Researchers unveil the dangers behind continual head injuries

December 8, 2014

Topic: concussion

Laws were recently implemented regulating how concussions are treated in healthcare. As a result, people may be viewing the injury a little more closely than before.

Most know that continual blows to the head over time are not good for you. However, researchers just discovered exactly how harmful they are. The Ohio State University research team found that a few hits to the head within days of one another can inhibit the brain's ability to use sugar, which is considered a primary energy source. Sugar can also help repair brain cells that are damaged by injuries. The findings were published in the journal Neurobiology of Disease.

The brain's chance to use energy after an injury is crucial. Using mice, the researchers found that brain cells increase their energy for six days after a concussion to help recover from the damage. If people sustain a second injury before the brain is able to use the source of energy, the brain will not be able to recover. In mice, the study authors found that a lack of sugar caused brain swelling, atrophy of brain cell areas and difficulties with memory and learning.

Getting to know concussions
The U.S. Centers for Disease Control and Prevention noted that a concussion can be caused by a blow, jolt or even a mild bump to the head. Falls can also cause concussions as the brain moves quickly back and forth. The injury is not often life-threatening, but can have serious effects. 

The new study's findings were presented at Neuroscience 2014, an annual event for the Society of Neuroscience. Some of the researchers determined that even if glucose is present in the brain, poor insulin signals block the cells from using the sugar.

Most clinical research has found that two head injuries in a small period of time can be very dangerous and possibly deadly. However, it is still unknown what actually goes on in the brain. Knowing this information can help physicians and trainers determine when to clear athletes for play or military members to service.

Lead study author and OSU professor Zachary Weil noted these harms.

"Lots of data show that if two head injuries occur close together, it's not like 1 plus 1. It's more like 1 plus 10," Weil said in a statement. The researchers hope to uncover what occurs when two injuries are close together that makes people more vulnerable and if there is an indicator of whether a person will be OK or not. 

A relation to Alzheimer's disease
The study authors also noted that discovering that insulin resistance affects the brain could help give answers on why many professional athletes who have experienced several head traumas are diagnosed with chronic traumatic encephalopathy, or CTE. This condition has symptoms similar to Alzheimer's. Patients might experience memory problems, difficulty concentrating or disorientation. Research has already made a clear link between problematic insulin signals and Alzheimer's.

Once the cells are injured, they are not able to use the sugar even though it may be present. The cells cannot use the sugar because of the signals being blocked. A similar mechanism occurs in Alzheimer's where cells are constantly undernourished.

A signaling issue
In previous studies, Weil and his colleagues compared the effects of two head injuries that occurred either three days or 20 days apart. The mice who were injured twice in three days had more significant brain inflammation and axon degeneration, which are long rods that extend from the cells. The mice also could not navigate a maze as well and had difficulty remembering the lessons they learned. Neurons need healthy axons in order to communicate proper signals.

Regardless of when the second injury occurred, all mice experienced a brain energy surge six days after the injury. However, the mice that were injured again three days later did not have as high of a glucose level.

"With the second injury, demands for energy might outstrip the ability of the damaged cells to actually use the energy," Weil said in a statement.

The group also presented their follow-up work at the annual event for the Society of Neuroscience. The researchers compared healthy brain tissue to tissue from one injury and tissue from two that occurred within 24 hours. The study authors tested the tissue with insulin and then tested activation levels of a significant protein used in the activation process. For the non-injured mice, the protein was increased by the presence of insulin. Conversely, the injured brains did not respond to the presence of insulin. Without a signal, the brain cells could not access their source of glucose.

The researchers concluded they need to find ways to cause insulin sensitively instead of increase the amount of insulin.

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