Reliability of symptom reports by healthy volunteers treated with placebo over several time periods

In four test periods (medication-free control, three placebo periods with the suggestion randomised placebo or sedative or stimulant) 78 healthy medical students had to check off on a side-effect questionnaire those symptoms that they had experienced over the previous 72 h (adverse nondrug reactions). In the control period only 14 volunteers (18%) were without symptoms. In the course of 4 weeks this number doubled, and the number of symptoms complained decreased correspondingly, e.g. tiredness, headaches, muscle and joint pains etc. This development is relevant inasmuch as in phase-I studies the well-being of the volunteers is often monitored over protracted periods of time and perhaps decreasing interest or a decreasing motivation must be reckoned with. One or two rounds of tests present special situations, in any case, which cannot be reproduced. As the frequency of the symptoms complained of is modified by the personality structure, balanced groups must be formed for controlled studies. In Phase I trials it may sometimes be useful to characterize the volunteers psychologically.