Preliminary data from a pilot study of retired professional English soccer players has found that, once their playing careers end, the chronic low-level head trauma they sustained from repetitive heading does not put them at greater risk of long-term cognitive decline than the general population.
The study, published in the British Journal of Medicine, suggests either that the short-term neurocognitive changes some studies have found are reversible or that heading may not be as harmful as commonly believed.
Reviewing data from questionnaires collected from 92 former members of four professional football clubs in the United Kingdom who completed a Test Your Memory (TYM) questionnaire, a self-assessed test of cognition, researchers from the Institute for Ageing and Health at Newcastle University and Newcastle-upon-Tyne Hospitals found that 10 scored less than the cut-off for their age and therefore screened positive for mild cognitive impairment (MCI), with 2 scoring well beneath the cut-off for possible dementia.
But comparing these results with the only large UK-based MCI prevalence study, lead author Simon Andrew Van Jones, MD and his colleagues, found there was no statistical difference between cognitive impairment among the sample of ex-professional footballers and a large sample of men in Wales, and the pattern held across all age groups over 65 divided into 5-year groups.
"Our findings counter a number of previous studies which have suggested that chronic subconcussive head injury in [soccer] may be a risk factor for accelerated cognitive deficit," writes Van Jones. "These suprising results are supported by a lack of any statistical difference in cognitive performance on the TYM test between players in positions with very minimal exposure to heading - goalkeepers - and those for whom heading the football is a frequent and unavoidable occupational hazard."
"This suggests that the short-term and medium-term cognitive decline caused by heading may be only transient," Van Jones said. "The discovery that an extended length of playing career did not significantly add to the risk of a positive screening may be seen as further evidence of this and supports previous studies which failed to find any significant neurological consequences of heading," he concluded.
Because of the relatively small sample size and potential for selection bias, the absence of detailed information on known risk factors such as previous concussions and drug and alcohol use, the study authors said future longitudinal studies of large numbers of professional football players were needed to support their findings.
Despite these limitations, however, they claimed it was "useful to note that players experiencing prolonged exposure to multiple head trauma continued to remain cognitively intact well into later life," including the two oldest respondents - 81 and 86 years old, respectively - who spent 13 years heading a heavy leather ball without any significant decline in their scores on the TYM.
"These results provide some evidence against the present thinking that head injury or concussion is chronically damaging to neurological health."
Study design criticized
Commenting on the study for MomsTEAM, Frank M. Webbe, Ph.D. Professor of Psychology, Florida Institute of Technology, and an expert on the subject of soccer heading, characterized its design limitations as "severe."
"Only 300 surveys were distributed, and these to active members of retired players associations. Less than half of the surveys were returned. The threat of self-selection of participants who are more cognitively able than than those who did not return the survey is huge," Webbe said.
"Moreover, the TYM instrument is only a screener, and does not have the capacity for any true diagnostic statement."
[For a comprehensive article discussing the research on soccer heading, click here.]
1. Van Jones SA, Breakley RW, Evans PJ. Heading in football, long-term cognitive decline and dementia: evidence from screening retired professional footballers. Br J Sports Med. 2014;48:159-161, doi:10.1136/bjsports-2013-092758.
2. Hancock P, Larner AJ. Test Your Memory Test: diagnostic utility in a memory clinic population. Int J Geriat. Psychiatry 2013;26:976-980. doi:10.1002/gps.2639.