A survey of 576 male former first division soccer, ice hockey and rugby players from France, Finland, Ireland, Norway, South Africa, Spain, Sweden and Switzerland found that multiple concussions resulted in higher rates of common mental illness.
"This is an important piece of research that suggests concussion might be a contributor to the mental health problems suffered by many players," FIFPro's chief medical officer Dr. Vincent Gouttebarge, said in a statement.
"We as football stakeholders -- federations, clubs and player unions -- need to be alert to the mental health of players, both during and after their careers."
Gouttebarge, who carried out the study with sports medicine experts from the South Africa, Japan and Britain, said better education was needed to warn players of the risks.
The study found that athletes who suffered four or five concussions during their career were 1.5 times more likely to report symptoms of common mental disorders.
Those who suffered six or more concussions were between two and five times more likely to report symptoms.
A separate FIFPro study found that footballers are also more prone to mental health problems after long-term injuries.
"Players who miss more than 28 days through injury are two to seven times more likely to experience symptoms of common mental disorders in the subsequent 12 months than counterparts who did not have any injuries," FIFPro said.
(Reporting by Martyn Herman; Editing by Christian Radnedge)
