Early-onset Alzheimer Disease Associated With Neuromyelitis Optica Spectrum Disorder.

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune demyelinating disease of the central nervous system. Although recent reports have noted that cognitive impairment is common in NMOSD, little longitudinal information is available on the trajectories of cognitive function in the disease. Here, we report a case of a 55-year-old woman with an 11-year history of NMOSD who visited our memory clinic for progressive memory loss. She was diagnosed with early-onset Alzheimer disease based on amyloid and tau positron emission tomography imaging biomarkers. This is the first report of early-onset Alzheimer disease in a patient with NMOSD. Complications of Alzheimer disease should be considered when patients with NMOSD exhibit rapid cognitive decline. More longitudinal studies of NMOSD with cognitive impairment are needed.