When retired athletes suffer mental health problems, medical professionals are often quick to blame past head injuries and concussions.

Heavy hits to the head and concussions are known to increase risks of depression and even suicide, but new research suggests that may not be the only reason.

Michael Gaetz, a kinesiology professor at the University of the Fraser Valley, said concussion research tends to be "one-sided" when there are, in fact, many different issues at play.

"We're focusing exclusively on the history of brain injuries and not thinking about other factors as well,"  Gaetz told CBC On The Coast host Stephen Quinn.

Gaetz has researched concussions for nearly two decades and just published a paper in Medical Hypotheses about the causes of chronic traumatic encephalopathy, a progressive degenerative disease of the brain found in people with a history of repetitive brain trauma.

Gaetz argued that there are many reasons why a former athlete could experience depression that are not just due to a past head injury. He mentioned chronic pain from other injuries, medication use and identity crises as factors that do not get enough attention.

"Chronic pain, in and of itself, will account for a lot of the symptoms that athletes experience post-career," he said.

"Other things, like the use of substances to manage pain, substances to manage sleep and even substances like steroids that are used during their career, are linked to some of these symptoms."

Brain injuries in athletes

Concussions are known to increase risks of depression and are a concern in contact sports. (University of the Fraser Valley/flickr )

Shifting identities

Athletic identity is a newer area of research, Gaetz said, but very relevant when it comes to athletes' retirement.

"People who have a very strong identity that is linked with their career—once their career is over, it can lead to depression and can even lead to thoughts of suicide and suicidal behaviour," he said.

Focusing just on concussions as the cause of depression means other areas are ignored, to the detriment of the athletes.

"If we're ignoring the effects of a strong athletic identity, that's problematic in how we develop young athletes," he said.

"Their identity is locked into that role but they really, in some cases, are lost when they are no longer in that role."

'We haven't been very good at this'

There has not been enough varied research into concussions, Gaetz said, and that needs to change. In particular, he wants to see a more theoretical look into the problem.

"We haven't been very good at this in concussion science," he said. "We've been doing study after study after study without much direction."

This means developing different theoretical models, testing them and moving forward with a more systematic approach, he explained.

"What we need to do as scientists is approach this in a more balanced way."

To hear the full interview, click on the audio link below

With files from On The Coast.