The research showed 26 per cent of players reported mental health problems, with that figure rising to 39 per cent among retired players.
FIFPro’s study of 180 current players in six countries, including Scotland, Holland and the Republic of Ireland, showed that 7 per cent smoked while 19 per cent reported “adverse alcohol behaviour”.
Celtic manager Neil Lennon, former Rangers player Paul Gascoigne and ex-England star Stan Collymore have all spoken in the past of their battles against depression.
FIFPro’s chief medical officer, Dr Vincent Gouttebarge, said: “We found mental illness among former professional footballers occurs more often than in other measured populations.”
Last month, Lennon backed PFA Scotland’s campaign to highlight depression among footballers.
The Celtic manager appears in a short film, Mind Games: Mental Health In Scottish Football. Lennon has said: “There is no better life to have than being a professional sportsperson. When you are affected by this illness it could be the worst place because we are all public figures.”