MAPT and supranuclear palsy, progressive, 1: Increased cortical tau pathology has also been documented in PSP variants with cortical features including ‘atypical’ PSP with progressive apraxia of speech and non-fluent aphasia 42, PSP-bvFTD 11,43, and, together with PSP-CBS, these clinical phenotypes are collectively referred as the ‘cortical’ PSP variants 44.