Progressively, tau species spread to the CA3 region, and then, through the Schaffer-collateral pathway extend to the hippocampal pyramidal neurons of CA1 followed by prominent aggregation in the neocortex, and at that time point, patients present significant memory/cognitive deficits, marked as the Braak stage V-VI of AD disease progression [17,18,21]. Here, MAPT is linked to Cognitive impairment.