When the brain trauma was more severe, the risk was even higher

A new study of hundreds of thousands of U.S. armed forces veterans concludes that banging your head severely enough to lose consciousness can dramatically increase the risk of Parkinson’s, the brain disease marked by tremors, slow movements, balance problems and difficulty walking.

While the overall numbers are relatively small, former members of the military who had received a concussion at some point in their lives were 56 percent more likely to develop Parkinson’s than veterans who had not been knocked out, who had not experienced an altered state of consciousness or who had not had amnesia for as long as 24 hours.

When the brain trauma was more severe, the risk was even higher, Reuters reports.

This is not the first study to show that even mild traumatic brain injury increases the risk for Parkinson’s disease. But we were able to study every single veteran across the U.S. who had been diagnosed at a Veterans Affairs hospital, so this is the highest level of evidence we have so far that this association is real,” lead author Dr. Raquel Gardner of the San Francisco VA Medical Center told Reuters Health.

The importance of the discovery goes beyond veterans, the research team writes in the journal Neurology.