Effect of coffee on dual-task performance

Abstract

PURPOSE: To assess the effects of coffee on dual-task performance (DtP). METHODS: 23 college-aged individuals (15/8 m/f; 25±3.4 yrs) participated in this study. Each participant attended 3 sessions (Familiarization, Baseline, and Experimental). Before each session, participants were asked to abstain from consuming caffeinated beverages the night before testing. The DtP assessment was completed during all three visits, this consisted of testing cognition (Stroop color-word test/ N-back test) while measuring balance (modified CTSIB) at the same time. The modified CTSIB test consist of four, 30-second tests; Condition 1; eyes open on a firm surface, Condition 2; eyes closed on a firm surface, Condition 3; eyes open on a foam surface, Condition 4; eyes closed on a foam surface reporting the Stability Index as the average position of the participant’s body from center. In Conditions 1 and 3, subjects were asked to stand on the balance machine with eyes open and respond to the Stroop color-word test by naming the color of a word that appears on the screen in front of them in a color different from its name. In Conditions 2 and 4 of balance test, the N-back test was completed with eyes closed and participants responded by saying ‘yes’ when a word read had already been read aloud two words previously. Additionally, on the Experimental visit participants were asked to consume one cup of brewed coffee (12 oz) that contain 240 mg caffeine, and after 30 minutes the DtP assessment was repeated. Statistical analysis was performed using paired sample t-test, with significance set at p ≤ 0.05. RESULTS: Outcomes suggest that the DtP assessment showed significant differences between Condition 1 (p= 0.018) and Condition 3 (p= 0.013) at Baseline compared to Familiarization. Moreover, after receiving coffee the results of all DtP assessments indicated no significant difference between Baseline and Experimental (p= 0.063; p= 0.390; p=0.992; p= 0.204). CONCLUSION: The data of this study suggests that the DtP assessment requires a Familiarization visit. In addition, significant improvement appears on DtP in Condition 1 and 3, but it does not report any significant effect on DtP after consuming coffee.