Profound LC-noradrenergic neuronal and fiber loss, as well as neuropathological burdens of hyperphosphorylated-tau (p-tau), amyloid-beta (Aβ) and alpha-synuclein (α-syn), have been described in AD and PD, accompanied by reduced cortical noradrenergic innervation and in turn reduced cortical noradrenaline levels [29, 30]. Here, MAPT is linked to Parkinson disease.