Objective: To assess whether high school football played between 1946 and 1956, when headgear was less protective than today, was associated with development of neurodegenerative diseases later in life. Methods: All male students who played football from 1946 to 1956 in the high schools of Rochester, Minnesota, plus a non-football-playing referent group of male students in the band, glee club, or choir were identified. Using the records-linkage system of the Rochester Epidemiology Project, we reviewed (from October 31, 2010, to March 30, 2011 all available medical records to assess later development of dementia, Parkinson disease (PD), or amyotrophic lateral sclerosis (ALS). We also compared the frequency of dementia, PD, or ALS with incidence data from the general population of Olmsted County, Minnesota. Results: We found no increased risk of dementia, PD, or ALS among the 438 football players compared with the 140 non-football-playing male classmates. Parkinson disease and ALS were slightly less frequent in the football group, whereas dementia was slightly more frequent, but not significantly so. When we compared these results with the expected incidence rates in the general population, only PD was significantly increased; however, this was true for both groups, with a larger risk ratio in the non-football group. Conclusion: Our findings suggest that high school students who played American football from 1946 to 1956 did not have an increased risk of later developing dementia, PD, or ALS compared with non-football-playing high school males, despite poorer equipment and less regard for concussions compared with today and no rules prohibiting head-first tackling (spearing). M ultiple concussive head injuries incurred in sporting activities previously have been associated with progressive neurodegenerative disease later in life. Initially, it was reported in boxers (dementia pugilistica), 1 but an evolving literature now suggests that this risk extends to other sports in which concussions are common. The term chronic traumatic encephalopathy (CTE) has been used to define this condition, with dementia being the primary delayed outcome.2 Besides fighting sports, American football, soccer, and hockey predispose players to head trauma and have been implicated in the later development of CTE. 3,4 Moreover, head trauma and sport-related trauma have been reported as risk factors for development of Parkinson disease (PD), 5 dementia, 6 and amyotrophic lateral sclerosis (ALS). 7,8 Although repeated concussive head trauma is a purported risk factor for later neurodegenerative disease, few studies have evaluated long-term risks in a cohort of athletes participating in a sport that is often associated with concussions.9 American football as played several decades ago often put participants at risk for concussion, which at the time was commonly disregarded ("bell rung"); moreover, the protective headgear of that era was marginally protective against concussions (Figure 1). We chose to analyze the long-term medical ou...