biological therapy for schizophrenia

    Cards (13)

    • Typical antipsychotics: dopamine antagonists:
      • typical antipsychotic drugs (e.g. chlopromazine) have been around since the 1950s.
      • they aim to work by acting as antagonists in the dopamine system and aim to reduce the action of dopamine - they are strongly associated with the dopamine hypothesis
    • Typical antipsychotics: block dopamine receptors in synapses
      • dopamine antagonists work by blocking dopamine receptors in synapses in the brain, reducing the action of dopamine
      • initially, dopamine levels build up after taking chlopromazine, but then production is reduced
      • this normalizes neurotransmission in key areas of the brain, which turn reduces symptoms like hallucinations
    • Typical antipsychotics: Chorpromazine side effect
      • chlorpromazine also has an effect on histamine receptors which appears to lead to a sedation effect
      • it is also used generally to calm anxious patients when they are first admitted to the hospital
    • Typical antipsychotics: chlorpromazine
      • taken in form of tablets, syrup or injection
      • dosage: max of 1000mg a day but typically 400-800mg
    • Atypical antipsychotics:
      • the aim of developing newer antipsychotics was to maintain or improve upon the effectiveness of drugs in suppressing the symptoms of psychosis and also to minimize side effects of the drugs used
    • Atypical antipsychotics: clozapine
      • clozapine binds to dopamine receptors as chlorpromazine does, but it also acts on serotonin and glutamate receptors
      • this drug was more effective than typical antipsychotics - clozapine reduces depression and anxiety as well as improving cognitive functioning
      • it also improves mood, which is important as up to 50% of people with sz attempt suicide
    • Atypical antipsychotics: risperidone
      • risperidone was developed in the 1990s because clozapine was involved in the deaths of some people from a blood condition called agranulocytosis
      • risperidone, like clozapine binds to dopamine and serotonin receptors
      • but risperidone binds more strongly to dopamine receptors and is therefore more effective in smaller doses than most antipsychotics and has fewer side effects
    • One strength of antipsychotics is evidence of their effectiveness. Thornley et al. (2003) reviewed data from 13 trials (1121 ppts) and found that chlopromazine was associated with better functioning and reduced symptom severity compared with a placebo. There is also support for the benefits of atypical antipsychotics. Meltzer (2012) concluded that clozapine is more effective than typical antipsychotics, and that it is effective in 30-50% of treatment-resistant cases. This means that as far as we can tell, antipsychotics work.
    • Counterpoint for evidence of antipsychotics effectiveness
      However, most studies are of short-term effects only and some data sets have been published several times, exaggerating the size of the evidence base (Healy 2012). Also benefits may be due to calming effects of drugs rather than real effects on symptoms. This means evidence of effectiveness is less impressive than it seems.
    • One limitation of antipsychotic drugs is the likelihood of side effects. Typical antipsychotics are associated with dizziness, agitation, sleepiness, weight gain, etc. Long-term use can lead to lip-smacking and grimacing due to dopamine super-sensitivity (= tardive dyskenesia). The most serious side effect is neuroleptic malignant syndrome (NMS) caused by blocking dopamine action in the hypothalamus (can be fatal due to disrupted regulation of several body systems). This means that antipsychotics can do harm as well as good and individuals may avoid them (reducing effectiveness)
    • Another limitation of antipsychotics is that we do not know why they work. The use of most of these drugs is strongly tied up with the dopamine hypothesis and the idea that there are higher-than-usual levels of dopamine in the subcortex of people with sz. But there is evidence that this may not be correct and that dopamine levels in other parts of the brain are too low rather than too high. If so, most antipsychotics shouldn't work. This means that antipsychotics may not be the best treatment to opt for - perhaps some other factor is involved in their apparent success.
    • Furthermore, it is believed that antipsychotics are used in hospital situations to calm people with sz and make them easier for staff to work with. However, calming people distressed by hallucinations and delusions probably makes them feel better and allows them to engage with other treatments (e.g. CBT) and services. On balance then there are clear benefits to using antipsychotics to calm people with sz and in the absence of a better alternative they should probably be prescribed.
    • Atypical antipsychotics:
      Clozapine
      • not available as an injection because of side effects, but taken in tablets and liquid.
      • dosage: typically 300-450mg a day
      Risperidone
      • taken in form of syrup, tablets, or injections which last about 2 weeks
      • dosage: typically 4-8mg a day or max of 12mg a day
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