A major new study has found that concussions in amateur sport are not linked to greater long-term risks of cognitive decline – and that playing sport may potentially have a “protective” effect on the brain.

The surprise results – published in the Journal of Neurology, Neurosurgery and Psychiatry – were based on analysing lifetime concussion histories from more than 15,000 participants aged between 50 and 90, making it the largest study of its kind.

Notably, researchers from the University of Exeter, UNSW Sydney, the University of Oxford and Harvard University, also found that people who reported sports‑related concussions actually had a mar­ginally better cognitive performance than those who reported no con­cussions.

One of the paper’s authors, Prof Vanessa Raymont from the ­University of Oxford, said the ­findings could have policy implications for contact sports.

“This study suggests that there could be long-term benefits from sport which could outweigh any nega­tive effects of concussions, which could have important implications for policy decisions around contact sport participation,” she said. “It may also be that non-sports-related head injuries lead to greater brain damage than sports-related concussions.”

However, the authors stressed that their findings did not apply to concussions in professional sport, which “tend to be more frequent, debili­tating and severe”.

Of the 15,214 participants in the study, 39.5% reported at least one concussion and 3.2% at least one moderate-severe concussion. Researchers then compared cognitive function among individuals with zero, one, two and three or more sports-related concussions (SRCS) to those with zero, one, two and three or more non-sports-related concussions from falls, car accidents, assaults and other causes. The SRC group showed 4.5 percentile rank ­better working memory than those who had not experienced an SRC as well as a 7.9% better reasoning capacity than those without concussions.

The results were broadly welcomed by professor John Fairclough of Progressive Rugby. “This retrospective study supports the assertion that compared to the elite game, the community game is relatively safe, and concussion and long-term neurological risk is in the main outweighed by the physical, mental and social benefits enjoyed,” he said.

“All contact sports pose a risk, but with continued steps to educate, mitigate risk and ensure concussion protocols are strictly observed we have always maintained the community game can continue to become even safer and more sustainable.”

Fairclough warned, however, that there were still “legitimate concerns about children participating in ­contact sports” and said that more studies were needed “to establish the risk around juveniles being exposed to contact sport while their brain is undergoing key periods of development”.

He said: “It is also important to note that this study was not set up to and cannot determine the risk to professional players who are subjected to a far higher number and frequency of impacts to which degenerative brain diseases including chronic traumatic encephalopathy (CTE) are associated.”

Luke Griggs, the chief executive of the brain injury charity Headway, was more cautious in his response. “This study supports some established principles relating to concussion,” he said. “We know, for example, that the majority of single-incident concussions will have no lasting effects on individuals.

“However, we have to be cautious in ensuring this data is not misinterpreted. There is a fundamental risk associated with any inference that sport and cardiovascular exercise can eliminate the impact of concussion.”