Looking ahead: Can a bump on the head change the genes in your brain?

March 17, 2015

At first glance, traumatic brain injury (TBI) may seem limited to the realm of soldiers and football players. But TBI is far more commonplace than we might imagine. In the United States alone, an estimated 1.7 million people sustain a traumatic brain injury every year, and of those, nearly 1.4 million (about 80%) are simply treated and then released from an emergency department. And there is no estimate for the number of people with a non-fatal TBI who never seek medical treatment at a hospital.

“For the general population, these mild to moderate TBIs are something to take seriously,” says Angie Bongaarts, senior scientist at the Allen Institute. “Maybe my kid is playing high school football, or I was involved in a minor car accident. We have plenty of evidence for the repercussions of the kinds of TBIs sustained by professional football players, for instance, but what about this other, more everyday end of the spectrum?”

Scientists at the Allen Institute, in collaboration with researchers at the University of Washington and Group Health in a study funded by the Paul G. Allen Family Foundation, are looking at whether a single mild or moderate TBI causes long-term changes in the brain. To do this, they are examining the brains of people enrolled in the Adult Changes in Thought study, who join the study at age 65 and are asked extensive questions, including whether they have ever had a trauma to the head that caused them to lose consciousness.

The study is examining gene expression in four areas of the brain that tend to see pathology in brain trauma: the parietal cortex, hippocampus, temporal cortex, and the white matter underlying the parietal cortex. “Interestingly, damage in the brain is not necessarily correlated with where on the skull the person is hit, since additional trauma can come from the brain sloshing around inside the skull as well,” says Bongaarts. For this study, researchers are looking at genes by analyzing the RNA present in small sections of the brain: an indication of which genes are turned on or off.

“The best case scenario is we don’t find anything, so we can say that a single mild to moderate TBI has no effect on gene expression in the brain,” explains Jeremy Miller, the scientist who is leading the RNA analysis. “And if we do find a difference, hopefully we’ll be able to come up with an explanation, and in the long term would be able to intervene to help TBI patients.”

Scientists are looking not just for signs of TBI in the brain, but also for other markers of aging and related pathologies. “Since the entire population of our study is between the ages of 72 and 102, we are also getting to collect some fascinating data on aging as well as disease-associated pathologies,” says Bongaarts. “We’re essentially getting to do a bonus study that gives insight into the molecular and genetic changes associated with aging, in addition to looking at how aging and disease could be interacting with possible TBI.”

At the moment, the team is still working to collect and analyze the RNA data, and have begun processing on just over half the tissue that will ultimately be studied. Though it’s too soon to say, Bongaarts is optimistic that the study will yield interesting and potentially helpful outcomes. “This is one of the most collaborative and exciting projects I’ve gotten to be part of, and I can’t wait to see the results,” she says.