A new blood test can tell doctors whether a person has suffered a concussion up to a week after he or she was injured.

　　A study describing the test was published in the journal JAMA Neurology.

　　People who suffer a head injury should rest soon after they are hurt. Doctors say rest is important in helping the brain to heal after the injury.

　　Individuals who have suffered a concussion do not always show symptoms. Experts say those warning signs can be delayed, especially in children.

　　A concussion can lead to a feeling of dizziness, headaches and an inability to sleep. These problems can exist for a long time.

　　Some concussion patients have experienced loss of memory, trouble thinking and feelings of anxiety.

　　Doctors at Orlando Health System in Florida developed the new blood test. It shows if a biomarker is present in a person's blood.

　　The biomarker is called glial fibrillary acidic protein, or GFAP. The protein is only found in the brain and nervous system after a person suffers a concussion.

　　Researchers examined the blood of 600 patients. They found the biomarker in the blood of those who had suffered a head injury.

　　Concussion is a common injury in contact sports. A blood test soon after a head injury could show if an athlete has suffered a concussion. Without the test, sports team officials may not know whether the player has a concussion and could return him or her to the game.

　　I'm Christopher Jones-Cruise.

　　VOA's Jessica Berman reported this story for VOANews. Christopher Jones-Cruise adapted it for Learning English. George Grow was the editor.

　　We want to hear from you. Write to us in the Comments Section, or visit 51VOA.COM.