The earliest signs of brain damage in athletes? Listen for them.

Even if a doctor strongly suspects that an athlete’s confusion or memory loss is related to C.T.E., proof can only be obtained on autopsy.

Now a small study of National Football League players suggests another possibility: that the signs of C.T.E. may be found with a low-cost, noninvasive test that tracks changes in conversational language years before symptoms appear.

If it works, the linguistic test also would be valuable in assessing the effectiveness of treatments to prevent cognitive damage because of C.T.E. or to slow its progression.

In the study, to be published this week in the journal Brain and Language, researchers at Arizona State University tracked a steeper decline in vocabulary size and other verbal skills in 10 players who spoke at news conferences over an eight-year period, compared with 18 coaches and executives who had never played professional football and who also spoke in news conferences during the same period.