Figure 5.

Myelin water fraction (MWF) as a function of age for white matter throughout the entire brain. Left panel: results obtained on a subset of participants covering a similar age range as in a previous study (Arshad, Stanley, and Raz 2016), that is, excluding participants over age 75. Right panel: results obtained from our full dataset, that is, incorporating all participants. The coefficient of determination, R², and the significance of the linear regression model, p, are reported. It is readily seen that exclusion of the oldest participants, that is, over 75 years, shifts the apparent age of maximum myelination derived from the fit toward late ages; this partially explains the discrepancy reported in the literature regarding the apparent age of maximum myelination (Fjell et al. 2010). Of note, a similar effect was observed in most ROIs.