In DSAD, one study assessed cholinergic basal forebrain (ChBF) volumetry, describing lower volumes in more advanced AD, associating with cerebrospinal fluid measures of amyloid (amyloid β 42/40), tau (tau phosphorylated at threonine 181), and neurodegeneration (neurofilament light chain) and positive associations with hippocampal volume and cognitive performance when correcting for age.6 Here, MAPT is linked to Alzheimer disease.