Targeting Psychosis in Alzheimer’s Disease

Episode Summary

Executive Summary: The episode examines Alzheimer’s disease psychosis as an under-recognized but highly consequential treatment target, with Acadia’s Elizabeth Thompson explaining why hallucinations and delusions can drive caregiver burden, hospitalization, and nursing-home placement. She outlines remlefanserin (ACP-204), a next-generation 5-HT2A inverse agonist designed to improve efficacy and tolerability versus Nuplazid, and discusses trial design, biomarkers, and the broader resurgence of investment in neuroscience.

Main Topics: Alzheimer’s disease complexity and drug-development challenges (Priority: 5/5): Thompson explains that Alzheimer’s is multifactorial, with genetic, inflammatory, vascular, and overlapping-disease contributions, making timing, patient selection, and trial design difficult. Psychosis in Alzheimer’s as a distinct therapeutic target (Priority: 5/5): The conversation reframes hallucinations and delusions as common, burdensome symptoms that independently worsen outcomes and deserve direct treatment, not just cognitive-focused therapy. Clinical and caregiver impact of psychosis (Priority: 5/5): Psychosis is linked to safety risks, crisis-driven care, emergency utilization, and earlier nursing-home placement, often becoming the tipping point for families. Remlefanserin (ACP-204) and the 5-HT2A mechanism (Priority: 5/5): Acadia’s experimental therapy is positioned as a next-generation antipsychotic built on Nuplazid’s mechanism but with improved dosing flexibility, faster steady state, and potentially better efficacy. Phase 2 development strategy and biomarkers (Priority: 4/5): The ongoing randomized, double-blind, placebo-controlled Phase 2 study enrolls biomarker-confirmed Alzheimer’s patients with baseline psychosis and uses SAPS H&D as the primary endpoint. Commercial and strategic implications for neurology (Priority: 4/5): Thompson argues that Acadia’s commercial experience in neurology and rare disease helps shape trials around patient, caregiver, physician, and payer needs, while the broader field benefits from renewed investment and better biology. Global diagnosis and reimbursement variability (Priority: 3/5): She notes major regional differences in diagnosis, stigma, standards of care, and reimbursement, which will affect future adoption and commercialization.

Key Arguments: Alzheimer’s disease is not a single-pathway disorder; its complexity and long preclinical phase have historically made effective drug development difficult. Psychosis in Alzheimer’s is common and clinically meaningful, affecting function and caregiver burden independently of cognition. Treating cognition alone misses a major driver of morbidity and institutionalization. Current off-label antipsychotics can worsen cognition, gait, or motor function and carry safety concerns in elderly patients. 5-HT2A inverse agonism is supported by prior clinical experience and may treat hallucinations/delusions without broad CNS suppression. Remlefanserin was designed to improve on Nuplazid by reducing QT concerns, enabling higher exposures, and potentially improving efficacy. Biomarker confirmation of Alzheimer’s disease is increasingly important for trial enrollment and future clinical diagnosis. A successful therapy could reduce crises, improve safety, lower caregiver stress, and delay nursing-home placement. Acadia’s commercial and R&D experience supports a “start with the end in mind” approach that aligns development with real-world value. Growing neuroscience investment reflects genuine progress in biology, biomarkers, and regulatory success rather than a purely cyclical surge.

Data Points: Prevalence of psychosis in Alzheimer’s disease: ~30% - Thompson says hallucinations and delusions affect about 30% of patients over the course of Alzheimer’s disease. Phase 1 participants: >200 - Remlefanserin’s Phase 1 program has included more than 200 participants, including healthy volunteers and elderly patients. Phase 2 target enrollment: a little over 300 patients - The ongoing Alzheimer’s disease psychosis Phase 2 trial is randomized, double-blind, and placebo-controlled. Potential data readout window: August to October of this year - Thompson says the Phase 2 Alzheimer’s psychosis data may be available in that timeframe. U.S. diagnosis-rate variation: up to 2-fold difference - She cites geographic variation in Alzheimer’s diagnosis rates even within the United States. Recent Alzheimer’s acquisition activity: $15–20 billion - Thompson references this as the scale of Alzheimer’s-related acquisitions over the last few years.

Pivotal Quotes: "Psychosis, which is hallucinations and delusions, is actually very common, and it affects something like 30% of patients over the course of Alzheimer's disease." — Elizabeth Thompson: Explaining why psychosis is a major and under-recognized treatment target in Alzheimer’s disease. "What we're trying to do is look for something that addresses the hallucinations and delusions without some of the broad blockade that can compromise overall brain function." — Elizabeth Thompson: Describing the rationale for remlefanserin versus broader off-label antipsychotics. "Alzheimer's disease psychosis is under-recognized, inconsistently managed, and a major driver of burden at both the individual and the societal level." — Elizabeth Thompson: Summarizing the unmet need and the case for better diagnosis and treatment globally.

Implications: If remlefanserin succeeds, Alzheimer’s psychosis could become a recognized, treatable condition with clearer trial standards and better care pathways, potentially reducing crises, caregiver burden, and institutionalization while strengthening confidence in neuroscience investment.