Each year, approximately 42 million people around the world experience concussions. New research published in the journal Neurology indicates that even mild brain injuries can increase the risk of developing Parkinson’s disease.
Parkinson’s disease is a disorder in which the nervous system gradually deteriorates. Although the disease affects individuals differently, early symptoms of Parkinson’s typically include hand tremors, slow movement, stiffness, diminished facial expression, and slurred speech. As the disease progresses, patients may experience body tremors, difficulty thinking, problems with swallowing, incontinence, generalized fatigue, interrupted sleep, and feelings of depression or anxiety. Parkinson’s disease is most common in individuals over the age of 60. Men have an increased risk of developing Parkinson’s, as do individuals with close relatives who have it.
Possible causes of Parkinson’s disease
One of the hallmarks of Parkinson’s is the presence of clumps of proteins, called Lewy bodies found in the brain cells; however, it is not known if they are a cause or result of the disease1. However, new research has shown that traumatic brain injury can increase the risk of developing Parkinson’s disease.
In a recent study published in Neurology, researchers from San Francisco used medical data on just over 325, 000 American veterans to assess the risk of developing Parkinson’s disease following a traumatic brain injury. All participants were over the age of 18 (average age was about 48 years) and approximately half of the veterans had experienced a mild, moderate, or severe traumatic brain injury. A mild traumatic brain injury is categorized as a loss of consciousness lasting up to 30 minutes, a moderate injury was categorized as an alteration of consciousness lasting up to 24 hours, and a severe injury was categorized as having amnesia for up to 24 hours.
Increased brain trauma was associated with an increased risk of Parkinson’s
Nearly five years later, 1,462 of the veterans had been diagnosed with Parkinson’s disease (0.58%). This was significantly higher than the incidence of Parkinson’s among veterans without a traumatic brain injury (0.31%). The research team found that after controlling for other demographic and medical factors, increased brain trauma was associated with an increased risk of Parkinson’s. The incidence of Parkinson’s among veterans with a mild concussion was 0.47% increasing to 0.75% for veterans who had suffered moderate to severe traumatic brain injury.
Further study would help illuminate how comorbidities such as substance abuse or depression are related to Parkinson’s risk and whether early interventions can reduce this risk among individuals who have suffered a traumatic brain injury.
Written by Debra A. Kellen, PhD
(1) David J. Brooks. “Parkinson’s disease: diagnosis.” Parkinsonism Relat Disord. 2012;Suppl 1:S31-33. doi: 10.1016/S1353-8020(11)70012-8. http://www.sciencedirect.com/science/article/pii/S1353802011700128
(2) Gardner, R. C., Byers, A. L., Barnes, D. E., Li, Y., Boscardin, J., & Yaffe, K. (2018). Mild TBI and risk of Parkinson disease: A Chronic Effects of Neurotrauma Consortium Study. Neurology, 10-1212. DOI: https://doi.org/10.1212/WNL.0000000000005522