Acute plasma tau relates to prolonged return to play after concussion

Objective: To determine whether tau changes after sport-related concussion (SRC) relate to return to play (RTP). Methods: Collegiate athletes underwent preseason plasma sampling and cognitive testing and were followed. After a SRC (n = 46), athletes and controls (n = 37) had sampling at 6 hours, and at 24 hours, 72 hours, and 7 days after SRC. A sample of 21 nonathlete controls were compared at baseline. SRC athletes were grouped by long (>10 days, n = 23) and short (≤10 days, n = 18) RTP. Total tau was measured using an ultrasensitive immunoassay. Results: Both SRC and athlete controls had significantly higher mean tau at baseline compared to nonathlete healthy controls (F 101,3 = 19.644, p < 0.01). Compared to SRC athletes with short RTP, those with long RTP had higher tau concentrations overall, after controlling for sex (F 39,1 = 3.59, p = 0.022), compared to long RTP athletes, at 6 (p < 0.01), 24 (p < 0.01), and 72 hours (p = 0.02). Receiver operator characteristic analyses showed that higher plasma tau 6 hours post-SRC was a significant predictor of RTP >10 days (area under the curve 0.81; 95% confidence interval 0.62-0.97, p = 0.01). Conclusions: Elevated plasma tau concentration within 6 hours following a SRC was related to having a prolonged RTP, suggesting that tau levels may help inform RTP.