The Food and Drug Administration on Wednesday approved a long-awaited blood test to detect concussions in people and more quickly identify those with possible brain injuries. The test works by measuring the levels of proteins released from the brain into blood. In a statement announcing the approval, the F.D.A. said that the brain trauma indicator was able to predict the presence of intracranial lesions on a CT scan 97.5 percent of the time, and those who did not have such lesions 99.6 percent of the time. Read more here.