Soccer players have a 62% higher risk of developing Alzheimer’s than the general population, according to a study of more than 6,000 Swedish first division players presented yesterday in The Lancet Public Health. Neurological damage is attributed to the accumulation of micro-lesions in the brain from repeatedly hitting the ball with the head.
The study did not find that soccer players are at increased risk of Parkinson’s or amyotrophic lateral sclerosis (ALS), which are also neurodegenerative diseases but have different causes than Alzheimer’s.
The list of footballers who have suffered from dementia includes legends like Kubala, Puskas, Gerd Müller or Bobby Charlton. But in an individual case it is impossible to know if football was the cause of the dementia or if they would also have suffered from dementia if they had not been footballers.
To clarify whether the relationship may be cause-effect, researchers from the Karolinska Institutet in Stockholm have analyzed medical data from 6,007 soccer players who have played in the Swedish first division since 1924 and compared them with those of 56,168 men from the general population. Diagnoses of neurological diseases, data on hospitalizations and outpatient consultations, drug prescriptions and death certificates have been analysed.
The results presented in The Lancet Public Health show that 8.2% of soccer players (one in twelve) have developed Alzheimer’s or other dementias. In the general population of men of the same age and from the same region, the percentage has been 5.1% (almost one in twenty).
The difference is equivalent to a 62% increased risk of developing dementia for footballers as a whole and rises to 67% for outfield players. For goalkeepers, on the other hand, no significant risk difference is observed with respect to the general population.
“Goalkeepers are exposed to the same environment and lifestyle as outfield players, but rarely head the ball,” Peter Ueda, the study’s first author, says by email. For the researcher, the difference between goalkeepers and field players indicates that “mild head injuries from heading the ball are the reason why soccer players have a higher risk” of dementia.
The Swedish study is the second to analyze the relationship between soccer and neurological damage in a large sample of soccer players. The former, based on 7,676 retired Scottish footballers, found an even higher relationship. According to data published in 2019 in The New England Journal of Medicine , former Scottish professional footballers have a 3.5 times higher risk of neurodegenerative diseases than the general population.
The difference between the results of Sweden and those of Scotland may be due to the fact that each culture has its own style of play and headers are more frequent in Scotland, the researchers from the Karolinska Institute point out. Other factors that may influence are different training routines or a lower frequency of matches in Sweden, where soccer did not become professional until the late 1960s.
As playing styles and ball design have evolved, “it is not clear that the results [of our study] can be generalized to today’s soccer players,” the authors of the research warn in The Lancet Public Health. “Although the regulation of ball weights has not changed since the late 19th century, there has been a gradual replacement of leather balls with synthetic materials that do not absorb water,” so they do not gain weight when wet.
On the contrary, the fact that professional soccer players play more games now than in the past, and that they play more frequently from a younger age, may contribute to increasing the risk.
It’s also not clear to what extent data from a sample of professional men can be generalized to women or amateur soccer players, the researchers add.
