Higher rates of dementia among former professional footballers are not driven by “lifestyle factors” such as smoking or obesity, a study has found.

The FIELD study at the University of Glasgow is investigating potential links between dementia and head impacts in sport.

Researchers found rates of dementia “risk factors”, such as smoking, depression, alcohol-related disorders and obesity, were similar or lower among former players than in the general public.

The study, which analysed health records from 11,984 former players and a “matched” control of 35,952 members of the public, also found the contribution of these factors to dementia outcomes was “notably lower” in former players than in the general population.

The priority for neurodegenerative disease risk mitigation among contact sports athletes should continue to focus on the reduction, if not removal, of exposure to repetitive head impacts and traumatic brain injury

Professor Willie Stewart, the consultant neuropathologist leading the FIELD study, said the findings highlighted the importance of reducing or removing exposure to head impacts in sport.

“Our latest results suggest the relationship between higher rates of neurodegenerative disease among former professional footballers is not driven by those wider general health and lifestyle factors, widely recognised as dementia risk factors,” he said.

“As such, while interventions to address general health and lifestyle risk factors should remain recommended, the priority for neurodegenerative disease risk mitigation among contact sports athletes should continue to focus on the reduction, if not removal, of exposure to repetitive head impacts and traumatic brain injury, wherever practical.”

The findings build on previous FIELD study research showing higher rates of neurodegenerative disease among former professional footballers.

In 2019 the study found former players were three and a half times more likely to die from neurodegenerative disease than the general public.

In 2021 researchers also identified a direct association between the length of a player’s career and their risk of developing dementia, with those with the longest careers seeing a fivefold increase in the risk of the neurodegenerative disease.

The study, titled Influence of health and lifestyle factors on dementia risk among former professional soccer players, was published in JAMA Network Open.

It was funded by the Football Association and the Professional Footballers Association, the National Institutes of Health and the Medical Research Council.