In general, neurodevelopmental studies of diffusion tensor imaging parameters have found FA to be increasing and mean diffusivity to be decreasing in key WM tracts throughout adolescence (Barnea-Goraly et al., 2005; Mukherjee et al., 2002; Schmithorst & Holland, 2007; Schmithorst, Holland, & Dardzinski, 2008; Snook, Paulson, Roy, Phillips, & Beaulieu, 2005). This pattern has been most often interpreted in relation to the increases in myelination associated with maturation previously observed in postmortem studies, although the magnetization transfer findings described above suggest that it may also be related to changes in other structural components.
