Another bit coming from the Frontline program “League of Denial,” which looked at the impact of brain injuries stemming from American football:

“The nation’s largest youth football program, Pop Warner, saw its participation rate drop 9.5 percent from 2010-2012, according to an Outside the Lines report by League of Denial authors Steve Fainaru and Mark Fainaru-Wada. ‘Pop Warner lost 23,612 players, thought to be the largest two-year decline since the organization began keeping statistics decades ago,’ the report found. ‘Pop Warner officials said they believe several factors played a role in the decline, including the trend of youngsters focusing on one sport. But the organization’s chief medical officer, Dr. Julian Bailes, cited concerns about head injuries as ‘the No. 1 cause.’”