Even a single concussion could lead to a substantially higher risk of developing Parkinson’s disease later in life. That was the takeaway from a new study that analyzed the brains of military veterans, including those who suffered from any kind of traumatic brain injury, or TBI.\nIn a study published Wednesday in the journal Neurology, researchers took a look at over 320,000 U.S. veterans aged 31 to 65, gathering information from three Veterans Health Administration databases. Out of these subjects, approximately half were diagnosed with some sort of brain injury, including concussions (also known as minor traumatic brain injuries) and moderate to severe TBIs, during their lifetimes.\nDuring the follow-up period, which took an average of 4.6 years, 1,462 of the veterans received a Parkinson’s disease diagnosis. These included 949 participants who were found to have suffered a TBI in or out of the service, and 513 participants who suffered no such injuries in their lifetimes.\nIn all, patients who suffered traumatic brain injuries such as concussions were 56 percent more likely to develop Parkinson’s disease than those who never had a TBI; according to HealthDay, this figure rose to 71 percent when the researchers adjusted for age, race, educational level, and other risk factors. Furthermore, those who had moderate to severe TBIs were 83 percent more likely to be diagnosed with Parkinson’s than those with no TBI history.\nDespite those figures, Live Science pointed out that the overall risk of developing the condition remained below 1 percent, even for those whose brain injuries went beyond concussions. Only 0.47 percent of the concussed veterans developed Parkinson’s, while 0.75 percent of those who had moderate to severe TBIs were diagnosed with the disease. Nevertheless, the researchers stressed that the results of their study shouldn’t be taken lightly, as concussions can be quite common in adults.\n\nJust one concussion can increase your risk of developing Parkinson’s, researchers warn https://t.co/GtBBx3lNOM\n— Rob Deutschmann (@robdeutschmann) April 21, 2018\n\n“Upwards of 40 percent of adults have had a traumatic brain injury, so these findings are definitely concerning,” said study co-author Raquel Gardner, an assistant professor of neurology at the University of California, San Francisco.\nAlthough it isn’t clear why concussions and the risk of Parkinson’s disease are often linked to each other, HealthDay reported that the study supports the belief that certain athletes developed Parkinson’s due to their involvement in contact sports, with the late boxing legend Muhammad Ali cited as the most famous example. According to Gardner, it’s still impossible to link Ali’s brain injuries with his Parkinson’s diagnosis, though there’s a possibility that both were connected to each other.