PEOPLE WHO HAVE been diagnosed with a mild concussion, or a mild traumatic brain injury, may have a 56% increased risk of developing Parkinson’s disease, according to a new study.

The researchers took a pool of US veterans who had sustained brain injuries and examined their susceptibility to Parkinson’s disease.

“Previous research has shown a strong link between moderate to severe traumatic brain injury and an increased risk of developing Parkinson’s disease, but the research on mild traumatic brain injury has not been conclusive,” study author Kristine Yaffe, of the University of California said.

“Our research looked at a very large population of US veterans who had experienced either a mild, moderate or severe traumatic brain injury in an effort to find an answer to whether a mild traumatic brain injury can put someone at risk,” they said.

The study

For the study, researchers found 325,870 veterans from three US Veterans Health Administration medical databases. Half of the study participants had been diagnosed with either a mild, moderate or severe traumatic brain injury and half had not.

Moderate to severe traumatic brain injuries were defined as a loss of consciousness for more than 30 minutes. Mild traumatic brain injuries were defined as loss of consciousness for zero to 30 minutes, alternation of consciousness of a moment to 24 hours or amnesia for zero to 24 hours.

The participants, who ranged in age from 31 to 65, were followed for an average of 4.6 years. At the start of the study, none had Parkinson’s disease or dementia. All traumatic brain injuries were diagnosed by a physician.

A total of 1,462 participants were diagnosed with Parkinson’s disease at least one year and up to 12 years after the start of the study.

A total of 949 of the participants with traumatic brain injuries (0.58% of total) developed Parkinson’s disease, compared to 513 of the participants with no traumatic brain injury (0.31%). A total of 360 out of 76,297 with mild traumatic brain injury (0.47%) developed the disease and 543 out of 72,592 with moderate to severe traumatic brain injury (0.75%) developed the disease.

After researchers adjusted for age, sex, race, education and other health conditions like diabetes and high blood pressure, they found that those with any kind of traumatic brain injury had a 71% increased risk of Parkinson’s disease. Those with moderate to less severe traumatic brain injuries bad an 83% increased risk.

Those with a mild traumatic brain injury had a 56% increased risk of Parkinson’s disease.

Earlier diagnosis

Researchers also found that those with any form of traumatic brain injury were diagnosed with Parkinson’s disease an average of two years earlier than those without a traumatic brain injury.

“This study highlights the importance of concussion prevention, long-term follow-up of those with a 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,” study author Raquel C Gardner of the University of California said.

“While our study looked at veterans, we believe the results may have important implications for athletes and the general public as well,” they said.