NRGN and early-onset autosomal dominant Alzheimer disease: Of note, the pattern of differently altered BACE1 and Ng levels in A+/T−/N− and A+/T+/N+ groups resulted in a stage-wise elevation of Ng/BACE1 ratios through the Alzheimer’s disease continuum and was more strongly associated with baseline memory performance and later decline than Ng or BACE1 alone.