People with Alzheimer's who are prescribed some antipsychotic drugs for agitation and delusions receive few benefits and many stop taking the medication because of the side-effects, a long-term study suggests.

Almost three-quarters of Alzheimer's patients show delusions or aggression that may cause them to lash out, making it difficult for their families to care for them at home.

Doctors commonly prescribe atypical antipsychotics such as Zyprexa (olanzapine), Seroquel (quetiapine) and Risperdal (risperidone) that were developed for schizophrenia to control the symptoms.

The drugs aren't approved for use in dementia, and there has never been strong evidence that the medications are effective for Alzheimer's patients. 

In the first major comparison of the drugs on 421 patients outside nursing homes, researchers in the U.S. found 82 per cent dropped out, many because they couldn't tolerate adverse reactions to the drugs, such as sedation, muscle stiffness or spasms, and confusion.

Between 26 and 32 per cent of those taking the medications improved, compared with 21 per cent among those prescribed a placebo, although symptoms naturally vary over time, the researchers report in Thursday's New England Journal of Medicine.

The antipsychotic medications "are somewhat effective, but overall the efficacy is offset by adverse events that resulted in discontinuing the medication," said the study's lead author, Dr. Lon Schneider of the University of Southern California.

Participants stopped taking the drugs within five to eight weeks on average. They were followed for nine months, longer than previous studies. The U.S. government paid for the study and drug manufacturers supplied the medications.  

There were five deaths reported among those receiving the medication, compared with two in the placebo group. The causes of death were not provided.

Restricted role for medications

About one-quarter of patients in nursing homes are given the drugs to keep them calm, said Dr. Paula Rochon, a senior scientist at Toronto's Centre for Geriatric Care, who led Canadian research on the use of atypical antipsychotics.

Rochon welcomed the research, which also concluded there may be a small group of people who will benefit from the drugs since there are so few options. 

"I think there's still a role for these therapies but it's a restricted role," Rochon said. "We have to find where they're more suited for drug therapies like this and where other options are better."

When it is appropriate to prescribe the drugs, Rochon recommended using the smallest possible dose to prevent serious side-effects, and monitoring patients carefully to see if it is helping. 

Gentle giant reappears

Colleen Callaghan of Calgary said she was opposed to her husband Tom taking the drugs, even though he kicked her when she tried to take his pants off, backed her into a corner and put his fist in her face. The doctors convinced her to try Seroquel as he deteriorated.

"I noticed a remarkable difference in him once he was on the medication," Callaghan recalled. "It helped him, because it meant that he was no longer in that state of agitation, he was more himself."

Callaghan said she was able to care for him until his death three weeks ago in part because of the medication. Toward the end, she was able to lower his dose,  and she saw glimpses of her "gentle giant."

With files from the Associated Press