Open-Label Study With Pimavanserin on Activities of Daily Living in Subjects With Parkinson's Disease Psychosis

Inclusion Criteria: 1. Male or female subjects at least 40 years of age 2. Has a Mini-Mental State Examination (MMSE) score ≥19 at Screening 3. Has a diagnosis of idiopathic Parkinson's disease (PD) 4. Has psychotic symptoms that may impair function and are severe enough to warrant treatment with an antipsychotic agent 5. Psychotic symptoms developed after the onset of symptoms of PD 6. If the subject is female, she must not be pregnant or breastfeeding. She must also be of non-childbearing potential (defined as either surgically sterilized or at least 1 year postmenopausal) OR must agree to use TWO clinically acceptable methods of contraception. Exclusion Criteria: 1. Has atypical parkinsonism (Parkinson's plus, multiple system atrophy \[MSA\], progressive supranuclear palsy \[PSP\]), or secondary parkinsonism variants such as tardive or medication induced parkinsonism 2. Has undergone ablative procedures such as a pallidotomy, thalamotomy, or treatment with focused ultrasound, or has an implanted deep brain stimulator 3. Has current evidence of an unstable neurological, cardiovascular, respiratory, gastrointestinal, renal, hepatic, hematologic, or other medical or psychiatric disorder, including cancer or malignancies that, in the judgment of the Investigator, would jeopardize the safe participation of the subject in the study or significantly interfere with the conduct or interpretation of the study 4. Has a history of myocardial infarction, unstable angina, acute coronary syndrome, or cerebrovascular accident within the last 6 months prior to Screening 5. Has any of the following: 1. greater than New York Heart Association (NYHA) Class 2 congestive heart failure 2. Grade 2 or greater angina pectoris (by Canadian Cardiovascular Society Angina Grading Scale) 3. sustained ventricular tachycardia 4. ventricular fibrillation 5. torsades de pointes 6. syncope due to an arrhythmia 7. an implantable cardiac defibrillator 6. Has a known personal or family history of long QT syndrome or family history of sudden cardiac death 7. Requires treatment with a medication or other substance that is prohibited by the protocol 8. Has a body mass index (BMI) \<18.5 kg/m2 or \>35 kg/m2 at Screening or Baseline or known unintentional clinically significant weight loss (i.e., ≥7%) over past 6 months 9. Is suicidal at Screening or Baseline 10. Has a history of a significant psychotic disorder prior to or concomitantly with the onset of PD including, but not limited to, schizophrenia or bipolar disorder 11. Had dementia prior to or concomitantly with the onset of motor symptoms of PD 12. Positive COVID-19 polymerase chain reaction (PCR) or antigen result in the last 2 weeks prior to screening 13. Is judged by the Investigator or the Medical Monitor to be inappropriate for the study for any reason Additional inclusion/exclusion criteria apply. Subjects will be evaluated at screening to ensure that all criteria for study participation are met.