TREM2 and Parkinson disease: Increasing studies have reported that the neuroinflammation caused by microglia in the striatum mediates various central diseases, such as Parkinson’s disease (37), schizophrenia (38), Alzheimer’s disease (39, 40), and other negative affective conditions (41); and the potential molecular mechanisms include IL-13 (42), IL-6 (41), TREM2 (39), BIN1 (39), and toll-like receptors (36).