Psychosis is common across dementia types with a prevalence of 20% to 70%. 
Currently, no pharmacologic treatment is approved for dementia-related 
psychosis. Atypical antipsychotics are frequently used to treat these disorders, 
despite significant safety concerns. Pimavanserin, a selective 5-HT2A inverse 
agonist/antagonist, was approved in the U.S. for treating hallucinations and 
delusions associated with Parkinson's disease psychosis (PDP). Patients in the 
pimavanserin group experienced a significant (p=0.001) improvement in Scale for 
the Assessment of Positive Symptoms - Parkinson's disease (SAPS-PD) scores vs. 
placebo. In a subgroup analysis of patients with cognitive impairment (MMSE 
score ≥21 but ≤24), the observed improvement on the SAPS-PD with pimavanserin 
(N=50) was also significant (p=0.002) and larger than in the overall study 
population without an adverse effect on cognition. In a Phase 2 study with 
pimavanserin in Alzheimer's disease psychosis, pimavanserin significantly 
(p=0.045) improved psychosis at Week 6 vs. placebo on the NPI-NH Psychosis Score 
(PS). In a prespecified subgroup of patients with a baseline NPI-NH PS ≥12, a 
substantively larger treatment effect (p=0.011) was observed vs. participants 
with NPI-NH PS <12. The results of these studies in cognitively impaired 
patients with PDP provided the scientific foundation for an ongoing study of 
pimavanserin for treating patients with dementia-related psychosis associated 
with the most common neurodegenerative disorders. The study uses a 
relapse-prevention design with the endpoint of time-to-relapse of psychosis to 
evaluate the long-term efficacy and safety of pimavanserin as a potential 
treatment for hallucinations and delusions of dementia-related psychosis.