It is both remarkable and puzzling that service members in the first 30 days following a mild TBI were significantly more likely to receive an initial diagnosis for all but one addiction-related disorder when compared with others who received treatment for a different injury. While the occurrence of a TBI is systematically associated with subsequent diagnosis of addiction-related disorders in a way that other injuries are not, a causal relationship between mild TBI and onset of dependence would not appear plausible because the behavioral patterns leading to a dependence diagnosis rarely manifest in just 30 days. Clearly, the injury is occurring during a period of maladaptive substance use. Perhaps the diagnosis and treatment of behavioral symptoms from mild TBI facilitates the identification of coexisting substance use problems in a way that treatment for other bodily injuries does not. Another possibility that leads to differential identification of a person with emerging substance dependence is if the consumption pattern of those with dependence was more likely to result in a TBI compared with other injury. Indeed, at least one large population study found that the likelihood of an injury event including a TBI increased dramatically with increased blood alcohol content (3). It is plausible that across all drugs, consumption patterns consistent with addiction-related disorders creates more risk for incurring an injury that affects the brain, whether that is due to poorer decisions, greater disinhibition, and/or more impaired motor control. Such a conclusion complicates the roles of risk and consequence, obfuscating an easy public health implication.