NPR – A little spit may help predict whether a child's concussion symptoms will subside in days or persist for weeks.

A test that measures fragments of genetic material in saliva was nearly 90 percent accurate in identifying children and adolescents whose symptoms persisted for at least a month, according to a study published Monday in JAMA Pediatrics.

That's in contrast to a concussion survey commonly used by doctors that was right less than 70 percent of the time.

Read more at NPR.