A diagnosis of a mild concussion or a traumatic brain injury (TBI) raises the risk of developing Parkinson’s disease, according to a new study from the University of California, San Francisco.
The present study was based on previous research that demonstrated a significant connection between moderate to severe TBIs and an increased risk of Parkinson’s disease. However, the findings on mild TBI and Parkinson’s haven’t been as clear.
TBI occurs when a head injury causes damage to the brain, and it affects millions of people in the United States every year. Half of all TBIs are a result of car accidents. People with the mildest cases of TBI experience headache, neck pain, nausea, dizziness, and tiredness. In the more severe cases, patients experience seizures, chronic nausea, slurred speech, dilated eye pupils, and weakness or numbness in the arms and legs.
In the study, researchers recruited 325,870 United States veterans, half who had experienced either mild, moderate, or severe TBIs but had no Parkinson’s disease or dementia at the start of the study. Participants were between the ages 31 and 65, and researchers followed them for an average of 4.6 years.
Researchers defined moderate to severe TBI as “loss of consciousness for more than 30 minutes, alteration of consciousness of more than 24 hours, or amnesia for more than 24 hours.” All TBIs in the study were diagnosed by a physician.
At the end of the study, 1,462 participants had been diagnosed with Parkinson’s, most within five years of the beginning of the study. More specifically, 0.58 percent of participants with a TBI developed Parkinson’s, while 0.31 percent of participants with no TBI developed the disease.
Overall, having any kind of TBI increased a person’s risk for Parkinson’s by 71 percent. Additionally, study participants with TBIs were diagnosed with Parkinson’s an average of two years earlier than those without a TBI. Before conducting their analysis, researchers made adjustments for age, sex, race, education, diabetes, and high blood pressure
"This study highlights the importance of concussion prevention, long-term follow-up of those with concussion, and the need for future studies to investigate if there are other risk factors for Parkinson's disease that can be modified after someone has a concussion," explained lead study author Raquel C. Gardner, MD. "While our study looked at veterans, we believe the results may have important implications for athletes and the general public as well."
The present study was published in the journal Neurology.