High-magnitude headers are not associated with structural and functional brain changes in active high-level football...

To date, consistent evidence for consequences of heading in football (soccer) on the structure and function of the brain is lacking, but first studies indicate a potential effect of specific high-magnitude headers. The purpose of this longitudinal, prospective study was to investigate whether potential structural and/or functional alterations within the brain were associated with (high-magnitude) heading.

3T MRI sequences were obtained from active high-level male players before and after an observation period of 17.2 months (median). Cortical thickness and grey matter (GM) volume were investigated on a whole-brain level. Functional connectivity (FC) was analysed in the default mode network (DMN) and salience network (SN). During the observation period, each training and each match was videotaped and evaluated regarding the heading exposure. Significant structural and functional findings were subsequently correlated with specific header characteristics.

14 included participants (mean age: 20.36±3.34 years) played 5822 headers. GM volume remained unchanged, whereas cortical thickness decreased minimally from pre-measurement to post-measurement in a left precentral region (mean change: 0.048±0.128 mm; clusterwise p=0.0416). Within the SN, FC increased in one cluster (false discovery rate corrected p=0.026). FC remained stable within the DMN and between DMN and SN. Change from pre-measurement to post-measurement for the significant results did not correlate with heading variables.

Our findings may indicate no cumulative effect of heading during the observation period. As these results contrast with cross-sectional findings, more longitudinal, prospective studies with a greater sample size are urgently needed to understand potential heading effects.