Brain injury experts find that combat veterans exposed to repeated mild explosions show chronic changes in neuron activity in certain brain regions - and the more blasts they are exposed to, the more of the lasting changes they show.
The new study - led by researchers from VA Puget Sound Health Care System and the University of Washington (UW), both in Seattle - shows that a brain region known as the cerebellum is particularly vulnerable to repetitive mild traumatic brain injury (mTBI) in both mice and humans and concludes that more attention needs to be paid to changes in this region.
The authors hope the finding will help the search for more effective treatments for mTBI, which they note is often referred to "as the signature injury of the wars in Iraq and Afghanistan."
Reporting in Science Translational Medicine, the team describes how mild blast-exposed mice also lose neurons in the same brain regions as the veterans, and that the pattern of loss is similar to that first seen in retired boxers 40 years ago.
While many veterans exposed to explosions suffer mTBIs, it is not clear how they affect their brains.
'We should pay more attention to how mTBI affects the cerebellum'
There is a large gap in our understanding of how the injuries that develop due to mild blast relate to the brain changes that researchers see on neuroimaging scans, note the researchers.
- mTBI is another term for concussion
- There is increasing concern that people who sustain multiple mTBIs are at risk for prolonged or permanent brain damage, including early onset dementia
- Worldwide, more than 250,000 American service members have been diagnosed with mTBI.
To try and reduce the knowledge gap, the researchers focused on changes to a brain region known as the cerebellum - once thought to be mostly important for integrating sensory information and movement, but now thought to also influence emotional state.
They found that mice exposed to mild blasts suffer injury in specific areas of the cerebellum that correspond to abnormalities seen in brain scans of similar regions in blast-exposed combat veterans.
Senior author David Cook, a scientist at the VA Puget Sound Health Care System, and a UW research associate professor of medicine and pharmacology, says:
"The similarities we see in the pattern of neuron injury in the cerebellum of mice, the neuron loss previously seen in boxers, and our neuroimaging findings in veterans is a step toward reducing this knowledge gap."
Coauthor Elaine Peskind, a professor in psychiatry and behavioral sciences and co-director of the Mental Illness Research, Education, and Clinical Center at VA Puget Sound, says 75% of the mTBI patients she treats also have post-traumatic stress disorder (PTSD).
"Problems with mood, irritability and impulsivity are very common in our mTBI veterans. These findings suggest we should pay more attention to how mTBI affects the cerebellum if we want to fully understand the emotional difficulties experienced by veterans with mTBI."
The study follows another that Medical News Today recently reported on how MRI scans are showing brain changes in a surprisingly high proportion of active duty military personnel who suffer blast-related mTBI.