MAPT and Parkinson disease: In our previous study, we showed that gut injected α‐Syn N103 fibrils propagate to the brain stem along vagus nerve to the DMVN to LC and then to SNpc.[21] In PD, one of the initial areas to undergo neurodegeneration is the LC,[31] moreover, we have reported that norepinephrine metabolite DOPEGAL in the LC activates AEP and pathological Tau aggregation in the LC.[32]