Soccer heading and white matter microstructural changes: a two-year longitudinal cohort study.

Abstract

Soccer is played by over 265 million people worldwide, with repetitive head impacts from ball heading being common practice. However, the long-term neurological effects of such impacts on amateur players remain poorly understood. This two-year longitudinal cohort study examined whether cumulative soccer ball heading affects white matter microstructure and cognitive performance in adult amateur players from the New York City metropolitan area.The study followed 159 amateur soccer players (24.3% female, ages 18–53) who completed diffusion MRI scans and cognitive assessments at baseline and two-year follow-up. Heading exposure was quantified using the validated HeadCount-12 m questionnaire administered annually. Changes in DTI and NODDI parameters were analyzed across 10 white matter regions, alongside cognitive performance across six domains using the CogState battery.Participants were categorized by two-year heading exposure: low (n = 80, median 304 headers), medium (n = 39, median 808 headers), and high (n = 40, median 2,073 headers). After FDR correction across 70 tests (7 diffusion metrics × 10 white matter ROIs), one association exceeded the correction threshold. In the right middle fronto-orbital white matter, low-exposure players showed significant ODI decrease (mean change = -0.020, P < .001), whereas high-exposure players showed no significant change (mean change = -0.006, P = .16), yielding a significant group difference in covariate-adjusted analyses (β = 0.0132, 95% CI [0.005, 0.0214]; Cohen d = 0.58; P = .002). While no cognitive performance measures showed significant associations with heading after multiple comparisons correction, increased right middle fronto-orbital white matter orientation dispersion index correlated with declining working memory performance (β = -1.35; 95% CI [-2.45, -0.24]; P = .018). These findings provide the first longitudinal evidence linking soccer heading exposure to white matter microstructural changes, highlighting the need for continued assessment of long-term neurological consequences in young adult players.