Retired professional ruby players were more likely to be depressed, anxious and irritable compared to amateur players or non-contact athletes, new research has found.
The former top players who took part in the study had suffered more concussions on the pitch than those in the other groups, and the researchers believe this could be linked to worse mental health later in life.
Those who had suffered five or more concussions were almost twice as likely to report signs of depression, anxiety and irritability compared with players with fewer concussions.
These players were also more likely to struggle with feelings of hidden anger.
Signs of depression and irritability were also more common in rugby players who had suffered three or more concussions in their playing career.
Half the players with three or more concussions experienced these indicators of poor mental health, compared to a third of those who had suffered less than three concussions.
The retired professionals, who played union or league in the UK, were compared to amateur rugby players and non-contact athletes, such as cricketers and runners.
Scientists say more research is needed to explore if there is a direct neurobiological connection between repeated concussions and longer term psychological health, and to investigate possible links with the development of neurodegenerative disease.
The study is published in Sports Medicine, and is part of the UK Rugby Health Project, led by Durham University and involving researchers in New Zealand and Australia.
Dr Karen Hind, from Durham University's Department of Sport and Exercise Sciences, said: "Our study shows that elite level rugby players disclosed more adverse mental health issues following retirement from the sport, compared to those who had played amateur level rugby, or a non-contact sport.
“This was particularly the case for those players who had experienced three or more concussions.
“These findings add to a growing body of evidence that can inform strategies to support player welfare and they shed further light on risks of repeated concussions.”
The researchers acknowledged that if a player was forced into retirement due to injury it could play a role in their well-being after hanging up their boots.
The study also found that former professional rugby players were more likely to suffer disturbed sleep than the others.
Ex-Wales forward Alix Popham, who was not part of the study, was diagnosed with probable chronic traumatic encephalopathy (CTE) and early onset dementia last year as a result of brain injuries he suffered on the pitch.
The 42-year-old Grand Slam winner said: “The evidence from this research correlates with our lived experience from talking to and supporting members of the rugby family currently struggling following their professional careers.”
Concussion has become a major topic for study in other sports, with repeatedly heading footballs being linked to dementia in former players.
Dr Judith Gates co-founded the charity Head for Change after her husband Bill developed a degenerative brain injury after playing at the back for Middlesbrough FC.
She said: “This paper adds further evidence as to the strong associative links between sports-related traumatic brain injuries and subsequent neurodegenerative disease.
“The evidence is mounting.”