Summary: 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).

Summary: Patients with Parkinson's disease (PD) sometimes experience symptoms affecting their movement, such as slowness, tremor, stiffness, and balance or walking problems. Many patients also have other symptoms not related to movement, called non-motor symptoms, which may affect one's mood or emotions, memory or thinking, or cause one to see or hear things that aren't real (hallucinations) or believe thi...

Summary: The purpose of this study is to evaluate the safety and efficacy of 34 mg pimavanserin compared to placebo in patients with Parkinson's disease psychosis (PDP).

Summary: It is hypothesize that patients with clinically diagnosed neurodegenerative diseases will have significantly different receptor occupancy of 5HT2A receptors compared to a healthy age/sex-matched control group. This will be tested by measuring 5HT2A receptor density using the PET radioligand (R)-\[18F\]MH.MZ in both populations.

Summary: This Phase 2 study examines the safety, tolerability, and preliminary efficacy of pimavanserin in individuals with Autism Spectrum Disorder. Male or female participants aged 16 to 40 years of age will be randomized to receive single doses of either placebo or pimavanserin in this randomized, placebo-controlled, cross-over designed study, followed by open label extension.

Summary: Serotonin is an important chemical in the brain that helps control mood, sleep, and appetite. Most antidepressant medications work by affecting serotonin to help improve symptoms. A serotonin receptor is like a lock on the surface of brain cells, and serotonin acts like a key that fits into these locks. When serotonin binds to the receptor, it sends a signal that helps control different functions ...

Summary: This is a preliminary randomized, double-blind, placebo-controlled trial comparing pimavanserin 34mg at bedtime vs. placebo for the treatment of insomnia associated with post-traumatic stress disorder.

Summary: This is an interventional, parallel arm assignment treatment study in individuals with Major Depressive Disorder (MDD). Each individual will be treated with a single dose of pimavanserin or placebo plus a single dose of psilocybin. Evaluations will be taken before dosing and following dosing at several timepoints up to 5 weeks post-dosing.

Summary: The investigators are studying how certain drugs can reduce anger outbursts in people with anger problems. In this study the investigators seek to determine if a single 34 mg (two 17 mg tablets) oral dose of the 5-HT2a receptor blocker, pimavanserin, will reduce aggressive responding in individuals with impulsive aggression (Intermittent Explosive Disorder: IED) on a laboratory task that assesses ...