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Acadia’s Alzheimer’s psychosis drug misses main goal of mid-stage study

By Thomson Reuters Sep 24, 2026 | 7:00 AM

Sept 24 (Reuters) – Acadia Pharmaceuticals said on Thursday its experimental drug for psychosis associated with Alzheimer’s missed the main goal of a mid-stage study ​testing whether it could reduce hallucinations and ‌delusions in patients with the condition.

Shares of the drugmaker fell about 12% in premarket trading.

Alzheimer’s disease psychosis affects about 30% of people diagnosed with Alzheimer’s and can cause hallucinations and delusions, ‌increasing ​caregiver burden and the need ⁠for nursing home care.

Here ⁠are more details:

• Acadia said patients receiving a 60-milligram once-daily dose of its drug, remlifanserin, showed greater improvement than those on placebo but the difference was ​not enough for the study to meet its main goal of reducing hallucinations and delusions after ⁠six weeks.

• Acadia said the improvement ⁠between those on the 60-mg dose ​and placebo increased throughout the six-week treatment period.

• A 30-mg ​once-daily dose showed little improvement compared with placebo ‌across study measures.

• However, the drug achieved statistical significance on a key secondary measure that evaluates the overall severity of Alzheimer’s disease psychosis symptoms.

• The company said ⁠it will continue enrolling patients in two ongoing late-stage studies of remlifanserin for Alzheimer’s disease psychosis and stop testing ⁠the 30-mg dose ‌in the program.

• Acadia said the ⁠rates of side effects, serious side effects ​and ‌treatment discontinuations among patients receiving the drug ​were similar ⁠to those seen with placebo.

• The company said remlifanserin showed no apparent adverse effects on patients’ movement or cognitive function, and no deaths were reported among those receiving the drug.

(Reporting by Sahil Pandey in Bengaluru; Editing ​by Diti Pujara)