Post-concussion syndrome
About 10% of people with PCS develop sensitivity to light or noise, about 5% experience a decreased sense of taste or smell, and about 14% report blurred vision. People may also have double vision or ringing in the ears, also called tinnitus. PCS may cause insomnia, fatigue, or other problems with sleep.
American football
Repeated concussions (and possibly sub-concussive head impacts) can increase a person's risk in later life for CTE (chronic traumatic encephalopathy) and mental health issues such as dementia, Parkinson's disease, and depression. Concussions are often caused by helmet-to-helmet or upper-body contact between opposing players, although helmets have prevented more serious injuries such as skull fractures. Various programs are aiming to reduce concussions by reducing the frequency of helmet-to-helmet hits; USA Football's "Heads Up Football" program is aiming to reduce concussions in youth football by teaching coaches and players about the signs of a concussion, the proper way to wear football equipment and ensure it fits, and proper tackling methods that avoid helmet-to-helmet contact. However, a study in the "Orthopaedic Journal of Sports Medicine" found that Heads Up Football was ineffective; the same study noted that more extensive reforms implemented by Pop Warner Little Scholars and its member teams were effective in significantly reducing concussion rates.