GFAP and Alzheimer disease: In DS, a study in plasma has found pTau-217 and GFAP consistently positively correlated with increased tau tracer binding in the temporal region of amyloid-positive DS individuals (Janelidze et al., 2022), suggesting the potential for a multimodal approach for increased diagnostic accuracy and ability to monitor disease progression as well as contextualizing tau PET results within the current framework of AD criteria.