Biological therapy Flashcards
(18 cards)
What is drug therapy within schizophrenia?
Common treatment involves use of antipsychotic drugs
What are antipsychotic drugs?
A person with psychosis experiences some loss of contact with reality
Defining characteristic of schizophrenia and related disorders
How are antipsychotics used?
Short or long term
Short term - Take it and then stop their use without the return of symptoms
For life - or face likelihood of returning symptoms
What are typical anitpsychotics?
Chloropromazine
Around since 1950s
What is chlorpromazine?
Taken as tablets, syrup, injection
Orally - daily up to maximum of 1000 mg
Initial doses much smaller and dosage normally increase to maximum of 400-800mg
Prescribed doses have decline over the last 50 years
What are dopamine antagonists?
Strong association between use of typical antipsychotics and dopamine hypothesis
How do typical antipsychotics work?
Antagonists in the dopamine system
Antagonists - chemicals which reduce action of neurotransmitter
How do dopamine antagonists work?
Blocking dopamine receptors in synapses of the brain
Reducing action of dopamine
Initially when individual takes chlorpromazine - dopamine levels build up but then production is reduced
Dopamine hypothesis - dopamine antagonist effect normalises neurotransmission in key areas of the brain - reducing symptoms like hallucinations
What is a property of chlorpromazine?
Sedation effect
Related to effect on histamine receptors
Not fully understood
Used to calm down individuals
Often done when patients are first admitted to hospitals and are very anxious
Syrup
Absorbed faster than tablets so tends to be given when used for sedative properties
What are atypical antipsychotics?
Used since 1970s
Developing newer antipsychotics - maintain or improve upon effectiveness of drugs in suppressing the symptoms of psychosis and also minimise side effect of drugs used
What is Clozapine?
More effective than typical
Used when other treatments failed
Regular blood tests when taking drug to ensure they don’t have agranulocytosis
Potentially fatal side effects
Not available as injection
Drug dosage - little lower than chlorpromazine, 300-450mg a day
How does clozapine work?
Binds to dopamine receptors
Acts in serotonin and glutamate receptors
Action helps to improve mood and reduce depression and anxiety
Improve cognitive functioning
Sometimes prescribed when individual considered at high risk of suicide
30 to 50% of people with schiz attempt suicide at some point
What is risperidone?
Attempt to produce a drug as effective as clozapine without serious side effects
Taken in forms of tablet, syrup or injection that lasts for around 2 weeks
Small dosage is initially given
This is built up to typical daily dose of 4-8mg and max of 12 mg
How does risperidone work?
Bind to dopamine and seretonin receptors
Binds more strongly to dopamine receptors than clozapine
Effective in much smaller doses than most antipsychotics
Some evidence suggest that this leads to fewer side effects than other antipsychotics
What is a strength of antipsychotics?
Evidence for effectiveness
Thornley et al
Reviewed studies comparing the effects of chlorpromazine to control conditions
Data from 13 trails with a total of 1121 participants
Chlorpromazine was associated with better overall functioning and reduced symptom severity as compared to placebo
Meltzer
Clozapine is more effective than typical antipsychotics and other atypical antipsychotics
Effective in 30-50% of treatment-resistant cases where typical have failed
Meaning that as far as we can tell antipsychotics work
What is a counter point to evidence of effectiveness?
Healy
Serious flaws with evidence for effectiveness
Most studies of short term effects
Some successful trails have had their data published multiple times - exaggerating size of evidence base for positive effects
Antipsychotics - powerful calming effects - easy to demonstrate that they have positive effects on people
Not the same as saying they really reduce severity of psychosis
Meaning evidence base for antipsychotics effectiveness is less impressive than it first appears
What is a limitation of antipsychotic drugs?
Likelihood of side effects
Typical antipsychotics - dizziness, agitation, sleepiness, stiff jaw, weight gain, itchy skin
Long term - tardive dyskinesia - caused by dopamine supersensitivity and causes involuntary facial movemements such as grimacing, blinking and lip smacking
Neuroleptic malignant syndrome - causes when drug blocks dopamine action in hypothalamus
Area in brain associated with regulation of a number of body systems
Result in high temperature, delirium and coma
Estimate its frequency range from less than 0/1% to just over 2%
Meaning atipsychotics can do harm as well as good
Individuals who experience these may avoid such treatments
What is a further limitation of antipsychotics?
We dont know why they work
Original dopamine hypothesis is not complete explanation for schiz
Dopamine levels is other parts of brain are too low rather than too high
If this is true most antipsychotics would not work
Questions over the effectiveness adds to argument that in fact they are ineffective
At least some of antipsychotics may not be the best treatment to opt for
Perhaps some other factor involved in their apparent success
