Chen TB, Lai YH, Ke TL, et al. - Researchers conducted this longitudinal study to examine the temporal trajectories of plasma biomarkers in individuals with mild cognitive impairment (MCI) and patients with Alzheimer disease (AD) relative to healthy controls (HCs). Eighty-two candidates (31 HCs, 33 MCI patients, and 18 AD patients) were registered. Levels of plasma Aβ and tau shift over the AD spectrum in a dynamic, nonlinear, nonparallel manner. Changes in the concentration of plasma Aβ are time-dependent, whereas changes in levels of hyperphosphorylated tau protein are parallel to the clinical progression of MCI. Whether the diagnostic effectiveness can be improved by combining multiple plasma markers or by combining plasma markers with other diagnostic biomarkers remains to be clarified.