Antipsychotic drugs prescribed in the hope of reducing agitation or psychotic behavior in patients with Alzheimer's disease are not effective, new research shows, and they may cause intolerable side effects.

Any calming effect that drugs such as Eli Lilly's Zyprexa, AstraZeneca's Seroquel and Janssen Pharmaceutical's Risperdal might provide is offset by the intolerable side effects they cause in many patients, according to Dr. Lon Schneider of othe University of Southern California, who led the research.

The side effects include sedation and confusion, which can heighten the risk of falls, as well as tremors similar to those that afflict Parkinson's patients.

Although the US Food and Drug Administration has not approved these antipsychotics to treat Alzheimer's disease, doctors frequently prescribe them off-label for patients suffering from disabling agitation, delusions or hallucinations.

The drugs' manufacturers have said they do not recommend using them for this purpose.

The National Institute of Mental Health in Bethesda, Md., funded the research.

Agitation, depression and psychotic behavior can have a severe impact on the quality of life of Alzheimer's patients and their caregivers. These are common and disturbing occurrences among this population. Experts recommend making adjustments to the patient's environment and routine rather than medicating those who exhibit these trying symptoms.