MAPT and Alzheimer disease: For instance, one study found that elevated p-tau was associated with smaller volumes of the hippocampus, amygdala and entorhinal cortex only in amyloid positive individuals.24 Another study reported that individuals with amyloid positivity had higher regional volumes compared with controls without neurodegeneration.25 Additionally, the impact of CSF Alzheimer’s disease biomarker groups on grey matter structural connectivity (aka.