Discordance Between Cerebrospinal Fluid Biomarkers and Amyloid Positron Emission Tomography in Alzheimer's Sheds Light on Clinical Trial Exclusion Criteria.

Alzheimer's disease (AD) is the most common type of dementia and affects millions of adults over the age of 60 years. Accurate diagnosis relies on multiple modalities, including neuropsychological testing, cerebrospinal fluid (CSF) biomarkers, and amyloid positron emission tomography (PET) imaging. Discordant results between CSF biomarkers and amyloid PET can be seen in up to 15% of cases and can lead to exclusion from clinical trials along with anxiety and confusion for the patient and family. We present two cases of discordance (CSF+, amyloid PET-) that resulted in the exclusion of both patients from two large anti-amyloid monoclonal antibody trials.