The Effect of Caffeine on Neurocognitive Testing

Abstract

INTRODUCTION: Baseline assessments using computerized neurocognitive testing (CNT) has been advocated for the management of sport related concussion (SRC) The ImPACT is a commonly used CNT used in SRC management protocols. A potential extraneous variable, which may influence baseline ImPACT test performance, is caffeine. Caffeine ingestion is prevalent amongst children and adolescents due to the need to increase or boost energy levels. Sources of random error such as caffeine may limit the clinical utility of the baseline ImPACT assessment following a SRC. PURPOSE: The objective of this study was to examine the effect caffeine on computerized neurocognitive testing, using ImPACT, in a healthy collegiate sample. METHODS: Design: Participants consisted of 26 (n = 26), healthy, college participants. Participants completed Green’s Word Memory Test (WMT) and forms 1, 2 and 3 of ImPACT at Days 1, 7, and 14. Form 1 was administered to familiarize each participant with the ImPACT and used to employ the reliable change index. Participants were randomly assigned into two counterbalanced groups. Depending upon group assignment, each group received a 100 mg caffeine or placebo pill on Day 7 one hour prior to taking the WMT and ImPACT. The same methodology was employed using either remaining pill on Day 14. Measurement: Main outcome measures consisted of ImPACT’s Verbal and Visual Memory, Visual Motor Speed, Reaction Time, Total Symptom Score, and Impulse Control and the WMT’s Immediate and Delayed Recall, Consistency, Multiple Choice, and Paired Recall. Two-tailed paired t-tests were used to determine significant differences in performance on the ImPACT and the WMT with and without caffeine. All analyses were performed with α = .05.. Results: Our analyses revealed no significant differences for any ImPACT or WMT (p>.05) composite score with administration of caffeine or a placebo. Similar to previous research, we observed ImPACT misclassified 8 participants at Day 7, and 9 participants at Day 14. All participants included in our analyses provided a valid effort as defined by the WMT and ImPACT. Conclusions: Our results suggest caffeine in the amount of 100 mg, which is similar to an 8 oz can of a typical energy drink (Redbull, Rockkstar, Monster, Full Throttle), does not influence performance on ImPACT. Future research is needed with a larger sample size and administration of varying amounts of caffeine to determine its influence on performance on CNTs.