Alzheimer’s disease drug development has long focused on slowing memory loss, but for many families, the tipping point that makes home care impossible is not cognition—it is psychosis. Hallucinations and delusions in Alzheimer’s are a distinct, prevalent, and under-recognized target for therapy. We spoke to Elizabeth Thompson, executive vice president and head of R&D at Acadia Pharmaceuticals, about the biology behind psychosis in dementia, the company’s experimental therapy to treat the condition in people with Alzheimer’s disease, and the forces reshaping the drug development landscape to enable the development of such treatments.