Clarke Carlisle has claimed that there are "hundreds" of footballers who are currently suffering silently from depression.
The chairman of the PFA struggled with the illness during his days at Queens Park Rangers and believes that there are still plenty of players who are experiencing the same thing he once went through.
"I will categorically state there are hundreds of players suffering with [depression]," the Daily Mail quotes Carlisle as saying.
"The numbers in society are one in four and footballers are members of that society. The thing about football is that the reluctance to come forward and speak means there are so many guys sitting under the radar.
"As PFA chairman, I've had 15-20 guys come to me and say, 'Clarke, there's something wrong with me and I don't know what it is or where I should go'. All they know is they want to be out of football, out of the system."
Carlisle added that footballers are not immune to depression despite their wealth.
"Depression is a chemical imbalance in the brain that needs adjustment," he said. "Your wealth, job or intelligence don't make you immune.
"It's as bona fide an illness as gastro-enteritis. It needs to be diagnosed and treated. Stephen Fry is probably the most intelligent man I've ever come across - and he has suffered from it."
Carlisle has been the PFA chairman since 2010.