CSF sTREM2 is associated with neuroprotective microglial states early in Alzheimer’s disease and deleterious effects later in the disease trajectory

The MCI and AD stages of the disease showed contrasting associations between sTREM2 and neuroimaging markers for AD pathology. These suggest diverging effects of the microglial response along AD trajectory, with a neuroprotective phase in early AD and a neurotoxic one later on. This could indicate that microglia polarize first towards an anti-inflammatory phenotype before switching to a pro-inflammatory one as neuropathology progresses.