TREM2 and Alzheimer disease: High levels of Trem2 have been reported to be a sign of poor prognosis in Alzheimer’s disease (AD) and a mediator of microglia hyperactivation in neuropathic pain [72,73,74], whereas Gdf15, a mediator of macrophage inhibitory cytokine-1 (MIC-1), has been reported to an important marker of mortality in the aged population and stroke patients [75,76,77].