Biological Therapy - A03 Flashcards

1
Q

Evidence for effectiveness

A

One strength of antipsychotics is evidence to support their effectiveness.
There is a large body of evidence to support the idea that both typical and atypical antipsychotics are at least moderately effective in tackling the symptoms of schizophrenia.
Ben Thornley et al. (2003) reviewed studies comparing the effects of chlorpromazine to control conditions. Data from 13 trials with a total of 1121 participants showed that chlorpromazine was associated with better overall functioning and reduced symptom severity as compared to placebo. There is also evidence for the benefits of atypical antipsychotics. In a review Herbert Meltzer (2012) concluded that clozapine is more effective than typical antipsychotics and other atypical antipsychotics, and that it is effective in 30-50% of treatment-resistant cases where typical antipsychotics have failed.
This means that, as far as we can tell, antipsychotics work.

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2
Q

Counterpoint

A

David Healy (2012) has suggested serious flaws with evidence for effectiveness. For example most studies are of short-term effects only and some successful trials have had their data published multiple times, exaggerating the size of the evidence base for positive effects. Also, because antipsychotics have powerful calming effects, it is easy to demonstrate that they have some positive effect on people experiencing the symptoms of schizophrenia. This is not the same as saying they really reduce the severity of psychosis.
This means that the evidence base for antipsychotic effectiveness is less impressive
than it first appears.

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3
Q

Serious side effects

A

One limitation of antipsychotic drugs is the likelihood of side effects.
Typical antipsychotics are associated with a range of side effects including dizziness, agitation, sleepiness, stiff jaw, weight gain and itchy skin. Long-term use can result in tardive dyskinesia, which is caused by dopamine supersensitivity and causes involuntary facial movements such as grimacing, blinking and lip-smacking. The most serious side effect of antipsychotics (particularly typical antipsychotics) is neuroleptic malignant syndrome (NMS). This is believed to be caused when the drug blocks dopamine action in the hypothalamus, an area in the brain associated with the regulation of a number of body systems. NMS results in high temperature, delirium and coma, and can be fatal.
Estimates of its frequency range from less than 0.1% to just over 2%.
This means that antipsychotics can do harm as well as good and individuals who experience these may avoid such treatments (which makes the treatment ineffective).

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4
Q

Mechanism unclear

A

A further limitation of antipsychotics (typical and at least some atypical) is that we do not know why they work.
Our understanding of the mechanism by which antipsychotic drugs work is strongly tied up with the original dopamine hypothesis - the idea that symptoms of schizophrenia are linked to high levels of dopamine activity in the subcortex of the brain. However we now know that this original dopamine hypothesis is not a complete explanation for schizophrenia, and that in fact dopamine levels in other parts of the brain are too low rather than too high. If this is true then most antipsychotics should not work. Given that there are questions over the effectiveness of antipsychotics anyway this adds to the argument that in fact they are ineffective.
This means that at least some of the antipsychotics may not be the best treatment to
opt for - perhaps some other factor is involved in their apparent success.

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