Table 1. Study Results. Shown is the ratio of tryptic (L) to isotope-labeled peptide (H) for all participants included in Study 1 (AD N = 7 and controls N = 10), Study 2 (AD N = 12 and controls N = 14), Study 3 (AD N = 6, PD N = 10, prodromal AD N = 10 and stable MCI N = 15) and Study 4 (AD N = 36, PD N = 11 and controls N = 44).