Sales of anti-psychotic medications have soared in recent years, spurred by the arrival of a new generation of drugs that promised relief from symptoms of dementia with fewer side effects.
But a new Canadian study shows that the new, more expensive drugs -- known as atypical anti-psychotics -- have the same problems as their predecessors, notably causing Parkinson's-like symptoms.
"Our study shows that both the older typical agents, as well as the newer atypical drugs, can lead to Parkinsonism," said Paula Rochon, a scientist at the Institute for Clinical Evaluative Sciences in Toronto.
She said this is worrisome because of the large number of people who are prescribed anti-psychotics.
About 3 per cent of people over the age of 65 in Ontario take the drugs, including as many as one in four residents of nursing homes.
The research, published in today's edition of the Archives of Internal Medicine, shows that patients taking atypical anti-psychotics are three times as likely to develop Parkinson's-like symptoms as those who do not take the drugs.
"These results are really concerning," Dr. Rochon said.
The researcher, who is also a geriatrician at the Baycrest Centre for Geriatric Care in Toronto, said that given the serious side effects, physicians "really need to return to the basic principles of prescribing and determine if the therapy is needed. If it is, then they must choose the therapy with the least side effects and use the lowest dose possible."
Anti-psychotic medication is used to treat various conditions, including bipolar disorder, schizophrenia and symptoms of dementia.
The powerful drugs have shown only a modest improvement in people with dementia and are supposed to be prescribed only to patients who pose a danger to themselves or others.
But there is strong evidence that anti-psychotics are being used increasingly to sedate nursing home residents who suffer even mild forms of dementia.
"The nursing home population, and those with dementia in particular, are a very vulnerable group," Dr. Rochon said. "They are not in a position to advocate very well so we have to be certain these therapies are being prescribed appropriately."
Generally, three atypical anti-psychotics are prescribed to seniors: olanzapine (brand name Zyprexa), risperidone (Risperdal) and quetiapine fumarate (Seroquel).
This summer, Health Canada issued an advisory that patients taking any of these were at increased risk of death.
A recent study in the British Medical Journal also suggested that atypical anti-psychotics may actually speed the decline of patients suffering from dementia, and that it was not at all clear that the benefits outweighed the risks.
Other research has shown anti-psychotics also increase the risk of diabetes, and they can cause movement disorders other than Parkinson's disease.
Dr. Rochon cautioned that patients should not abruptly stop taking these drugs.
But she said the data should serve as a "message to physicians" to think hard about their prescribing habits.
She said "non-drug approaches should always be explored before starting anti-psychotic therapy" and if drugs are prescribed, it should always be at the lowest dose possible.
The new research showed there was a direct correlation between dose and severity of symptoms. ICES scientists followed 57,838 Ontarians over the age of 65 between 1997 and 2001. Of the total, 11,571 were prescribed an atypical anti-psychotic, 14,198 a typical anti-psychotic, while the balance took neither type of drug.
An earlier study published by ICES found that about 80 per cent of patients taking anti-psychotics are now taking the newer atypical versions.
That is up from 10 per cent four years ago.
Across Canada, about 6.2 million prescriptions have been issued for atypical anti-psychotics in the past 12 months. Sales totalled more than $492-million, according to IMS Health Canada, a private company that tracks prescription drug trends.
In 1993, the number of prescriptions for atypical anti-psychotics was about 308,000.