A study has found that drugs commonly used to treat agitation and aggression in people with Alzheimer’s are worthless to most patients.

The drugs, Zyprexa by Eli Lilly, Seroquel by AstraZeneca, and Risperdal from Janssen Pharmaceutical, are no more effective than placebos, according to the study published Thursday in The New England Journal of Medicine. The drugs also put patients at risk for serious side effects. Spokesmen for the companies noted the drugs were not approved by the Food and Drug Administration for use in Alzheimer’s patients.

It is the third major study to find that the drugs, known as atypical antipsychotics, are not as effective as they were portrayed. A British study and a National Institutes of Health study have found that older drugs are just as effective as the newer ones in those with schizophrenia.