biological theory for schizophrenia Flashcards
what is drug therapy
antipsychotic drugs
person with psychosis experiences loss of contact with reality, defining characteristic of schizophrenia
may be required short or long term
some people can take short course then stop their use without return of symptoms
others require for longterm or face likelihood of recurrence of schizophrenia
can be dividided in typical and atypical or second generation drugs
what is typical antipsychotics
include chlorpromazine- taken as tablets syrup or injection
taken orally, administered daily up to max of 1000mg, intially doses much smaller and dosage gradually increase to max of 400/800mg
typical prescribed doses declined over last 50yrs
dopamine antagonists- strong association between use of typical antipsychotics and dopamine hypothesis, work by acting as antagonists in dopamine system, chemicas which reduce the action of neurotransmitter, work by blocking dopamine receptors in synapses of brain reducing the action of dopamine, antagonist effect normalises neurotransmission in key areas of brain reducing symtpoms
sedation effect- chlorpromazine effective sedative, believed to be related to effec on histimane receptors but not fully understood how leads to sedation, used to calm individuals, often done when patients first admitted to hospitals and are very anxious, syrup absorbed faster than tablets so tends to be given when used to sedative properties
what are atypical antipsychotics
aim in developing newer antipsychotics maintain or improve upon effectiveness of drugs in suppressing the symptoms of psychosis and minimise side effects of drug used
clozapine- treatment for schizophrenia to be used when others failed, people taking it have regular blood checks to ensure they are not developing agranulocytosis, potentially fatal side effects, not available as injection, daily dosage lower up to 300-450mg per day, binds dopamine receptors but acts on serotonin and glutamate receptors, action helps improve mood and reduce depression and anxiety in patients, improve cognitive functioning, mood enhancing effects prescribed when considered high risk suicide, important as 30-50% of poeple woth schizoporehnia attempt suicide at one point
risperidone- attempt to produce effective drug as clozapine but without serious side effects, can be taken in form of tablets syrup and injection that lasts 2weeks, small dose given and built up to typical daily dose of 4-8mg and max of 12mg, believed to bind dopamine and serotonin receptors, binds more strongly to dopamine receptors and effective in smaller doses, evidence to suggest this leads to fewer side effects than others
what is evidence for effectiveness (evaluation)
evidence to support effectiveness
large body of evidence support idea both typical and atypical at least moderately effective in tackling symptoms of schizophrenia
thornley-reviewed studies comparing effects of chlorpromazine to control conditions, data from 13trials with total of 1121pps showed that it was associated with better overall functioning and reduced symptom servity as compared to placebo,
evidence for benefits of atypical antipsychotics
meltzer-concluded clozapine more effective than typical antipsychotics and other atypical antipsychotics and effective in 30-50% treatment resistant cases where typical antipsychotics failed
antipsychotics work
healy- suggested serious flaws with evidence for effectiveness
most studies are of short term effects only and some successful trials have had their data published multiple times exaggerating size of evidence base for positive effects
antipsychotics powerful calming effects easy to demonstrate they have some positive effect on people experiencing symptoms of schizophrenia
not the same as saying they really reduce severity of psychosis
evidence base for antipsychotic effectiveness is less impressive than first appears
what are serious side effects (evaluation)
likelihood of serious side effects
typical-associatwed with range of side effects including dizziness agitation sleepiness etc
long term use can result in tardive dyskinesia caused by dopamine supersensitivity and causes involuntary facial movements
most serious- neuoleptic malignant syndrome- caused hen drug blocks dopamine action in hypothalamus (associated with regulation of number of body symptoms) reuslts in high temp delirium and coma, can be fatal
estimates of frequency range from less thna 0.1% to just over 2%
can do harm as well as good and invididuals who experience these may avoid treatments
what is mechanism unclear (evaluation)
dont know why they work
which antipsychotic drug work is strongly tied up with original dopamine hypothesis
original dopamine hypothesis not complete explanation for schizophrenia- if true then msot shouldnt work
questions over effectiveness of antipsychotics anyways adds to argument that they are ineffective
may not be best treatment to opt for- some other factor involved in apparent success
