Although atypical antipsychotic medications are generally beneficial for patients suffering from Alzheimer's-related aggression, agitation, or psychosis, according to one study these effects appear to be outweighed by adverse effects, some severe enough to warrant discontinuation of treatment. Experts randomized adjusted doses of olanzapine, risperidone, quetiapine, and placebo among 421 Alzheimer's patients and observed their progress. Overall, length of time until discontinuation of treatment didn't vary significantly, ranging from 5.3 weeks (quetiapine) to 8.1 weeks (olanzapine). Treatment discontinuation caused by lack of efficacy ranged from less than 10 weeks (quetiapine and placebo) to more than 22 weeks (olanzapine and risperidone). Adverse effects and intolerability led to discontinuation in only 5% of those receiving placebo, as compared with 16% of quetiapine patients, 18% of risperidone patients, and 24% of patients taking olanzapine. The most commonly reported adverse effects were weight gain, sedation, and confusion. In addition, some patients experiencing psychosis found their condition worsened over time.

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