Compared to the general population, male professional footballers are at higher risk for neurodegenerative disease, especially if they are in non-goalie positions and / or have careers of more than 15 years, according to study results published in JAMA Neurology.
The risk of mortality from neurodegenerative diseases is higher among former football professionals compared to the general population. However, the identification of the factors associated with this increased risk for this particular group has remained unknown.
The British researchers identified male former professional football players from Scotland born between 1900 and 1977 using the pre-war Scottish league player record, version 2 and the post-war Scottish league player record, version 6.
Using population-based data for linking health records, the risk of neurodegenerative diseases among former soccer players (n = 7676) was examined in comparison with a corresponding control group of the general population (n = 23,028). The total data included 1,812,722 person-years of follow-up (mean total follow-up, 18 years).
During the follow-up period, approximately 5.0% of the former football professionals (n = 386) and 1.6% of the comparison population (n = 366) were diagnosed with a neurodegenerative disease (hazard ratio [HR], 3.66; 95% CI 2.88-4.65; P <.001).
While the risk of neurodegenerative disease was higher in goalkeepers than in the matched control group, there was no significant difference between the two groups (HR 1.83; 95% CI 0.93-3.60; P = 0.08). However, field players had a significantly higher risk of neurodegenerative diseases than comparable controls (HR, 3.83; 95% CI, 3.11-4.73; P <0.001), even after adjusting for deaths due to non-neurodegenerative diseases. Field players also had a higher risk of neurodegenerative diseases than goalkeepers (odds ratio [OR], 2.22; 95% Cl, 1.35-3.64; P = 0.002)).
In addition, the risk of neurodegenerative disease was lower for forward positions (HR 2.79; 95% CI 2.06–3.78; P <0.001) and higher for defenders (HR 4.98; 95% CI 3.18–7 .79; P <.001; OR 1.52; 95% CI 1.12-2.07; P = 0.008).
In the cohort, the average career of a professional field soccer player was 8.6 years. Careers typically ranged between players between the ages of 20.0 and 28.5 years. The risk of neurodegenerative diseases increased with increasing length of employment (P = 0.01). The risk of neurodegenerative disease was significantly lower in players with a short career compared to comparable controls (HR 2.26; 95% CI 1.51-3.37; P <0.001). In contrast, the risk increased among players with longer careers (HR 5.20; 95% CI 3.17-8.51; P <0.001).
Limitations of this study were the lack of data on the participation of soccer players in other contact sports as well as the lack of data on the extended participation of the players in non-professional soccer beyond the retirement age. In addition, it is likely that some people in the general population control group did not play football professionally, which can also be linked to an increased risk of neurodegenerative diseases.
While the researchers in this retrospective study suggest that more research is needed to investigate the risks associated with amateur football, they add that “the application of a precautionary principle to reduce the risk of neurodegenerative disease by reducing exposure to traumatic brain injury and Head butts in soccer and “broader sports might be recommended.”
Disclosure: Some study authors declared their affiliations. For a full list of the details, see the original article.
Russell ER, Mackay DF, Stewart K, MacLean JA, et al. Association of field position and career length with the risk of a neurodegenerative disease in male former professional footballers. JAMA Neurol. Published online August 2, 2021. doi: 10.1001 / jamaneurol.2021.2403