TREM2 and Alzheimer disease: Thus, several biological processes that have been identified as crucial for the pathogenesis of AD but also other neurodegenerative dementias [14, 21] may not only involve APOE and TREM2, as previously described [67] but also PLCG2. Consequently, taking our present and previous research, it is tempting to speculate that this shared mechanism could include the adaption of microglia to a neurodegenerative environment that may contribute to the protective effect across different neurodegenerative dementias, as hypothesized before.