Nathan E. Cook, Grant L. Iverson, Bruce Maxwell, Ross Zafonte, Paul D. Berkner
Introduction
A concussion is a mild traumatic brain injury (1). Primary care pediatrics is the most common initial point of concussion care for children (2). In a recent survey of pediatricians, essentially all (99%) had treated at least one patient, and half (50%) had treated six or more patients for concussion in the previous year (3). Professional consensus statements have identified attention-deficit/hyperactivity disorder (ADHD), a common neurodevelopmental disorder marked by problems with inattention, difficulty concentrating, poor impulse control, and excessive activity (4), as an important preexisting health condition to consider with regard to concussion management and recovery (5–7). Youth with ADHD are at greater risk of bodily injuries (8–11) and have a greater lifetime history of concussions (12–16) compared to those without ADHD. Pediatricians also play a central role in treating and managing ADHD. Almost half of youth with ADHD (42%) receive treatment for their symptoms solely through their primary care physician (17).
Most concussed children and adolescents experience rapid symptom improvement during the first 2 weeks after injury, and symptoms lasting longer than 1 month are considered “persistent” (1). Although studies of more severe forms of neurotrauma suggest that ADHD might be associated with worse outcome (18–20), the role of ADHD as a risk factor for prolonged symptoms or worse outcome following sport-related concussion remains poorly understood. A systematic review examining predictors of clinical recovery from concussion concluded that available studies do not support an association between ADHD and worse clinical outcome (21). A follow-up systematic review focused specifically on the role of preexisting ADHD as a risk factor for prolonged symptoms or worse outcome following concussion identified several major limitations regarding the available literature that preclude definitive conclusions (22). For example, only one study to date has been specifically designed to examine if ADHD was associated with prolonged concussion recovery and that study did not find an association (23). Moreover, two-thirds of the studies included fewer than 15 ADHD cases, no studies examined time to return to school as an outcome, no studies examined whether youth with ADHD who are taking medication experience different recovery trajectories, and no studies considered or controlled for prior concussions as an important potential covariate (22). Using a large, injury surveillance database, the current study sought to prospectively examine whether adolescents with ADHD have prolonged return to school and sports following concussion compared to those without ADHD, and whether medication status and concussion history are associated with recovery time. We hypothesized that having ADHD would not be associated with longer recovery time.