Impact of Concussions on Parkinson’s Disease Risk

Global Concussion Statistics

Each year, around 42 million individuals worldwide suffer concussions. Recent research published in the journal *Neurology* reveals that even mild brain injuries may heighten the risk of developing Parkinson’s disease.

Understanding Parkinson’s Disease

Parkinson’s disease is a progressive disorder that affects the nervous system. It manifests differently among individuals, but early signs typically include hand tremors, slow movements, stiffness, reduced facial expressions, and slurred speech. As the condition advances, patients may face body tremors, cognitive difficulties, swallowing issues, incontinence, fatigue, sleep disturbances, and feelings of depression or anxiety. The disease predominantly affects those over 60 years of age, with men being at a higher risk, particularly if they have family members with the condition.

Potential Causes of Parkinson’s Disease

A significant characteristic of Parkinson’s is the presence of Lewy bodies, which are clumps of proteins found in brain cells. It remains unclear whether these bodies are a cause or a consequence of the disease. However, recent studies indicate that traumatic brain injuries can elevate the likelihood of developing Parkinson’s disease.

Research Findings on Brain Injury and Parkinson’s Disease

A study featured in *Neurology* involved researchers from San Francisco who analyzed medical records from over 325,000 American veterans. All participants were over 18 years old, with an average age of approximately 48. Around half had experienced varying degrees of traumatic brain injury, classified as follows: mild injuries involved a loss of consciousness for up to 30 minutes, moderate injuries involved altered consciousness lasting up to 24 hours, and severe injuries included amnesia for up to 24 hours.

Incidence of Parkinson’s Disease Among Veterans

Nearly five years post-injury, 1,462 veterans were diagnosed with Parkinson’s disease, accounting for 0.58% of the cohort—significantly higher than the 0.31% incidence among veterans without a history of traumatic brain injury. The research team concluded that, after adjusting for other demographic and medical variables, increased brain trauma correlated with a greater risk of developing Parkinson’s. Specifically, the incidence among veterans with mild concussions was 0.47%, rising to 0.75% for those who suffered moderate to severe injuries.

Future Research Directions

Further investigations are needed to explore how comorbidities like substance abuse or depression relate to Parkinson’s risk and to determine whether early interventions could mitigate this risk for individuals who have sustained traumatic brain injuries.

Author and References

Written by Debra A. Kellen, PhD

References:
(1) David J. Brooks. “Parkinson’s disease: diagnosis.” *Parkinsonism Relat Disord*. 2012; Suppl 1:S31-33. doi: 10.1016/S1353-8020(11)70012-8. [Link to study](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: [Link to study](https://doi.org/10.1212/WNL.0000000000005522)