EFFECT OF DECEPTIVE VERSUS NON-DECEPTIVE PLACEBO ON PSYCHOMOTOR AND COGNITIVE FUNCTIONS IN HEALTHY ADULT HUMAN VOLUNTEERS: AN OPEN-LABEL CROSS-OVER RANDOMIZED CONTROLLED TRIAL

This study was planned to evaluate the effect of a placebo administered with deception vs. without deception on psychomotor and cognitive functions in healthy human volunteers compared to no treatment as placebo responses tend to be circumstantial. An open-label, 3-period, 6-sequence randomized controlled cross-over trial was conducted with 54 participants in a tertiary care center. After the initial screening for eligibility, the patients were randomized into sequences. Psychomotor, executive, and memory function tests were performed before and 30 minutes after the administration of the intervention on three different days (one intervention each day). Participants showed a significant reduction in reaction time in most of the computerized tests for evaluation of psychomotor function (simple reaction time: one hand: 47.15; 95% CI: 30.99 to 63.32; p <0.001, both hands: 63.90; 95%CI: 46.23 to 81.57; p <0.001|| choice reaction time (79.83; 95%CI: 41.27 to 118.40; p<0.001) and digit picture substitution test (182.12; 95% CI: 116.0 to 248.24; p < 0.001)), executive function and memory with deceptive placebo when compared to nondeceptive placebo. No statistical difference in the paper and pencil tests was observed; however, there was a significant reduction in deceptive placebo over nondeceptive placebo or no intervention groups for trail-making tests for the executive functions. No significant difference was observed for motor functions. A deceptive placebo has a significant effect on psychomotor function compared to a nondeceptive placebo and no treatment; thus there could be differences in placebo responses in clinical trial versus clinical practice or double blind versus open label placebo. The calculation of actual drug effect in a clinical trial needs the development of an algorithm balancing for placebo response.