MLKL and Alexander disease: To determine whether necroptosis is involved in age‐associated AxD, we assessed necroptosis activation by the expression of the phosphorylated forms of MLKL (pMLKL) and RIPK3 (pRIPK3) in different hippocampal subfields, including hilar axons of the DG (Figure 1f–q) and the CA3‐CA1 projecting Schaffer collateral axons (Figure S4).