Extended Data Fig. 3 |. Longitudinal serum NfL and bifurcation of mutation carriers from non-carriers.

a, Spaghetti plot showing longitudinal serum NfL for non-carriers (NC, n = 63, blue) and mutation carriers (MC, n = 133, red) as a function of EYO. These are the same data as in Fig. 2a but with a logarithmic scale on the y axis to better appreciate the changes during the presymptomatic stage (for details, see Fig. 2a). b, Difference of posterior distribution for serum NfL rate of change between mutation carriers and non-carriers, as a function of EYO (n = 196). The solid red line depicts the median of the difference distribution, and the shaded area represents the 99% equal-tailed credible intervals. EYO was considered statistically significant if the 99% equal-tailed credible intervals of the posterior distribution did not overlap 0 (16.2 years before EYO). c, Individual estimated rate of change in serum NfL (same data as in Fig. 2b, n = 63 for non-carriers and n = 133 for mutation carriers). A regression analysis was performed with two breaks of slope (see Methods for calculation). With this model the first bifurcation point was found at −18.6 years before EYO, the second at −5.8 years before EYO.