The long list of symptoms
The 24 veterans in Peskind’s brain injury study, all of whom had repetitive exposure to blasts dating between two and seven years ago, show strikingly similar present-day symptoms.
Twenty-four vets felt irritable, 23 were forgetful and 23 felt anxiety or tension. Twenty-two had difficulty making decisions, 22 had mood swings and 22 had hearing problems. Twenty-one experienced slowed thinking. The list goes on, ranging from depression, to difficulty with sleep, to light sensitivity, to aggression. In addition, 21 of the 24 have combat-related post-traumatic stress disorder.
As for objective evidence to indicate that repeated blast exposure and mild traumatic brain injury causes brain changes in those vets? There hasn’t been any. Until this summer. “We now have brain imaging evidence that there are both functional and structural changes in the brain in these veterans,” says Peskind.
What changed in the brain
Using a PET scan that measured the uptake of glucose in the brain — glucose is the brain’s sole fuel — Peskind and her colleagues determined that her vets’ brains were different.
“We found that there was lower metabolism of glucose in three brain areas where it was significantly different from our controls. Those were the cerebellum, the pons and the thalamus.” (The cerebellum controls balance, movement, cognition and emotion; the pons controls arousal, attention and sleep; the thalamus is a relay station for multiple brain functions and is the brain’s center for pain perception.) These findings are being published in a special “blast concussion” issue of the journal NeuroImage (available as an e-publication ahead of print). These findings also won the first prize in the neuroscience division at the annual meeting of the Society for Nuclear Medicine this summer.
The researchers found structural changes, too. With Donna Cross, Ph.D., UW research assistant professor in the Department of Radiology, Peskind used special MRI techniques to image nerve tracts in the brain, and these tracts also showed abnormalities.
The mice and the shock tube
Evaluating vets a few years after exposure is one step, but Peskind also is interested in what will happen as the veterans age. Head injury is a risk factor for Alzheimer’s disease, a disease that often afflicts older people. But another type of dementia, chronic traumatic encephalopathy (CTE), strikes in mid-life. Repetitive head trauma, including sports-related repetitive concussion (like that experienced by boxers, football players, soccer players and hockey players) appears to be a risk factor for CTE.
What’s next for Peskind? She and her colleague, David G. Cook, Ph.D., UW adjunct research associate professor of medicine in the Division of Gerontology and Geriatric Medicine, are working with blast engineers at BakerRisk to develop a 19-foot shock tube at the VA; with it, they’ll subject mice to shock waves. This should provide a view, within the mouse’s shorter life span, of what happens as the injured human brain ages. “With the mice, we can put in genes that are risk factors for bad outcomes from head trauma and risk factors for dementing disorders such as Alzheimer’s disease and CTE,” says Peskind.
Peskind is excited about her group’s discoveries, and excited, too, to be working with people who care about the implications of her work. “The veterans have been wonderful,” she says. “This is the first research I’ve done in my life where recruitment was not a problem. We have a waiting list of about 30 veterans.”
For Peskind, it all comes down to her patients’ futures. “We’re trying to improve their quality of life,” she says.