MAPT and Alzheimer disease: While more investigation in the human is required to confirm microglial association with C1q-mediated tagging of synapses, in normal aging [300] and in tauopathy patients [75], C1q is dramatically upregulated and is shown to co-localize with hyperphosphorylated tau, plaques and neurofibrillary tangles in AD brain sections [1, 219, 282].