MAPT and channelopathy: Age-associated tau pathology was confined to the entorhinal cortex.<h4>Conclusion</h4>Despite functional sympathetic impairment evident in reduced MIBG uptake and severe gastrointestinal dysmotility, there was no histologic evidence of sympathetic nerve degeneration or neuronal loss in the enteric plexus, supporting a postsynaptic channelopathy mechanism in AAG.