Measuring Cognition in Clinical Trials in Parkinson's Disease, Dementia with Lewy Bodies, and Related Disorders: Roundtable Proceedings and Roadmap for Research.

Emerging research suggests that Parkinson's disease (PD) and dementia with Lewy bodies (DLB) share underlying pathology and may represent a single, biologically defined disease spectrum. Cognitive changes are among the most worrisome symptoms for patients with PD, and are the core feature of DLB. While the cognitive changes experienced by individuals with PD and mild cognitive impairment share some clinical characteristics with patients who have undiagnosed or prodromal DLB, these changes are distinct from other types of dementias, such as Alzheimer's disease. To spur the adaptation of existing cognition-focused measures and the development of new ones to underlie clinical trial endpoints in PD and DLB, the PD/DLB Cognition Roundtable was held on January 10 and 11, 2024, in Washington, D.C. The roundtable brought together representatives from academia and industry, as well as with representatives of regulatory agencies, community partners, patient advocates, and research funders, to build consensus and collaborate on the outcome assessment and trial design methods that will support the development of new treatments for early or mild cognitive changes in disorders on the PD/DLB spectrum. The authors of this document summarize the roundtable, discussing the state of the field for clinical trial design and cognition measures in PD and DLB, promising avenues of research, and perspectives of regulatory agencies.