Can concussions lead to depression?

December 11, 2013


Can concussions lead to depression?

There has been an increasing amount of research on the possible long-term effects of concussions, providing sports medicine physicians, coaches and athletes with more insight on the traumatic head injury. While once thought of as an injury with only temporary damage, new studies have shown that concussions often lead to various health complications down the road, ranging from seizures to extreme changes in one's mood.

One such study, recently published in the journal Biological Psychiatry, looked at how a concussion can cause symptoms of depression later in life. Using mice as their subjects, researchers found that excessive inflammation of brain cells occurs following a concussion. The microglia - immune-system cells that help fight infection and injury - go on "high alert" and tend to overact, causing inflammation. As these cells continue to be on high alert, especially when faced with new challenges of the immune system, the inflammation triggers depression-like symptoms.

Although the researchers tested these results on mice just one week after a moderate brain injury, they believe the symptoms would increase as time goes on.

"If we had waited three, six or nine months, the symptoms probably would have gotten even worse," said Jonathan Godbout, the study's lead author and an associate professor of neuroscience at The Ohio State University. "A lot of people with a history of head injury don't develop mental-health problems until they're in their 40s, 50s or 60s. That suggests there are other factors involved, and that's why we're looking at this two-hit idea."

Godbout and his colleagues believe that it's not solely the concussion that brings about depression, but a combination of the minor head injury and threats to the immune system. While many of the mice were able to recover within one month of their brain injuries, Godbout stated that the microglia in their brains remained in this high-alert state, thereby making them more susceptible to depression in the future.

"These results tell us the TBI [traumatic brain injury] mice are having an amplified and prolonged activation of microglia, and that was associated with development of depressive symptoms in the mice," Godbout said.

Exploring the link between depression and head injuries
This recent study from Godbout and his colleagues builds upon previous research analyzing the relationship between concussions and mood disorders such as depression. According to Time magazine, two reports released in early 2013 found that professional football players might be more prone to symptoms of depression because of the concussions they suffered during their careers.

Both studies looked at the white matter - a mass of insulated nerve fibers - in the brains of football players who experienced multiple head injuries and were diagnosed with depression, and came to similar conclusions.

"[White matter] is kind of like bundles of cables that are connecting different parts of the brain," Kyle Womack, the author of both studies, told the news source.

According to Womack, the football players who were exhibiting signs of depression had abnormalities in their white matter. While these fibers transmit signals, they can easily stretch or tear following a concussion, resulting in depression and other cognitive impairments. The damage of the white matter seemed to correlate to the severity of depression.

Although Womack and his colleagues stated that more research needed to be conducted, neurologist John Hart, who participated in the study, told the news source that knowing the signs of depression is as important as sports injury prevention for former and current football players. Other NFL players agreed.

"If you catch it early or late, there are things you can do to improve your condition," said Daryl Johnston, a former NFL football player who was included in the study. "The brain is regenerative for life, and we can restore faculties that just a few years ago were thought to be lost forever."

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