Neuroscience researchers from Boston University recently confirmed that former NFL player Dave Duerson suffered from chronic traumatic encephalopathy (CTE), a serious degenerative brain disease. Duerson committed suicide in February, leaving behind a note (and sending a text message) for his family, asking that his brain be donated to the CSTE Brain Bank, also known as the NFL Brain Bank.

Duerson is the latest example of several retired professional sports figures who have met early deaths due in part to CTE. There are a wide range of fervently held opinions regarding concussions on the playing field. Many comments accurately point out that hundreds of thousands of players (at school and collegiate levels) probably have been exposed to a concussion over the past several decades, with most players remaining cognitively intact over the long term.

So why the apparent disconnect between the rash of CTE symptoms in the NFL (and the NHL and the boxing world), and the relative lack of symptoms in the non-professional sporting world? The answer most probably lies with repetitive head impact incurred by professional athletes in these sports.