He understands that he'll die without knowing the full impact of those concussions, but hopes his decision will help future generations of athletes.
Valentine will get to see Chris Nowinski for the first time later this month, on the sidelines of a meeting that the American concussion expert is having with officials and players from the Australian Football League in Melbourne Nov. 18-19.
Nowinski, a Harvard graduate and former wrestler, is a co-director of the Center for the Study of Traumatic Encephalopathy at Boston University, otherwise known as the "Brain Bank." It is one of the leading research groups in the world on the effects concussions are having on athletes, highlighted by recent cases in the U.S. involving retired players from the National Football League.
Valentine, one of nearly 200 athletes who have committed to donating their brains to the Boston researchers for post-mortem investigations, has noticed how concussions have taken a toll on him.
Only 37, Valentine's short-term memory is terrible. Each night, he puts his keys and wallet in the same place in his home in Townsville on Australia's tropical north coast. And each morning, he needs help trying to find them.
He has a small landscaping business and remains involved in rugby league as a coach, but finds his lack of memory affecting his livelihood. He often forgets to return calls from existing or potential clients.
"It is getting really bad. You can tell me something and 10 minutes later I have no idea what you're talking about," he says. "It is something I just have to learn to live with."
The only way to confirm Chronic Traumatic Encephalopathy (CTE) is by examining brains after death, and Valentine has no issue with that.
"There's a lot of stuff you can't determine until you are dead. I'm not going to need (the brain) so why not?" Valentine told The Associated Press in a telephone interview. "When I read what was happening in America, the research that Chris was doing, I didn't hesitate."
Valentine played 36 games for the North Queensland Cowboys in Australia's top-flight National Rugby League competition, coming up against some of the highest-profile players in the extremely physical, rough-and-tumble game.
Things have improved marginally in Australian contact sports since injuries forced Valentine to retire as a player in 2003. Most of the collision sports have put procedures in place for when a player sustains a head knock during a game, ranging from sideline assessments from qualified medical staff to enforceable time out of the game.
But it's not all good news. Several club doctors in the NRL quit this year, saying regulations for concussions due to be put into place for the 2014 season don't go far enough. Valentine, who has never heard from the NRL over his concussion issues, agrees.
For one, he thinks any player suspected of being knocked unconscious should be automatically withheld at least for the remainder of that game. He cited boxing as an example, saying concussions meant a minimum 28 days on the sidelines.
"Why in all contact sports, do we not have ... a similar set time frame? We are talking about the brain ... one of the vitally important organs we have," he said.
Nowinski, a former tackle at Harvard who has had several concussions, was incredulous that Valentine had suffered seven concussions in such a short span. Nowinksi himself had six concussions in the last five years of playing.
"In a decade of advocacy, I have never heard of a professional American athlete having seven medically diagnosed concussions in 18 months, not even in the darkest day of concussion awareness," Nowinski told AP in an email response to questions.
Nowinski's trip to Australia - coinciding with his honeymoon - will see him speak to the Australian Rules football players association. He met Ian Prendergast, general manager of player relations for the AFL Players Association, about 18 months ago and the two have stayed in touch.
"I see this as an opportunity to share with Australian sports leadership the recent U.S. experience," he says. "My personal goals include sharing with the players my experience so that they may make more informed decisions about how they play, as well as building (a) relationship for future research collaborations. I gave the same presentation to the Rugby Players Association in England two weeks ago and it was a good experience."
Nowinski has only heard second hand how Australian sport is dealing with the concussion issue, but feels it needs to improve.
"In general, I think organizations are taking positive steps," he said, "but they will have to continue to work to change the culture and get policies in line with best practices."
Concussions are never far from the news, and not only in high-contact sports. South Africa cricket captain Graeme Smith recently was ruled out of the remainder of South Africa's limited-overs series against Pakistan with post-concussion syndrome following delayed symptoms of blurred vision and dizziness a week after he was hit on the head by a bouncing delivery.
In London, Tottenham faced criticism from soccer's international governing body, players' unions and medical experts over the club's handling of goalkeeper Hugo Lloris' head injury during a Premier League match against Everton. Lloris was allowed to continue playing after being briefly knocked unconscious.
Nowinski hopes that continuing a high level of media exposure of sports concussions continues.
"The research coming out of our Brain Bank has been critical to convincing the world that CTE is a major problem in multiple sports," Nowinski says.
Current and retired athletes pledging to donate their brain raises awareness of the research. It also encourages other families to donate when a loved one dies, he said.
"From 2009-2011 we had dozens of high-profile athletes pledge to donate their brains, and now everyone in America who follows sports is aware of brain donation, which has allowed us to study 178 brains as well as share the tissue to launch 20 new research initiatives with researchers around the world," he said.
Nowinski commends the athletes involved. Athletes like Valentine, the man he'll soon meet over dinner in Melbourne.
"I do admire Shaun for speaking out on the issue and pledging his brain," Nowinski says. "It takes courage to share with the world your personal medical information, as it can open him up to criticism and impair his ability to get a job in the future.
"But on the positive side it raises awareness of the problem, which can encourage other athletes in distress to seek help, as well as help parents, coaches, and athletes appreciate that there are significant consequences to concussions. I hope more players follow his lead."