Psychosis (hallucinations and delusions) is a common problem in Parkinson's disease (PD) and dementia with Lewy bodies (DLB). PD is a common neurodegenerative disorder that causes movement, cognitive, and psychiatric symptoms. DLB is a similar disorder, though causes more severe cognitive and psychiatric problems. Psychosis is highly prevalent among people with PD and DLB, often manifesting as visual hallucinations or paranoid delusions. Up to 60% of people with PD will experience psychosis over the course of their disease. Psychosis is associated with increased mortality, caregiver burden, and poorer quality of life.~More study is needed to determine the best way to treat psychosis in PD and DLB. Currently, both quetiapine and pimavanserin are used in clinical practice for psychosis in PD and DLB. However, few comparison studies have been done and it is unclear if one medication is superior to the other. This will be a clinical trial comparing quetiapine and pimavanserin among patients with psychosis due to PD or DLB requiring initiation of a medication. Patients will be randomized to quetiapine or pimavanserin and improvement in psychosis at 6 months will be compared between the groups.
The primary objective of this study is to determine whether treatment with pimavanserin or quetiapine is associated with a greater improvement in psychosis when used in a routine clinical setting to treat hallucinations and/or delusions due to Parkinson's disease (PD) or dementia with Lewy bodies (DLB) - collectively referred to as Lewy body disease (LBD).