Abstract:
Context: The management of mild traumatic brain injury (MTBI) has become an area of great concern and controversy in the athletic setting. Numerous states have adopted legislation mandating evaluation procedures and return to play criteria for interscholastic athletics, while other sport governing bodies have adopted similar policies. Many of these recommend neurocognitive tests like Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) as a management tool. Due to the restrictive nature of current management plans, anecdotal concerns have been raised regarding athletes trying to cheat the assessment and return to play sooner. Various stimulants have been shown to improve reaction time, visual information processing and working memory, which are similar to the tasks used during ImPACT. Thus, it is possible that stimulant use could improve performance during neurocognitive testing for MTBI. Objective: The purpose of this investigation was to examine the effects of a nutritional supplement containing stimulants on ImPACT performance. Design: A randomized and counterbalanced double blind cross over design was used. Setting: ImPACT was performed on a desktop computer in a quiet, fully enclosed and illuminated room at normal room temperature. Participants: Health males and females (age=20.6±1.2 y, height= 168.5±10.7 cm, mass= 67.6 ±15.2 kg) with no history of physician diagnosed head injury, learning disability or any form of attention deficit disorder volunteered. Potential subjects were excluded if they were prescribed any type of stimulant or monoamine oxidase inhibitor for regular use. Interventions: Subjects were assessed at the same time of day under three conditions, treatment, placebo and control with each separated by a period of one week. During the treatment condition, subjects ingested 5.5 g of a supplement (Jacked 3DTM, USPlabs) containing a proprietary blend that included caffeine and 1,3dimethylamylamine (DMAA) in capsule form with water. The placebo condition consisted of 5.5 g of dextrose in identical capsule form. Main Outcome Measures: ImPACT composite scores for verbal and visual memory, visual motor speed, reaction time, impulse control and a cognitive efficiency index (CEI) were compared under each of the three conditions and were assessed 30 min after ingestion. Results: A significant difference was observed (F2,22=4.31, p=.026) when comparing reaction time, as the subjects reacted faster during the treatment condition (.535±.03 s) as compared to the placebo (.553±.03 s) and control (.554±.03 s) conditions. A significant difference (F2,22=4.07, p=.031) was also observed for the CEI, as the subjects scored higher during the treatment condition (.486±.09) as compared to the placebo (.415±.10) and control (.409±.12) conditions. Conclusions: The results suggest that stimulant ingestion 30 min prior to test administration results in improved reaction time, visual processing speed and memory. However, the question of clinical significance remains, as it is unclear if this would result in an earlier return to play decision.