making SZ worse or producing SZ-like symptoms in people without SZ and antipsychotic drugs reduce dopamine activity and are used as an effective treatment for people with SZ - suggests dopamine is involved in symptoms of SZ
- evidence for a central role of glutamate - post-mortem and live-scanning studies found raised levels of glutamate in brains of people with SZ - several candidate genes are believed to be involved in glutamate production - dopamine is not the other neurotransmitter affecting SZ

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