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Exhibit 99.1 Acadia Pharmaceuticals Announces Plan for a Resubmission of its Supplemental New Drug Application to U.S. FDA for NUPLAZID® ( pimavanserin ) - Acadia plans to resubmit its sNDA in the first quarter of 2022 - Conference call and webcast to be held today at 4:30 p.m. Eastern Time SAN DIEGO , CA , December 20 , 2021 - Acadia Pharmaceuticals Inc. ( Nasdaq : ACAD ) announced today that it plans to resubmit its supplemental New Drug Application ( SNDA ) for pimavanserin for the treatment of hallucinations and delusions associated with dementia focused on Alzheimer's disease psychosis ( ADP ) . Resubmission of the sNDA to the U.S. Food and Drug Administration ( FDA ) is planned for the first quarter of 2022 . " Following our recent meetings with the FDA , we plan to resubmit our sNDA for pimavanserin , narrowing the proposed indication from dementia- related psychosis to Alzheimer's disease psychosis , " said Steve Davis , Chief Executive Officer . " Our resubmission will include new analyses of existing clinical study data supporting the treatment of hallucinations and delusions associated with Alzheimer's disease . We are aware there are challenges to overcoming our complete response letter , but are pleased with the high level of engagement from the FDA over the last three meetings and their willingness to review our resubmission , allowing us to make our case that pimavanserin should be the first drug approved to treat Alzheimer's disease psychosis . " The resubmission is intended to demonstrate pimavanserin's clinically meaningful benefit in ADP patients , without worsening of cognition or motor function in this elderly population . The resubmission will include data from two positive , placebo - controlled studies that prospectively met their primary endpoints : the pivotal Phase 3 HARMONY study¹ and the -019 study2 . Additional analyses from HARMONY and -019 will also be provided that validate the primary conclusions from each study and address the concerns raised in the FDA's complete response letter . Conference Call and Webcast Information Acadia will discuss this regulatory update regarding the resubmission of the SNDA for pimavanserin for the treatment of ADP via conference call and webcast today at 4:30 p.m. Eastern Time . The conference call can be accessed by dialing 855-638-4820 for participants in the U.S. or Canada and 443-877-4067 for international callers ( reference passcode 3072268 ) . A telephone replay of the conference call may be accessed through January 4 , 2022 by dialing 855-859-2056 for callers in the U.S. or Canada and 404-537-3406 for international callers ( reference passcode 3072268 ) . The conference call will also be webcast live on Acadia's website , www.acadia-pharm.com , in the investors section and archived until January 17 , 2022 . About Alzheimer's Disease Psychosis According to the Alzheimer's Association , over six million people in the United States are living with Alzheimer's disease3 . Studies suggest that 25 to 50 percent of patients diagnosed with Alzheimer's disease have psychosis , commonly consisting of hallucinations and delusions4 . These symptoms may be frequent and severe and may recur over time . A hallucination is defined as a perception - like experience that occurs without an external stimulus and is sensory ( seen , heard , felt , tasted , sensed ) in nature . A delusion is defined as a false , fixed belief that is resolutely held despite evidence to the contrary . Serious consequences have been associated with psychosis in patients with dementia , such as repeated hospital admissions , increased likelihood of nursing home placement , faster progression of dementia , and increased risk of morbidity and mortality5 . There is no FDA approved drug for the treatment of Alzheimer's disease psychosis .