The study aimed to assess eligibility for donanemab phase 3 trial in participants of the Mayo Clinic Study of Aging with mild cognitive impairment (MCI) or mild dementia consistent with Alzheimer's disease (AD) clinical syndrome, positive brain amyloid burden, and available tau PET. There were 817 study participants, 60–85 years old, with MCI or dementia consistent with AD clinical syndrome. Applying the Mini-Mental State Examination criteria (20 to 28) and excluding participants with imaging contraindications reduced the sample to 769; 275 participants had amyloid PET available, of whom 130 had also tau PET at the same visit; 56 participants were amyloid positive, had tau PET available at the same visit, and of those, 27 had evidence of tau pathology measured by 18F-flortaucipir PET imaging. Additional eligibility criteria reduced the eligible participants to 23 % (13 out of 56 participants). Neuroimaging findings, central nervous system exclusions, and history of malignancy were the major exclusions.