LINCOLN, Neb. (AP) — Nebraska’s chief medical officer is warning young athletes about the dangers of suffering a concussion.

Dr. Joann Schaefer said Monday that concussions are sometimes more serious than athletes, coaches and parents sometimes realize. Players who have received multiple concussions are more likely to have thinking problems, depression, dementia and other brain-related issues. But she says 90 percent of athletes who experience a single minor concussion usually recover within a few days or weeks.

Short-term symptoms can include headaches, nausea, blurred vision and memory problems.

Nebraska’s Concussion Awareness Act took effect on July 1. The state law requires concussion education for coaches, parents and players.