IMPORTANCEPersons with dementia and Parkinson disease (PD) are vulnerable to disruptions in health care and services. OBJECTIVE To examine changes in health service use among community-dwelling persons with dementia, persons with PD, and older adults without neurodegenerative disease during the first wave of the COVID-19 pandemic. DESIGN, SETTING, AND PARTICIPANTS Repeated cross-sectional analysis using population-based administrative data among community-dwelling persons with dementia, persons with PD, and adults 65 years and older at the start of each week from March 1 through the week of