Question:
In adults with Parkinson’s disease and psychosis, how effective are anti-psychotics, compared to treatment as usual, for treating psychotic symptoms? Which is the most effective and most
tolerable?
Answer:
No definite clinical implications can be made from the available
evidence. There are very few methodologically robust head-to-head
studies, so that it is not possible to determine which
antipsychotic is most effective. Several treatments were compared
with placebo (olanzapine, clozapine, quetiapine, and pimavanserin);
only two treatments reported significant findings. Clozapine showed
significant improvement for some
outcomes
(mean scores on the CGI, and the positive subscore of
PANSS), but somnolence was more frequent with treatment. A
well-conducted study demonstrated that primavanserin significantly
reduced psychotic symptoms in patients with moderate to severe
Parkinson's disease. Although this treatment was well-tolerated,
there was an increase in discontinuation in the treatment group
compared with placebo. One RCT with a very small sample size
compared risperidone with clozapine and found no significant
differences in outcomes between the groups. Two open-label RCTs
compared clozapine with quetiapine, but there were no differences
between groups for any of the behavioural and motor function
parameters evaluated, although in one of the studies, patients
treated with clozapine experienced significantly fewer delusions.
Studies of clozapine reported adverse effects including neutropenia
and leukopenia. These findings are generally consistent with the
systematic review results.
It is clear from the authors of the included studies that
further research into new treatment alternatives for psychosis in
PD is warranted. It has been suggested that RCTs are needed to
evaluate newer atypical antipsychotics (i.e. zipasidone or
aripiprazole) and other treatment strategies (e.g. rivastigmine or
orondansetron). A well-conducted RCT also suggested that
pimavanserin may be a viable alternative for the treatment of
psychosis in Parkinson's disease, but further research is
needed.
To view the full summary, click the Download Document
link to the right.
To view relevant national guidelines, click Related
Links, below.
