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The question

In your opinion, how connected are concussions and depression?

The answer

A timely question given the recent attention in the news about athletes with histories of head injuries and depression. The answer to this question is not a straightforward yes or no, as depression is a complicated process which involves a number of variables such as genetics, environmental influences, and other conditions.

That being said, concussion or previous head injury does seem to be one of the risk factors correlated with an increased risk of development of depression.

Concussion is a mild traumatic brain injury that generally happens after a blow to the head. After a concussion, symptoms of short-term memory loss, confusion, headache, dizziness, and fatigue can occur. In general, these symptoms last a few days to weeks and will resolve over time.

While it is reassuring that these short term changes seem to resolve, it is concerning that certain symptoms such as change in neurologic functioning in terms of memory and mood impairment may persist for longer periods of time.

There are several interesting studies done in recent years that have looked at the correlation between concussions and depression in high performance athletes in contact sports. The main findings are that those that suffer from multiple concussions have a higher risk of depression.

In 2003, the National Football League studied over 2,000 players with concussions and found a higher risk of depression in those who have not had head injury. Specifically, players who had 3-4 concussions had double the risk of depression compared to those who had no history. Those with 5 concussions had triple the risk.

McGill's Montreal Neurological Institute conducted a study using MRI imaging looking at brain activity. They found that MRI results of those athletes who had suffered from concussions had similar patterns of brain activity as people with major depressive disorder. They concluded that those who had no previous history of depression, after a concussion - had a higher risk of becoming depressed.

Interestingly, they noted that there were actual changes in the anatomy of the brain after concussion that made an injured brain look like a depressed brain.

Again, depression is a complex process and involves chemical reactions and imbalances in the brain. Concussions seem to disrupt these normal processes. Further studies need to be conducted to look at how long these changes last and if there is a reversible pattern to these changes or if they are permanent.

For now, it does raise alarm and should draw attention to safety regulations while playing contact sports, recovery time after concussion and increase our awareness of the significant impact of concussions on the well-being of those who have been or are at risk of having head injuries.

Send family doctor Sheila Wijayasinghe your questions at She will answer select questions, which could appear in The Globe and Mail and/or on The Globe and Mail web site. Your name will not be published if your question is chosen.

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