Differences in White Matter Hyperintensities Among American Football Players

Older former American football players exhibited greater total, frontal, temporal, and parietal lobe white matter hypersensitivities compared to age-matched, asymptomatic, unexposed men, according to findings published in Alzheimer’s & Dementia.

White matter hypersensitivities correlated with worse executive functioning and verbal memory in former football players as evidenced by neuropsychological testing.

Since the presentation, risk factors, and etiologies of white matter hyperintensities among people exposed to repetitive head impacts are unknown, researchers sought to assess the burden and distribution of white matter hyperintensities, and their relationship with years of play, age of first exposure, and clinician function in former football players.

They recruited participants from the Diagnostics, Imaging, and Genetics Network for the Objective Study and Evaluation of Chronic Traumatic Encephalopathy (DIAGNOSE CTE) Research Project. They enrolled 120 former professional American football players, 60 collegiate football players, and 60 asymptomatic men without traumatic brain injuries (TBIs) or repetitive head injuries — all between the ages of 45 and 74 years. Only 53 asymptomatic individuals (mean age, 59.32 years; 62.3% White) and 149 former football players (mean age, 57.13 years; 63.8% White) completed the study.

Baseline evaluations collected information from a battery of neuropsychological tests, magnetic resonance imaging (MRIs), and self-reported measures of neuropsychiatric functioning among other procedures.

Of the 114 former football players, 83 (57.6%) demonstrated white matter hyperintensities in the frontal lobe, 41 (28.5%) in the temporal lobe, 79 (54.9%) in the parietal lobe, and 89 (61.8%) in the occipital lobe.

Former football players demonstrated greater total volume of white matter hyperintensities compared with asymptomatic, unexposed individuals (Unstandardized estimate [Est.] 0.65, 95% CI, 0.22-1.08; P <.01). Compared with asymptomatic individuals, all football players had greater white matter hyperintensities within the parietal (Est., 2.07; 95% CI, 0.90-3.24; P <.01) and temporal lobes (Est., 2.03; 95% CI, 0.67-3.39; P <.01), while no differences in the frontal or occipital lobes were observed.

However, separating the football players into older (age ≥60 years) and younger subgroups revealed that the older players — not the younger — had greater total, frontal, temporal, and parietal lobe white matter hypersensitivity volumes compared to asymptomatic individuals.

Additionally, the researchers observed no difference between the professional and the collegiate football players in the location or total volume of white matter hyperintensities.

The researchers calculated the volume of white matter hyperintensities using an automated lesion prediction algorithm. They discovered that greater total white matter hyperintensity volumes which correlated with older age (r = 0.50; P <.001) and higher revised Framingham Stroke Risk Profile (rFSRP) scores (r = 0.45; P <.001). They also found a correlation between age of first exposure to football and worse executive function only in older former football players compared with younger former football players.

“Older but not younger former football players had a great total, frontal, temporal, and parietal lobe white matter hyperintensity compared to same-age asymptomatic unexposed men,” the researchers stated. They concluded, “The causes of [white matter hyperintensities] are multifactorial and might have unique presentations, risk factors, and etiologies in the setting of aging and [repetitive head impacts] exposure from football.”

Study limitations include possible misclassification and false negatives which may have led to the underestimation of white matter hyperintensities, restriction of the study only to men and the experimental group only to American football players, limiting generalizability to women and other athletic populations, and the impact of health care disparities on the results.

Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.