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Too many seniors with dementia are being prescribed drugs that cause confusion and worsen cognitive function, according to findings of a new study based on Canadian data.

The study, published in the Journal of the American Geriatrics Society in March, found that 60 per cent of seniors living in long-term care institutions take cholinesterase inhibitors, which combat the symptoms of dementia, as well as anticholinergic drugs, which are well-known to cause confusion and other forms of cognitive impairment. Among seniors living in the community, nearly 40 per cent are prescribed cholinesterase inhibitors and anticholinergic drugs. The risks are highest among those seniors seeing multiple physicians.

Dr. Paula Rochon, lead researcher of the study and senior core researcher at Toronto's Institute for Clinical Evaluative Sciences, said the findings should send a message to health-care professionals about the need to more carefully manage the multitude of drugs being prescribed to vulnerable seniors. She and her colleagues conducted the study by analyzing Ontario data from roughly 79,000 seniors living in the community and 12,100 long-term care residents.

Cholinesterase inhibitors, such as donepezil, galantamine and rivastigmine, help damaged nerve endings send messages and can improve or stabilize the symptoms of dementia for a period of time. They do this by preventing the breakdown of acetylcholine in the brain, which leads to increased communication between nerve cells.

Anticholinergics, on the other hand, prevent acetylcholine from functioning properly, which can lead to cognitive impairment.

Anticholinergic drugs are prescribed for a wide range of conditions, including asthma, depression, sleep problems and incontinence. Some anticholinergic drugs commonly prescribed to seniors taking drugs to control dementia in Canada include trazodone, an antidepressant; ranitidine, which decreases production of stomach acid; quetiapine fumarate, used to treat dementia; and risperidone, which is also used to treat dementia.

Even though anticholinergic drugs aren't supposed to be prescribed to individuals with dementia, it happens far too often, said Dr. Larry Chambers, scientific adviser with the Alzheimer Society of Canada.

"It's quite shocking," he said.

On their own, many anticholinergic drugs may not cause cognitive impairment. But many seniors are prescribed numerous anticholinergic drugs at a time, which does put seniors with dementia at risk, according to the study's findings. Researchers use a tool known as the Anticholinergic Risk Scale to determine whether a patient's prescriptions put him or her at risk. In her study, Rochon found that numerous seniors had a risk score of three and above, which is considered high.

For instance, 12 per cent of seniors living in the community had a risk score of three or more, compared with 30 per cent of those living in long-term-care facilities.

There are growing concerns about the overprescribing of powerful medications to seniors, particularly those living in long-term care facilities. A February report from the Canadian Institute for Health Information found that nearly half of all seniors living in long-term care facilities are prescribed antipsychotic drugs such as risperidone.

A major part of the problem, Chambers said, is that there's no system in place in much of Canada to allow physicians to easily look up all of the prescriptions a patient may be taking.

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