Recently, there has been attention on the association of traumatic brain injury (TBI) with progressive neurodegenerative diseases; such as, Parkinson’s disease. However, the association between mild TBI and Parkinson’s remains unclear. Therefore, the authors used 3 nationwide Veterans Health Administration databases (Comprehensive TBI Evaluation, National Patient Care Databases, Vital Status File Database) of inpatients and outpatients seen between 2002-2014 to determine the risk of developing Parkinson’s disease following a TBI. Authors age-matched 162,935 patients (~48 years of age) with TBI diagnosis without dementia, Parkinson’s disease, or secondary parkinsonism at baseline to a random sample of patients without any of the aforementioned conditions. The authors defined TBI exposure as a diagnosis of TBI after a comprehensive neurological assessment or by at least one inpatient or outpatient TBI diagnosis from a list of ICD-9 codes. Parkinson’s disease was defined as any inpatient or outpatient diagnosis of ICD-9 332.0 at least 1 year after TBI. The average follow-up was ~5 years. The authors found that a veteran with a prior TBI (0.6%) is >56% more likely to develop Parkinson’s disease than a veteran without a prior TBI (0.3%). This finding was consistent even after accounting for factors such as medical comorbidities (diabetes, hypertension, cerebrovascular disease) and psychiatric disorders (anxiety, post-traumatic stress, drug/alcohol use). Furthermore, this finding was consistent among people with mild or moderate-severe TBI.