Evidence is mounting that repeated concussions can do long-term harm to the brain. Athletes who play contact sports are particularly at risk. But a concussion can be difficult to diagnose, and many sports teams, especially those at the youth level, lack medical personnel. Neurology researchers at the University of Pennsylvania think they may have found a solution—an easy-to-use two-minute reading test that can assess the likelihood that a concussion has occurred.

The test was originally designed to evaluate reading skills in children, but it also catches problems with vision and eye movements, which makes it useful for studying concussions. The test consists of a series of numbers arranged in zigzagging patterns on cards, which subjects read from left to right as quickly as possible. The Pennsylvania researchers tried out the test on boxers and mixed martial arts fighters in a study published in Neurology earlier this year and found it worked well as a predictor of head injury.

The researchers gave the fighters the test before and after a match. Typically people can complete the test faster the more times they take it, says Laura Balcer, a neurologist and a lead author of the study. But the athletes who had experienced head trauma during their fights read the cards more than 11 seconds slower when they took the test a second time. Fighters who had lost consciousness fared especially poorly, worsening by 18 seconds on average.

Now Balcer and her collaborators are studying the test’s ability to predict concussions in athletes who play football and other contact sports. Their goal is to create an evaluation tool that could serve as an early warning sign for coaches, who would need only the cards and their stopwatch to determine whether a player needs to be sent to a doctor.