Fig. 2

Frequencies and distribution patterns of subpial ARTAG. Frequency of subpial ARTAG in different regions (basal brain regions, BBR; lobar regions, LOB; and brainstem regions, BST) in a pooled cohort of non-FTLD-tauopathies (PART+AD+other), PSP, and CBD (a). Note the differences in concomitant involvement of regions. The sequential stages of subpial (SP) ARTAG in the pooled cohort of non-FTLD-tauopathies comprise pattern 1 (b) when basal brain regions show subpial ARTAG first (stage 1) followed by a bidirectional sequence rostrally (lobar) and caudally (brainstem), which two are affected rarely separately (stages 2a or b) and more frequently together (stage 3); pattern 2 (c) when subpial ARTAG in lobar regions or in brainstem appear first (stage 1a or b; two-headed dashed arrows indicate that we do not know which precedes the other); when affected together is stage 2 and finally when additionally basal brain regions are involved is stage 3; and pattern 3 (d) as exemplified by CBD, where subpial tau immunoreactivity of astrocytic feet is the predominant pathology independently of subpial ARTAG in basal brain regions (together representing stage 1) and both are followed by the involvement of the brainstem, representing stage 2. The pathogenesis of subpial astrocyte feet tau immunoreactivity in CBD is most likely different from subpial lobar ARTAG (thus indicated with an asterisk), therefore this sequence could be termed as “masked” bidirectional. This means that the typical subpial TSAs in CBD follow the subpial ARTAG in the basal brain regions (indicated by dashed arrows) are masked by the predominant end-feet tau immunoreactivity