May 16, 2012

expert reaction to study of blast injuries, the brain and resulting psychiatric problems

A paper in Science Translational Medicine outlined how military veterans suffering blast-related brain injury may be at increased risk for developing chronic traumatic encephalopathy or CTE, a degenerative brain disease found in people with a history of repetitive brain trauma.

Simon Wessely, Professor of Epidemiological and Liaison Psychiatry at the Institute of Psychiatry, King’s College London, said:

“This study adds significantly to our knowledge about what serious or repeated concussion does to the brain. The animal work is impressive, particularly showing the importance of accelerating/decelerating injury.

“However, we need to remember that this is not the same as mild concussion. Nor is this the same as post-traumatic stress disorder, with which mild traumatic brain injury is sometimes confused.

“Finally, it cannot explain why mild traumatic brain injury/concussion seems to be more common in US than UK Forces, despite fighting the same enemy on the same terrain and, at least in recent years, sustaining the same rate of casualties.”

‘Chronic Traumatic Encephalopathy in Blast-Exposed Military Veterans and a Blast Neurotrauma Mouse Model’ by Goldstein, L. et al., published in Science Translational Medicine on Wednesday 16th May.

Professor Robin Cleveland of Oxford University, a member of the research team and an author of the paper in Science Translational Medicine, said:

“We investigated the physical mechanisms that produce brain injury in soldiers subject to blast waves. Analysis of brain tissue from veterans who had been subjected to blast waves showed very similar damage to that observed in brain tissue from professional American football (gridiron) players.

“The damage to brain tissue in American football players has been associated with a progressive neuro-degenerative disease (chronic traumatic encephalopathy) which induces depression, aggression, memory loss and even suicide – the most recent being Junior Seau on 2 May 2012. The damage in football players has been linked to acceleration forces due to head impact and the goal here was to see if the same process was happening with blast induced brain injury.

“Using a mouse model in a shock tube the dynamics of the head oscillation were tracked with a high-speed movie and very high accelerations were recorded. The brain tissue was examined and the morphology of the damage and the damage to neurons associated with a specific protein that contributes to neuro-degenerative diseases was the same as that observed in tissue from football players and veterans.

“Animals subject to a single shock wave exhibited memory retention problems when given a task associated with finding their way through a maze. In contrast animals in which the head was immobilised did not exhibit tissue damage or memory problems.

“The data suggests that it is the oscillation of the head that produces damage to tissue rather than the direct passage of the shock wave through the brain. The consequence is that to protect the head from injury the use of a helmet may not be the optimal strategy, rather a restraining device that reduces motion of the head and neck may be more effective.”

Dr Jennifer Wild, Senior Research Fellow in Clinical Psychology, Department of Experimental Psychology, University of Oxford, said:

“This is a fascinating and well-conducted study, which could lead to new safety measures to reduce brain damage amongst soldiers exposed to bombs.

“The team isolated one of the key mechanisms which causes brain damage after exposure to a bomb blast. The main damage appears to come from the wind caused by the blast, which rocks the head at a high speed.

“The investigators exposed mice to bomb blasts to look at what would help reduce brain trauma in the face of explosions. They discovered that immobilizing their heads during blasts protected them from developing the usual pattern of brain damage linked to surviving a bomb explosion. This has invaluable implications for future safety measures which may involve developing special helmets to help keep soldiers heads still during a blast.”