<unk> , a type of mild traumatic brain injury, are a frequent concern for those playing<unk> s, from children and teenagers to professional athletes. Repeated<unk>  are a known cause of various neurological disorders, most notably chronic traumatic encephalopathy (CTE), which in professional athletes has led to premature retirement, erratic behavior and even suicide. A<unk> s-related<unk> is currently defined as a "complex pathophysiological process affecting the brain, induced by biomechanical forces". Because<unk>  cannot be seen on X-rays or CT scans, attempts to prevent<unk>  have been difficult. The dangers of repeated<unk>  have long been known for boxers and wrestlers; a form of CTE common in these two<unk> s, dementia pugilistica (DP), was first described in 1928. An awareness of the risks of<unk>  in other<unk> s began to grow in the 1990s, and especially in the mid-2000s, in both the medical and the professional<unk> s communities, as a result of studies of the brains of prematurely deceased American football players, who showed extremely high incidences of CTE (see<unk>  in American football). As of 2012, the four major professional<unk> s leagues in the United States and Canada included policies for managing<unk> risk.<unk> s-related<unk>  are generally analyzed by athletic training or medical staff on the sidelines using an evaluation tool for cognitive function known as the<unk> <unk> Assessment Tool (SCAT), a symptom severity checklist, and a balance test.
Concussions in sport
Concussions in rugby union
Suicide by jumping from height
Mushroom poisoning
Bad trip
Illness and injuries during spaceflight
Skin conditions in instrumental musicians
Bee sting