Abnormal misfolding of the proteins τau and amyloid-β (Aβ) leads to the progression of Alzheimer’s disease; traumatic brain injury can be induced by modifying τau, trans active response d(eoxyribo)n(ucleic) a(cid) (TAR DNA) -binding protein-43 (TDP-43), and Aβ proteins; while τau and TDP-43 misfunctioning can subsequently induce epilepsy and various other tauopathies. Here, MAPT is linked to early-onset autosomal dominant Alzheimer disease.