Subjective and objective effects of coffee consumption — caffeine or expectations?

• DOI: 10.1556/aphysiol.101.2014.012
• Publication Date: 2014-12-07T02:03:07Z
• Authors: Zs. Dömötör; R. Szemerszky; F. Köteles
• Keywords: Stimulus (psychology)

Impact of 5 mg/kg caffeine, chance receiving caffeine (stimulus expectancies), and expectations effects (response expectancies) on objective (heart rate (HR), systolic/diastolic blood pressure (SBP/DBP), measures heart variability (HRV), reaction time (RT)) subjective variables were investigated in a double-blind, placebo-controlled experiment with no-treatment group. Participants 107 undergraduate university students (mean age 22.3 ± 3.96 years). Consumption had an impact participants' SBP, standard deviation normal heartbeat intervals, HR (decrease), experience 40 minutes later even after controlling for respective baseline values, stimulus response expectancies, habitual consumption. No DBP, high frequency component HRV, the ratio low- high-frequency, RT found. Beyond actual intake, expectancy score was also determinant which refers to placebo total effect. Actual autonomic (SBP, HR) changes somatosensory amplification tendency, however, no significant experience. Placebo plays role caused by consumption but it has variables. Conditional vs deceptive administration (i.e. any assessed variable.