In the present study, we found that APP phosphorylation at Tyr increased in neurons from nine of 10 AD patients but not in healthy volunteers or in one patient with FTD, further substantiating the pathophysiological significance of APP Tyr phosphorylation as an early sign of AD and pointing to the therapeutic targeting of APP Tyr phosphorylation as a potential novel strategy in AD treatment. Here, APP is linked to Alzheimer disease.