Objective: Healthy volunteers are involved in stage I of clinical investigations. It appears to be necessary to characterize such subjects more closely. Representing an essential aspect are symptoms giving rise to complaints that are typical side effects of drugs but that often also occur as adverse nondrug reactions. Correlations are supposed to exist between personality, motivation, and emotion of subjects and the incidence of their complaints.
Methods: One hundred thirty medical students answered the "Questionnaire for Side Effects of Drugs" (Reidenberg and Löwenthal, 1968), and they were studied with regard to their personality (Freiburg Personality Inventory), motivation (Motivation Q-Sort) and emotion (State-Trait-Anxiety Inventory).
Results: The most frequent complaints noted in young healthy volunteers who did not take any drugs were fatigue (65%), headache (25%), and nasal congestions (30%). Only 11% of the medical students were free of symptoms, 50% stated that they had one or two symptoms, and 3% had more than six symptoms. Statistically significant, even though weak, correlations existed between the number of symptoms and the personality traits of nervousness and neuroticism, motivation, and trait-anxiety. However, cluster analysis was adopted to form two groups: One subgroup (not nervous, emotionally stable, success-motivated, and not very anxious) that stated less adverse nondrug reactions, and another contrasting subgroup that complained about symptoms more frequently.
Conclusion: It appears that the distribution of the incidence of complaints in a nonselected group of healthy volunteers is not of a random character. The relevance of this finding to stage I clinical trials is evident.