A Study of Pimavanserin for the Treatment of Agitation and Aggression in Subjects With Alzheimer's Disease

Inclusion Criteria: 1. Must complete the Week 12 visit in Study ACP-103-032 while continuing to take his/her assigned dose of blinded study drug 2. Can understand the nature of the trial and protocol requirements and provide signed informed consent * from patient, if deemed competent to provide consent * from an appropriate person (e.g. patient's Legally Authorized Representative (LAR) with the patient's assent) if patient is deemed not competent to provide informed consent. 3. Lives at home or in an assisted living or care facility (but has the capacity to visit the clinic as an outpatient) 4. Has a designated study partner/caregiver who is in contact with the patient at least 3 times a week on 3 separate days 5. Female patients must be of non-childbearing potential or must agree to use an acceptable method of contraception or abstinence, during the study, and 1 month following completion of the study 6. The patient and caregiver are willing and able to participate in all schedule evaluations and complete all required tests Exclusion Criteria: 1. Patient was significantly non-compliant in Study ACP-103-032 2. The Investigator becomes aware of an impending and unexpected change in the patient's living situation (e.g., change in caregiver, change in facility, moving from home to facility, moving from one family member or caregiver's home to another) that may cause a major disruption in the patient's behavior 3. Patient or study partner/caregiver has a medical condition (e.g., hearing, vision impairments) that would impair the ability to perform the study assessments. 4. Patient is bedridden or has any significant medical condition that is unstable and would place the patient at undue risk from study drug or study procedures 5. Has clinically significant laboratory abnormalities that would jeopardize the safe participation of the patient in the study 6. Has a Global Clinician Assessment of Suicidality (GCAS) score of 3 or 4 based on Investigator's assessment of behavior since the last assessment