Tributes and messages of support have come flooding in after news broke that Carl Hayman has been diagnosed with early-onset dementia.
It's understood the former All Blacks star has also been told he might have chronic traumatic encephalopathy (CTE) too - a disease directly linked to concussions and repeated blows to the head.
Hayman is just 41 years old.
"I spent several years thinking I was going crazy," Hayman told Dylan Cleaver's The Bounce.
"At one stage that's genuinely what I thought. It was the constant headaches and all these things going on that I couldn't understand."
Hayman's deteriorating condition since his retirement from rugby saw him turn to alcohol as his behaviour became more and more uncontrollable.
He even got pinched on domestic violence charges while in France, but received a suspended prison sentence.
Realising that something wasn't right, Hayman decided to undergo a medical examination, although he admits he was skeptical at first.
"I um'd and ah'd for about 12 months about whether I'd do anything about it and find out if something was wrong with me, or whether I would just get on with life and hope for the best," Hayman added.
"I went to the doctors here before I went to the UK but the process seemed like it was going to take a long time and I was getting to the point where I needed answers," he says.
"It would be pretty selfish of me to not speak up and talk about my experience when I could help a guy in New Zealand perhaps who doesn't understand what's happening to him and has no support network to lean on."
Concussions and head knocks is a hot topic within sport right now.
Various sporting codes from rugby league and union and even football have conducted extensive research into the effects of continued blows to the head.
For contact sports like union and league or even American football over in the United States, a number of high-profile former athletes have come out and spoken openly about their experiences of concussions and how it is impacting them today.
Football officials have even looked into completely scrapping heading within the game in a bid to eradicate any contact with the head.
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