Studies continue on TBI, Parkinson’s
DEAR DOCTOR: I had several concussions when I was younger due to various sports activities. Now I read that a single concussion can raise the risk of Parkinson’s disease. Just how serious is this increase in risk?
DEAR READER: The association between severe and moderate traumatic brain injury and Parkinson’s has been recognized for some time. Severe traumatic brain injury is an injury that leads to a loss of consciousness or coma that lasts for more than 24 hours and is evident on a brain imaging test. Moderate traumatic brain injury leads to a loss of consciousness for one to 24 hours and is evident via imaging. With mild traumatic brain injury, loss of consciousness lasts from seconds to minutes and brain imaging studies don’t reveal brain injury. The majority of people describe this as a concussion.
The question posed by the study you reference is whether mild traumatic brain injury can lead to Parkinson’s disease. The study looked at data from the Veterans Health Administration database. Overall, veterans with
traumatic brain injury had a 71 percent relative increase in the risk of Parkinson’s disease compared to those without TBI. The veterans with moderate or severe TBI had an 83 percent greater risk of Parkinson’s, while those with mild TBI had a 56 percent relative increase in risk.
Why would traumatic brain injury lead to Parkinson’s disease? Lewy bodies, abnormal accumulations of protein in the brain, have been known to contribute to Parkinson’s, and a component of these proteins, called alpha-synuclein, is seen in the cerebrospinal fluid of those who have had severe traumatic brain injury. In addition, autopsy studies have found an association between early-life traumatic brain injury and Lewy bodies in the brain.
It’s good to understand the association between TBI and Parkinson’s, but no one should panic just yet over the risk of Parkinson’s caused by prior traumatic brain injuries.
Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles.