The Effects of Caffeine on Reaction Time of Two Neurocognitive Tests

Abstract

Context: A concussion is defined as a traumatically induced transient disturbance of the brain caused by a biomechanical force. These problematic injuries can prevent athletes from participating in physical activity for a number of days, weeks, or even months. Caffeine is known for improving mental alertness in everyday tasks and is found in many popular drinks such as, coffee, tea, energy shots, and even soda. Due to its increase in memory, mental alertness, and concentration, caffeine could potentially be utilized to improve the outcomes of post-concussion neurocognitive testing. This improvement would allow athletes to return to play before they have returned to full health, thus potentially setting them up for further brain trauma. Objective: To evaluate caffeine's effect on reaction time (RT) when measured with two neurocognitive evaluation tools. Design: Cross-sectional Observation. Setting: Athletic Training Laboratory. Patients or Other Participants: Eighteen (14 male and 4 female) (Age = 21.7 ± 1.4 years, Height = 175.0 ± 9.1 cm, Weight = 75.6 ± 12.5 kg) healthy collegestudents participated in the current study. They were excluded if they had a history of high blood pressure, diagnosed heart condition, neurocognitive disorder or clinically diagnosed mental illness, more than one concussion in their lifetime or one within the last year, caffeine sensitivity, currently taking any prescribed medications, except birth control, ingest more than 500mg of caffeine daily or have been exposed to Immediate Post-Concussion Assessment and Cognitive Testing (ImPACT) or Kind-Devick tests within the last year. Interventions: Participants were randomly assigned into either a caffeine or placebo group. Following ingestion of the intervention, participants waited 45 minutes to begin their first assessment, either ImPACT or the King-Devick (KD) Test. Immediately following the first assessment, participants were evaluated using the other neurocognitive tool. Follow-up testing was conducted one week later under the opposite intervention. The testing order remained the same between the two testing sessions. Main Outcome Measures: The reaction time composite score produced by ImPACT and the overall King-Devick time were recorded and evaluated for initial testing and the follow-up appointment. These domains were compared to evaluate caffeine's effect on reaction time compared to the placebo intervention. Scores were also evaluated for each testing session regardless of the intervention. This evaluation will indicate if there is a practice effect overtime. Results: A significant improvement was noted in the ImPACT RT score following ingestion of the stimulant (0.53 ± 0.05 seconds) compared to the placebo substance (0.56 ± 0.07 seconds, P=.007). The KD test resulted in a significant decrease in overall time between testing session 1 and testing session 2, suggesting a practice effect (38.2 ± 5.6 seconds, 35.5 ± 5 seconds, P= ≤ 0.001). Conclusions:Participants of the current study were able to identify a computerized stimuli 0.03 ...