On the other hand, astro- and microglial reactions are endowed with beneficial role in Alzheimer’s disease environment by stimulating the digestion/clearance of pathogenic Aβ and tau species and, then, by preventing their accumulation into insoluble cerebral lesions, the senile plaques and neurofibrillary tangles. The gene discussed is MAPT; the disease is early-onset autosomal dominant Alzheimer disease.