MAPT and Alzheimer disease: Certain studies have reported a rise in sTREM2 levels in patients up to 5 years before the clinical onset of AD (Suárez-Calvet et al., 2016a,b), where these elevated levels also correlate with established neurodegenerative markers such as t-tau/p-tau and Aβ42 (Henjum et al., 2018).