March 10, 1999
Drug Can Prevent Psychosis In Parkinson's Disease
By Gene Emery
BOSTON (Reuters) - The sometimes psychotic side-effects produced by
drugs used to treat Parkinson's disease can be prevented with small
doses of the drug clozapine, researchers report in Thursday's New
England Journal of Medicine.
Between 5 percent and 8 percent of the 50,000 Americans stricken each
year by Parkinson's disease develop some type of psychosis as a result
of treatment, usually with the drug L-dopa. Older drugs designed to
treat psychosis also often make the muscle tremors, stiffness and
weakness of Parkinson's disease even worse.
Dr. Joseph H. Friedman, chief of neurology at Memorial Hospital of Rhode
Island and the study's lead author, told Reuters the findings should be
``very helpful'' to those patients who suffer from psychotic episodes.
``There's no question that this is a big plus,'' he said.
Those stricken by psychosis may become convinced that their spouses are
cheating, or someone is stealing their money. Or they may start having
visual hallucinations, such as witnessing people selling body parts or
seeing a cemetery in a hospital, Friedman said.
His group found that small doses of clozapine, an antipsychotic drug,
can prevent the hallucinations and paranoia.
The researchers found in a study of 60 volunteers at six U.S. medical
centers that clozapine, sold under the brand name Clozaril by Sandoz
Pharmaceuticals, significantly reduced the psychosis without making the
Parkinson's symptoms worse.
``The (Friedman) report describes an important advance in our ability to
treat one of the most disabling conditions encountered in patients with
Parkinson's disease,'' said Dr. Jeffrey Cummings of the UCLA School of
Medicine in an accompanying editorial.
``The addition of clozapine may allow some patients to continue living
at home for longer periods and will facilitate the care of many of those
living in nursing homes,'' Cummings said.
But clozapine must be given with care. In about 1 percent of those who
take it for schizophrenia, it causes a dangerous depletion in white
blood cells, known as agranulocytosis, setting the stage for a
potentially fatal infection.
Even though the Parkinson's sufferers were treated in the study with a
dose 20 times less than that prescribed for schizophrenics, Friedman
said the risk of agranulocytosis ''isn't related to the dose of
clozapine. It's related only to exposure to the drug.''
As a result patients must have their blood tested regularly to watch for
the condition.
But ``if you do the monitoring,'' said Friedman, ``the risks are
incredibly tiny.''
Parkinson's disease is a degenerative brain disorder. About one person
in 200 is affected by the disease. Men are more likely to be affected
than women, and the elderly are particularly at risk. There is no cure
for the disease.
--
Judith Richards, London, Ontario, Canada
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