GFAP and Alzheimer disease: mIns concentration was quantified in a volume located in the precuneus/posterior cingulate cortex (PCC) region, which is an early site of Aβ accumulation and has been recommended as an appropriate region for MRS in studies on Alzheimer’s disease.30 To support inferences about the involvement of astrocytes in the processes under examination, we also quantified plasma glial fibrillary acidic protein (GFAP), a marker of astrocytic activation, which has been shown to correlate with Aβ-PET.31