Search

Introduction An Alzheimer's disease (AD) biomarker adjusted for age-related brain changes should improve specificity for AD-related pathological burden. Methods We calculated a brain-age-adjusted “personalized AD cortical thickness index” (pADi) in mild cognitive impairment patients from the Alzheimer's Disease Neuroimaging Initiative. We performed receiver operating characteristic analysis for discrimination between patients with and without cerebrospinal fluid evidence of AD and logistic regression in an independent sample to determine if a dichotomized pADi predicted conversion to AD dementia. Results Receiver operating characteristic area under the curve was 0.69 and 0.72 in the two samples. Three empirical methods identified the same cut-point for pADi in the discovery sample. In the validation sample, 83% of pADi+ mild cognitive impairment patients were cerebrospinal fluid AD biomarker positive. pADi+ mild cognitive impairment patients (n = 63, 38%) were more likely to progress to AD dementia after 1 (odds ratio = 2.9) and 3 (odds ratio = 2.6) years. Discussion The pADi is a personalized, magnetic resonance imaging–derived AD biomarker that predicts progression to dementia., Highlights • The personalized AD cortical thickness index (pADi) is a personalized magnetic resonance imaging–derived, brain-age-adjusted Alzheimer's disease (AD) biomarker. • The pADi accurately identifies mild cognitive impairment patients with cerebrospinal fluid markers of AD. • The pADi was consistent across two independent samples with 1.5T and 3T magnetic resonance imaging data. • An optimal cut-point predicted progression to AD dementia over 1 or 3 years. • The pADi can identify mild cognitive impairment likely due to AD in individual patients.