This study will evaluate the safety and efficacy of pimavanserin 40 mg compared to placebo in patients with Alzheimer's disease psychosis.

Inclusion Criteria:

• Patient must be 50 years of age or older with NINCDS-ADRDA defined possible or probable AD
• Patient must have psychotic symptoms that developed after the diagnosis of AD was established. These symptoms must include visual and/or auditory hallucinations, and/or delusions
• Patient must have been a nursing home resident for ≥ 4 weeks prior to randomization, not bedridden and expected to remain in the facility throughout the study
• Patient must have actively experienced and verbally communicated psychotic symptoms during the month prior to the Screening visit and weekly during the previous 2 weeks prior to Baseline
• If patient is on acetylcholinesterase inhibitor (AChEI) therapy and/or memantine, must be on stable doses for 3 months prior to the Baseline visit and during the study
• Patient is willing and able to provide informed consent. If the subject is unable to provide written consent due to the severity of dementia, consent must be given by a legally authorized representative

Exclusion Criteria:

• Patient has a history of significant psychotic disorders prior to or concomitantly with the diagnosis of Alzheimer's disease including, but not limited to, schizophrenia or bipolar disorder
• Patient is unable to communicate verbally
• Patient has current evidence of a serious and/or unstable cardiovascular, respiratory, gastrointestinal, renal, hematologic or other medical disorder, including cancer or malignancies, which would affect the patient's ability to participate in the study
• Patient has had a myocardial infarction in the last six months
• Patient has moderate to severe congestive heart failure
• Patient has any surgery planned during the screening, treatment, or follow-up periods that could interfere with participation in the study per the protocol assessments

Patients will be evaluated at screening to ensure that all criteria for study participation are met. These evaluations will include specific measures of psychosis severity, delirium, dementia, cardiovascular condition, and pregnancy status. Patients may be excluded from the study based on these assessments (and specifically if it is determined that their baseline health and psychiatric condition do not meet all protocol-specified entry criteria).

12 weeks

From the time the informed consent was signed, adverse events were recorded in the subject's source documents and entered into the appropriate eCRF pages at the Screening visit, at visits on Study Days 1, 15, 29, 43, 64 and Day 85, and at the 4-week follow-up phone call.