Research ReportP50: A candidate ERP biomarker of prodromal Alzheimer׳s disease

•We investigated the P50 component as a biomarker of Alzheimer׳s disease (AD).•Participants included non-demented patients with mild cognitive impairment (MCI).•P50 amplitude was larger in amyloid-positiverelative to amyloid-negative patients.•P50 amplitude predicted cerebrospinal fluid amyloid status in the MCI patients.•This is consistent with MCI to AD converters having shown larger P50 at baseline.•P50 may prove to be a useful biomarker for early, even pre-symptomatic, AD.

IntroductionReductions of cerebrospinal fluid (CSF) amyloid-beta (Aβ42) and elevated phosphorylated-tau (p-Tau) reflect in vivo Alzheimer׳s disease (AD) pathology and show utility in predicting conversion from mild cognitive impairment (MCI) to dementia. We investigated the P50 event-related potential component as a noninvasive biomarker of AD pathology in non-demented elderly.Methods36 MCI patients were stratified into amyloid positive (MCI-AD, n=17) and negative (MCI-Other, n=19) groups using CSF levels of Aβ42. All amyloid positive patients were also p-Tau positive. P50s were elicited with an auditory oddball paradigm.ResultsMCI-AD patients yielded larger P50s than MCI-Other. The best amyloid-status predictor model showed 94.7% sensitivity, 94.1% specificity and 94.4% total accuracy.DiscussionP50 predicted amyloid status in MCI patients, thereby showing a relationship with AD pathology versus MCI from another etiology. The P50 may have clinical utility for inexpensive pre-screening and assessment of Alzheimer׳s pathology.