More Years of U.S. Football Linked to Worse Cognitive, Psychiatric Outcomes in Later Life

Somewhere north of 28 million men in the United States played organised tackle football at some point in their lives. Most of them stopped after high school, hung up the pads, moved on. They coach their kids’ teams now, perhaps, or just watch from the sofa on Sundays. But a study published today in JAMA Network Open suggests that what happened on those fields, sometimes decades ago, may still be quietly shaping how their brains work.

The research, led by Michael Alosco at Boston University’s CTE Center, tracked cognitive and neuropsychiatric outcomes across 3,970 former players aged 40 and older. It is one of the largest studies to date that includes men who played at every level, from youth leagues through to the professional ranks. And the pattern it found was consistent, almost unsettlingly so: the more years a man spent playing football, and the higher the level he reached, the worse he tended to score on tests of memory, executive function, and mood.

That gradient matters. Previous work in this area has mostly focused on elite professionals, former NFL players whose decades of collisions make them obvious candidates for brain injury research. This study deliberately cast a wider net through its Head Impact & Trauma Surveillance Study, or HITSS, an online longitudinal project built on top of the University of California, San Francisco’s Brain Health Registry. The roughly 4,000 participants weren’t all gridiron stars. About 46 per cent never played beyond high school.

In a substudy, the team compared 661 former players against 282 men matched for age, race, education and ethnicity who reported no history of repetitive head impacts. The players performed worse across the board. They made more errors on a computerised memory test, reported greater everyday cognitive concerns, and scored higher on a depression scale. The differences were statistically significant on every measure.

But it’s the dose-response relationship within the football cohort that really stands out. Professional players, who averaged roughly 14 years on the field, had the worst outcomes. College players (about ten years of play) fell in the middle. Those who stopped after high school or youth football, with around six years of exposure, fared best, though they still showed measurable differences compared with the non-football controls.

The numbers on depression are particularly striking. Former professionals had 2.21 times the odds of clinically meaningful depressive symptoms compared with men whose highest level was high school or youth. College players sat at 1.42 times the odds. Each additional year of play was associated with a small but significant uptick in depression scores, problems with behavioural regulation, and subjective cognitive complaints.

What the study did not find is perhaps just as telling. Position didn’t seem to matter; linemen, who absorb the most frequent sub-concussive blows, showed no worse outcomes than players at other positions. And the age at which someone first started playing football had no significant association with any of the measures. That second finding runs counter to a strand of earlier research suggesting that younger brains might be more vulnerable to repetitive impacts, though the authors note their sample skewed younger (mean age 55) and relatively healthy, which could mask effects that emerge later.

There are caveats worth flagging. This is a cross-sectional study, not a longitudinal one, so it can’t prove that football caused the cognitive and psychiatric differences it observed. The participants were overwhelmingly white (81 per cent), highly educated (85 per cent held at least a four-year degree), and digitally literate enough to complete an online battery of tests, which hardly reflects the demographics of American football more broadly. Selection bias is a real concern; men who are already experiencing symptoms might be more motivated to sign up for a study about brain health after football.

Still, the consistency of the dose-response pattern across multiple independent measures is hard to dismiss. The findings align with autopsy research that has shown a similar gradient between duration and level of play and the severity of chronic traumatic encephalopathy, or CTE. What this study adds is evidence from living people, assessed with standardised tools, across all tiers of the sport.

For the millions of men who played a few seasons in their teens and then got on with the rest of their lives, the results offer some cautious reassurance. The effects at the lower end of the exposure spectrum, while statistically detectable, were modest. It’s at the upper end, among those who played for a decade or more, that the associations become more worrying. And for clinicians trying to work out whether a former player’s cognitive complaints might be connected to his sporting history, the study offers a practical framework: years played and level reached could help guide that conversation.

What it can’t tell you is whether any individual man is at risk. The authors are clear on that point. Genetics, medical history, social determinants of health, all of these likely interact with head impact exposure in ways this study wasn’t designed to untangle. The patterns are there in the aggregate. The question of what they mean for any one person, sitting in a doctor’s office at 60, wondering why he keeps losing his keys, remains stubbornly unanswered.

Study link: https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2845602

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