Former Springbok scrum-half Joost van der Westhuizen believes there may be a link between his rugby career and the motor neurone disease he was diagnosed with in 2011.
"It's not fair to say that rugby might be the cause, but there might be a link," he told BBC Radio 5 live.
"I went to Boston to take part in research. We have to wait and see."
When asked if he had suffered concussions that may have damaged his brain during his career, Van der Westhuizen replied: "I broke my nose 16 times, that should say enough."
No firm link has been established between sports involving high-speed collisions and high incidences of concussion - such as rugby union - and motor neurone disease.
Van der Westhuizen, who scored 38 tries in 89 Tests and was part of the Springbok team that won the 1995 World Cup on home soil, has been in the United Kingdom raising awareness about the disease and his J9 Foundation.
As part of his trip he visited England's training camp, where he posed for photographs with the squad's scrum-halves, and the Eagle Wood Neurological Care Centre in Peterborough, where a fundraising dinner was hosted by former British and Irish Lions winger John Bentley.
"The support I have had from the UK is amazing," added Van der Westhuizen.
"Although my body is failing me, my brain is 100%. I am still alive and well and I am creating memories everywhere I go.
"There is nothing you can do about the past, although it was fun. There is a lot I can do about the future though and I am still having fun.
"I have been around the world and seen a lot. I am confident that we will have a cure in five years and that gives me hope."
You can hear the rest of Joost van der Westhuizen's interview on 5 live Rugby from 20:00 GMT on Thursday 13 November.