biological therapy- drug therapy

Question 1

drug therapies

Answer 1

most common treatment antipsychotic drugs
may be required in short-term or long-term
typical (traditional) and atypical (newer second-generation)

Question 2

typical antipsychotics

Answer 2

around since 1950s. e.g. chlorpromazine

Question 3

how do typical antipsychotics work?

dopamine antagonists

Answer 3

chlorpromazine acts as an antagonist in dopamine system. blocks dopamine receptors at postsynaptic neuron. initially causes dopamine levels to build up but over time reduces the production and action of dopamine.

dopamine hypothesis- dopamine antagonist effect normalises neurotransmission in key areas of the brain, reducing symptoms like hallucinations.

Question 4

how do typical antipsychotics work?

sedation effect

Answer 4

chlorpromazine also an effective sedative, perhaps due to effect on histamine receptors.
calms hospital patients (not just with schiz) when very anxious, in syrup form as absorbed faster

Question 5

atypical antipsychotics

Answer 5

around since 1970s.
aim to increase effectiveness and reduce side-effects of typical antipsychotics.
e.g. clozapine. initially withdrawn in 1970s after some patients died from angranulocytosis (blood condition). reintroduced in 1980s after found to be more effective than typical drugs. effective as last resort with regular blood tests.

Question 6

how do atypical antipsychotics work?

clozapine

Answer 6

clozapine binds to dopamine receptors, but also acts on serotonin and glutamate receptors. therefore reduces depression and anxiety in patients, and may also improve cognitive functioning.

often prescribed to highly suicidal- mood-enhancing effect. important as 30-50% of schiz attempt suicide at one point.

Question 7

how do atypical antipsychotics work?

risperidone

Answer 7

developed in 1990s to be as effective as clozapine without side-effects
binds more strongly than clozapine to dopamine and serotonin receptors. lowers required dose so may reduce side-effects.

Question 8

strength

evidence for effectiveness

Answer 8

thornley (2003)- reviewed studies comparing effects of chlorpromazine to control conditions
data from 13 trials, 1121 participants- chlor better overall functioning and reduced symptom severity than placebo
meltzer (2012)- clozapine more effective than typical APs and other atypical APs. effective in 30-50% of treatment-resistant cases where typical APs have failed.

Question 9

limitation

side effects

Answer 9

typical- diziness, agitation, sleepiness, stiff jaw, weight gain and itchy skin. LT use- tardive dyskinesia (caused by dopamine supersensitivity. involuntary face movements)

most serious of APs (particularly typical APs)- neuroleptic malignant syndrome (NMS). drug blocks dopamine action in hypothalamus. high temperature, delirium and coma, can be fatal.

can do harm as well as good. treatment ineffective as many may avoid it.

Question 10

limitation

mechanism unclear

Answer 10

understanding of how APs work linked to original dopamine hypothesis (symptoms of schiz linked to high lvls of dopamine activity in subcortex of brain). but incomplete expl- other parts of brain dopamine lvls too low. if this true then most APs shouldn’t work.

at least for some APs may be ineffective. or, some other factor involved in their mechanism making them effective.