Playing Football Linked to Higher Parkinson's Risk

Megan Brooks

August 15, 2023

New research suggests a potential link between playing tackle football and an increased risk of developing parkinsonism or Parkinson's disease (PD).

In a cross-sectional study of older men, former tackle football players had a 61% higher likelihood of reporting a diagnosis of parkinsonism or PD, compared with men who played non-football sports.

Longer duration of football participation and higher level of play (college and professional) were associated with higher risk.

Lead researcher Michael L. Alosco, PhD, director, Boston University Alzheimer's Disease Research Center, said it's important to note that the findings are from a cohort of men "enriched" for having PD.

"These are people who are likely already concerned for or at risk for having this disease. We don't yet know how our findings translate to the general population," Alosco told Medscape Medical News.

The study was published online August 11 in JAMA Network Open.

Repetitive Head Impacts

Dating back to the 1920s, PD and parkinsonism ― an umbrella term that refers to motor symptoms associated with PD and other conditions ― have long been described in boxers who suffer repetitive head impacts.

Multiple studies have linked tackle football with progressive brain diseases such as chronic traumatic encephalopathy. However, few studies have investigated the association between participation in football and PD.

For their study, Alosco and colleagues leveraged data from Fox Insight, a longitudinal online study of some people with and some without PD that is sponsored by the Michael J. Fox Foundation for Parkinson's Research.

They focused their analyses on 1875 men (mean age, 67 years) who reported playing any organized sport. As noted, the cohort was enriched for parkinsonism or PD. A total of 1602 (85%) had received a diagnosis of parkinsonism/PD, and 273 had not.

Altogether, 729 men had a history of playing tackle football, and 1146 men played non-football sports (control group). Among the football players, 82% played at youth sports or at the high school level; 17% played at the college level; and fewer than 1% played at the pro or semi-pro level.

Among the football players, 648 (89%) reported a parkinsonism/PD diagnosis.

A history of playing football was associated with higher odds of reporting a parkinsonism/PD diagnosis (odds ratio [OR] 1.61; 95% CI, 1.19 – 2.17) after accounting for age, education level, history of diabetes and heart disease, body mass index (BMI), traumatic brain injury with loss of consciousness, and family history of PD.

Football players who had longer careers and who played at higher levels of competition were at increased risk of having parkinsonism or PD.

Playing one to four seasons yielded an OR 1.39 (95% CI, 0.98 – 1.98). The OR was 2.18 (95% CI, 1.36 – 3.49) for playing five or more seasons.

Football players who competed at the college or professional level had nearly triple the odds of reporting a parkinsonism/PD diagnosis (OR, 2.93; 95% CI, 1.28 – 6.73) compared with athletes who played at the youth or high school level.

Age at first exposure to football was not associated with a parkinsonism/PD diagnosis.

The researchers caution that this was a convenience sample of mostly White people, and the sample was enriched for having PD ― factors that limit the generalizability of the findings.

Also, diagnosis of PD was self-reported by participants through online assessments, and objective in-person evaluations were not conducted.

Unequivocal Link?

"This is among the first and largest to look at the relationship between football and having a diagnosis of PD in a large cohort of people from the Fox Insight online study," Alosco told Medscape Medical News.

He cautioned that "not all people who play football will develop later-life neurological problems. That being said, the study adds to the accumulating evidence that suggests playing football is one risk factor for the development of later-life brain diseases.

"This represents an opportunity to educate the communities on the potential risks of playing football (short and long-term), including what we know and what we don't know, so that people can make informed decisions on participating in tackle football and develop additional ways to mitigate risk," Alosco said.

Commenting on this research for Medscape Medical News, Shaheen Lakhan, MD, PhD, a neurologist and researcher from Boston, Massachusetts, said, "The emerging body of research leaves little doubt that engaging in football raises the risk of developing Parkinson's disease and parkinsonism.

"This progressive line of investigation serves to enhance our understanding, unequivocally demonstrating that even participation in amateur football, including at the youth and high school levels, constitutes a significant risk factor for the onset of Parkinson's disease," said Lakhan, who was not involved in the study.

However, he said it's "crucial to underscore that the statistics reveal a notable distinction: individuals who have a history of college or professional football play face odds nearly three times higher of receiving a diagnosis of parkinsonism or Parkinson's disease when compared to their counterparts who engaged in football during their youth or high-school years.

"Ultimately, determinations regarding involvement in sports should be a collaborative endeavour involving parents, young athletes, and healthcare providers. It is incumbent upon physicians to equip parents and youth with a comprehensive comprehension of the potential risks and rewards inherent in football participation," Lakhan said.

He added, though, that there are multifaceted advantages to playing football. "This pursuit nurtures cardiovascular well-being, fosters invaluable social interactions, cultivates teamwork, instills discipline through regimented routines, and hones a spectrum of physical proficiencies," Lakhan said.

"It's worth noting that a constellation of alternative sports, including track and field, swimming, soccer, baseball, and tennis, can be cogently discussed as substitutes, all while preserving the manifold benefits of athletic engagement," Lakhan added.

The Fox Insight Study is funded by the Michael J. Fox Foundation for Parkinson's Research. The study was conducted in collaboration with the Michael J. Fox Foundation for Parkinson's Research, the sponsor of the Fox Insight study, which collected and aggregated data used in the study. It was also supported by the National Institute of Neurological Disorders and Stroke. Alosco received grants from the National Institutes of Health during the conduct of the study, an honorarium from the Michael J. Fox Foundation for work unrelated to the study, and royalties from Oxford University Press outside the submitted work. Lakhan has disclsoed no relevant financial relationships.

JAMA Netw Open. Published online August 11, 2023. Full text

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