Alosco ML, et al. - In the present study, researchers analyzed concentrations of total tau (t-tau), phosphorylated tau, and amyloid β_1-42 in cerebrospinal fluid (CSF) and their relationship with repetitive head impacts (RHI) in former National Football League (NFL) players as well as the role of microglial activation (using sTREM2) as a pathogenic mechanism of chronic traumatic encephalopathy. Study participants were 68 former NFL players and 21 controls who had a lumbar puncture to quantify t-tau, p-tau181, amyloid β_1-42, and sTREM2 in the CSF using immunoassays. They found that greater RHI and increased microglial activation were correlated with higher t-tau concentrations in CSF in this sample of former NFL players. It was observed that sTREM2 strengthened the association between exposure to RHI and CSF t-tau.