Figure 1.

Summary figure of diffusion-weighted imaging (DWI) studies investigating structural connectivity in narcolepsy. Regions were generally included in case there were at least three independent studies indicating white matter changes within this region in people with narcolepsy compared to controls. Reported results were limited to reduced structural connectivity in narcolepsy as the vast majority of studies solely reported reduced structural connectivity. Reported differences could reflect any DWI outcome measure that represents white matter integrity, such as fractional anisotropy (FA) or mean diffusivity/apparent diffusion coefficient (MD/ADC). The numbers between brackets correspond to the reference numbers of the studies. The study by Chen et al. [10] did not divide narcolepsy into type 1 and type 2 when comparing structural connectivity to controls. Post hoc comparisons between narcolepsy type 1 and type 2 did not reveal differences between narcolepsy subtypes, and the study by Chen et al. [10] was thus reported for both the “NT1 < HC” and the “NT2 < HC” contrasts. HC, healthy controls; NT1, narcolepsy type 1; NT2, narcolepsy type 2; WM, white matter.