MAPT and Cognitive impairment: The oligomeric and protofibrillar species are hypothesized to be the most toxic forms [30] and may facilitate tau hyperphosphorylation, disruption of proteasome and mitochondrial function, dysregulation of calcium homeostasis, synaptic failure [31], and glial cell activation [31, 32]; leading to neuronal cell death, neurodegeneration, and cognitive impairment.