SZ: Neurotransmitters as an explanation

Question 1

what is the dopamine hypothesis?

Answer 1

suggests unusual behaviour associated with disorder can be explained by dopamine function in brain

Question 2

excess dopamine- hyperdopaminergia

what 2 drugs were found to alleviate symptoms of SZ?

Answer 2

chlorprozamine
resperine
BUT, induced tremors and muscle rigidity - Parkinsons disease caused by low levels of dopamine
SO, argued schizophrenic symptoms may be linked to dopamine

Question 3

what were the causes of excess levels?

Answer 3

1. low levels of beta hydroxylase - enzyme that breaks down dopamine may be responsible for high levels in synapse
2. proliferation of D2 dopamine receptors may be responsible for hyperdopaminergic activity

Question 4

dopamine deficiency- hypodopaminergia

expain?

Answer 4

Davis suggested positive symptoms of SZ > excess dopaminergic activity in mesolimbic pathway
negative symptoms > lack of dopaminergic activity in mesocortical pathway

Question 5

serotonin and negative symptoms

what neurotransmitters began to be more focused on by the 2000’s?

Answer 5

glutamate
serotonin
GABA

Question 6

what was the new drug introduced and what does it do?

Answer 6

antipsychotic- clozapine
binds D1 and D4 dopamine receptors, only to weaken D2 receptors
Because clozapine binds serotonin receptors and reduces p and n symptoms - argued irregular serotonergic activity causes n symptoms

Question 7

dopamine dysregulation

Answer 7

dopamine dysregulation in the striatum as the common pathway to psychosis.

Question 8

what did they focus on and believe?

Answer 8

interactions between genetic, environmental and social factors and believe dopamine hypothesis should be viewed as explanation of psychosis proneness, not explanation of SZ

Question 9

strengths? research or studies?

Answer 9

-rats treated with amphetamines
>Tenn found rats given 9 amphetamine injections portrayed schizophrenic symptoms over 3 weeks
>dopamine antagonists were successful in reversing the effects
SO, increased dopamine levels may be cause of SZ

Question 10

BUT…?

Answer 10

others found a dopamine agonist which stimulated D2 receptors does not induce psychotic symptoms
SO, challenges idea hyperdopaminergia causes p symptoms

Question 11

weakness?

Answer 11

-can’t explain why certain groups like 2nd gen immIgrants, are more likely to be diagnosed with SZ
EG. Veiling showed Moroccan immigrants more likely diagnosed with SZ than Turkish immigrants
>correlated with amount if discrimination faced by each group
SUGGESTS, environmental factors like stress may make people more prone to psychosis

Question 12

strength?

Answer 12

-support for role of D2 receptors

EG. Snyder found chlorpromazine acts as antagonist and has antipsychotic effects (haloperidol)

Question 13

application?

Answer 13

-drug treatments
dopamine antagonists that bind to D2 receptors can reduce p symptoms
atypical drugs like clozapine which blocks serotonin receptors have been successful in reducing p and n symptoms
SO, people with SZ can live without being in residential care > symptoms controlled