Taking antipsychotic drugs significantly increases the risk of premature death among Alzheimer's patients, a new study indicates.

Researchers analyzed data from almost 58,000 people in Finland diagnosed with Alzheimer's disease between 2005 and 2011.

Slightly more than a quarter of the Alzheimer's patients took antipsychotic drugs. The study found they had a 60 percent higher risk of death than those who didn't take the drugs.

The risk of death was highest when patients first started taking antipsychotics, but the increased risk persisted with long-term use of the drugs.

Patients who took two or more antipsychotic drugs at the same time were nearly twice as likely to die early than those who took one antipsychotic.

Although the study found an association between antipsychotic drug use and a higher risk of dying, it cannot prove a cause-and-effect link.

But, the researchers -- led by Marjaana Koponen, a doctoral student from the School of Pharmacy at the University of Eastern Finland -- said their findings support previous studies. The first warnings about increased risk of death among Alzheimer's patients taking antipsychotics were issued more than 10 years ago.

The new study confirms current recommendations that antipsychotic drugs should be used only for the most difficult behavioral symptoms of dementia, such as agitation and aggression, and that length of use should be limited, the researchers said.

Also, patients should be given the lowest possible doses, and should not be given two or more antipsychotics at the same time.

The study was published recently in the Journal of Alzheimer's Disease.