Cognitive function among former professional male soccer players, the HEADING study

BackgroundThe HEalth and Ageing Data IN the Game of football (HEADING) study assessed the associations between exposure to heading a football, other impacts to the head, and concussions, with cognitive function, among former professional soccer players in England. MethodsRecruitment of former male professional soccer players aged 50+ years was conducted through the English Professional Footballers Association. Cumulative exposure to heading and other impacts to the head was estimated from the playing history questionnaire. Concussion was self-reported and assessed with the BRAIN-Q tool. The primary outcome was cognitive function measured with the Preclinical Alzheimer Cognitive Composite (PACC). FindingsData for a total of 199 males were available for analysis. No overall association was found between heading and/or other impacts to the head and cognitive function. Amongst forwards only, those in the fourth (highest) quartile of exposure to other impacts to the head had a significantly lower PACC score compared to those in the first quartile (* = -0.65, 95% C.I. -1.23, -0.07). For all players, self-reported concussions were associated with slightly lower cognitive function (* = -0.01; 95% C.I. -0.01, -0.001). InterpretationThis study generally does not support an association between exposure to heading a football and poorer cognitive function among former male professional players. However, an association between the number of concussions sustained and poorer cognitive function was present, although the effect size is relatively small. FundingThis study was funded with a grant of the Drake Foundation to the London School of Hygiene and Tropical Medicine. Research in context Evidence before this studyThere is increasing evidence for an association between sport-related concussion and poorer cognitive function later in life, in former athletes. In soccer, heading the ball is a common event, particularly for outfield players, and involves repetitive sub-concussive impacts. The association between exposure to heading and cognitive function later in life is not consistent in the literature. Added value of this studyThis study is the first to provide appropriately modelled exposure estimates of both heading the ball and other impacts to the head among soccer players. Our findings do not support an association between heading and poorer cognitive function later in life. However they do suggest an association between concussion and poorer cognitive function among soccer players, although the size of the effect is relatively small. Other impacts to the head, such as head-to-head collisions, that did not result in the clinical features of concussions were also shown to be associated with poorer cognitive function, but only among forwards. Implication of the available evidenceThese findings support a continuous focus on the prevention of concussion in all sports, including soccer, whilst the consequences of repeated exposure to head impacts need to be further explored. Methodologically, it would be advisable to harmonise the tools developed to estimate cumulative exposures to heading, to other head impacts, and to sport-related concussion, to increase comparability of results across studies, thus enabling a sound synthesis of the evidence.