APOE and Alzheimer disease: We found that APOE4 neurons treated with conditioned media from resting APOE4 astrocytes had similar metabolism to APOE3 neurons treated with media from resting APOE3 astrocytes, but treatment with astrocytic conditioned media from astrocytes challenged with amyloid-β (Aβ), a key pathological protein in AD, caused APOE4 neurons to increase their basal mitochondrial and glycolytic metabolic rates more than APOE3 neurons.