The REPIMPACT study, published in JAMA Network Open in June 2026, found no short-term neurological changes in adolescent male soccer players. The study observed no differences in brain structure, function, or cognitive health in soccer players compared to noncontact sport athletes over the short term.

The longitudinal, prospective, multicenter cohort study was conducted across three European sites: Munich, Germany; Leuven, Belgium; and Oslo, Norway. The study sample included 129 male athletes aged 14 to 16 years. Eighty-two academy-level soccer players who practiced at least three times weekly participated. The cohort also included 47 age-matched controls who practiced noncontact sports such as swimming, athletics, cycling, and racket sports. Participants with a history of physician-diagnosed concussions were excluded from the study.

Study data collection occurred in three phases: preseason, postseason, and two months following the end of the season. Researchers evaluated cognition and balance using computerized testing (Cogstate) and balance boards. Neuroimaging was captured with multimodal magnetic resonance imaging. The study also analyzed brain biochemistry and blood biomarkers, including periventricular white matter total N-acetylaspartate (tNAA) concentrations, plasma levels of glial fibrillary acidic protein (GFAP), and neurofilament light chain (NfL). Heading exposure was tracked using structured questionnaires.

Soccer players showed no differences in cognitive capabilities, behavioral scales, or balance trajectories when compared to the control cohort. Structural and functional neuroimaging metrics, including cortical thickness, total gray or white matter volume, white-matter microstructure, and default mode network connectivity, did not differ between soccer and noncontact group participants over time. The study also found no correlation or association between self-reported heading volume and any neurological metric in the soccer group.

Soccer players exhibited higher concentrations of tNAA, GFAP, and NfL than controls at baseline and preseason. tNAA levels converged between groups over the season, as they declined in players and rose in controls. GFAP and NfL levels remained consistently higher in the soccer cohort throughout the season, although they remained within the normal physiological range for this age group.

The researchers, citing study authors, stated that the study was limited by its reliance on self-reported exposure and an exclusively male cohort. Other limitations included the observational, nonrandomized design, potential residual confounding, limited generalizability beyond European male academy settings, exclusion of athletes with prior physician-diagnosed concussion, and possible underpowering to detect small effects. The study authors emphasized the need for large-scale, multiyear studies to establish the chronic effects of soccer on neurological health.