Mild traumatic brain injury or mTBI among combat veterans have long been linked to explosive blasts. However, it is only now that experts found where exactly in the brain the harm occurs as well how it happens.

A research team from the Veterans Affairs Puget Sound Health Care System and the University of Washington (UW) analyzed brain scans of combat veterans. They also conducted similar research in mice to see where and how mTBI occurs.

The team has found that the cerebellum is highly susceptible to the recurring explosive blasts. The cerebellum is a brain part responsible for coordinating balance and movement as well as several cognitive skills.

Among former soldiers in the Afghanistan and Iraq wars, mTBI is referred to as the "signature injury" due to it prevalence. Across the world, there are about 250,000 to 500,000 U.S. military members diagnosed with this signature injury.

Lead author James S. Meabon expressed that these TBI types are rarely heard of because most people dismiss these milder types if they are not suffering from a more severe form of brain injury. Meabon is a geriatrics and psychiatry expert at VA Puget Sound and UW.

More than 40 former soldiers suffered an average of 21 mTBIs due to explosions in the recent wars and some even exceeded 100 brain injuries. The higher the blasts encountered, the lower the glucose metabolism levels get in the cerebellum. Glucose metabolism is a brain activity marker.

In the animal lab test, the same damage was found in the cerebellums of mice exposed to repeated blasts via the "shock tubes." In this particular study, the blasts damaged some parts of the blood-brain barrier.

This resulted in death of several neurons in the cerebellum and protein buildup, a marker of Alzheimer's disease and dementia. Brain scans of both mice and human subjects revealed further structural damages in the fibers that connect brain regions together.

"We need to pay more attention to the cerebellum," said VA scientist David Cook, who is also a research associate professor of medicine in pharmacology at UW.

The findings could help the scientific and medical communities deal with mTBI's effects on the cerebellum among former soldiers. It can also aid in better understanding of the emotional challenges former soldiers face.

The study was published in the journal Science Translational Medicine on Jan. 13.

Photo: The U.S. Army | Flickr

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