Extension Study of Pimavanserin in Adult Subjects With Neuropsychiatric Symptoms Related to Neurodegenerative Disease

Inclusion Criteria:

1. Subject satisfied all entry criteria for the antecedent pimavanserin study

2. Subject completed the antecedent study; or was participating in a pimavanserin study
that the Sponsor ended early

3. Has a designated study partner/caregiver who meets the following requirements:

1. In the Investigator's opinion, is in contact with the subject frequently enough
to accurately report on the subject's symptoms and whether or not the subject is
taking the study drug

2. In the Investigator's opinion, is considered reliable in providing support to the
subject to help ensure compliance with study treatment, study visits, and
protocol procedures

3. Is fluent in the local language in which study assessments will be administered

4. Agrees to participate in study assessments, has the capacity to provide informed
consent, and provides written consent to participate in the study

4. Subject is willing and able to provide informed consent.

5. 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 a clinically acceptable method of
contraception or be abstinent during the study and 1 month following completion of the
study.

Exclusion Criteria:

1. Subject is judged by the Investigator or the Medical Monitor to be inappropriate for
the study, due to AEs, medical condition, or noncompliance with investigational
product or study procedures in the antecedent study, or is judged to be a danger to
self or others

2. Is in hospice, is receiving end-of-life palliative care, or has become bedridden

3. Has any of the following ECG results at the EOT/ET visit of the antecedent study:

a. If the subject is not on citalopram, escitalopram, or venlafaxine:

i. QTcF >450 ms, if QRS duration <120 ms

ii. QTcF >470 ms, if QRS duration ≥120 ms

b. If the subject is on citalopram, escitalopram, or venlafaxine:

i. QTcF >425 ms, if QRS duration <120 ms

ii. QTcF >450 ms, if QRS duration ≥120 ms

4. Has a heart rate <50 beats per minute. If bradycardia is secondary to iatrogenic or
treatable causes and these causes are treated, a heart rate assessment can be repeated
at the EOT/ET visit of the antecedent study.

5. Has clinically significant laboratory abnormalities in the antecedent study that, in
the judgment of the Investigator or Medical Monitor, would either:

1. jeopardize the safe participation of the subject in the study; OR

2. would interfere with the conduct or interpretation of safety or efficacy
evaluations in the study

6. Is suicidal at Visit 1 (Baseline)

7. Has developed a medical condition that in the judgment of the Investigator, would
increase the risk associated with taking study medication or significantly interfere
with the conduct or interpretation of the study

8. Requires treatment with a medication or other substance that is prohibited by the
protocol

9. Has a significant sensitivity or allergic reaction to pimavanserin or its excipients

10. Is an employee of ACADIA, or has a family member who is an employee of ACADIA

Additional inclusion/exclusion criteria apply. Patients will be evaluated at screening to
ensure that all criteria for study participation are met. 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 pre-specified entry criteria).