Effects of information on the reinforcing, subjective, and psychomotor effects of nitrous oxide in healthy volunteers

• Published in: Drug and alcohol dependence 1997-11, Vol.48 (2), p.85-95
• Main Authors: Zacny, James P., Cho, Alys M., Toledano, Alicia Y., Galinkin, Jeff, Coalson, Dennis W., Klock, P.Allan, Klafta, Jerome M., Young, Christopher J.
• Format: Article
• Language: English
• Subjects: Administration, Inhalation; Adult; Biological and medical sciences; Choice; Choice Behavior; Drug addictions; Female; Human; Humans; Information; Informed Consent; Instruction; Male; Medical sciences; Mental Competency; Mood; Nitrous oxide; Nitrous Oxide - administration & dosage; Nitrous Oxide - adverse effects; Psychomotor; Psychomotor Disorders - chemically induced; Reinforcement (Psychology); Reinforcing; Subjective; Toxicology
• ISSN: 0376-8716; 1879-0046
• DOI: 10.1016/S0376-8716(97)00114-2

The purpose of this study was to characterize the reinforcing, subjective, and psychomotor effects of nitrous oxide (N 2O) in healthy volunteers who were given different amounts of information regarding the drugs they were being administered in the experiment. A choice procedure was used in which subjects first sampled a placebo and a given concentration of N 2O, and then chose between the two. N 2O concentration varied across the four-session experiment from 10–40%. Besides choice, subjective and psychomotor effects served as dependent measures. In the INFORMED group ( n = 11), subjects were told at the beginning of each sampling trial what concentration of N 2O they were inhaling or whether they were inhaling 100% oxygen (placebo). They were also informed about the prototypic effects of N 2O (e.g. tingling or numbing, euphoria, dysphoria) and oxygen (e.g. no discernible effects). In the NON-INFORMED group ( n = 11), subjects were only told at the beginning of each sampling trial that the drugs they would be inhaling came from one of six classes of drugs. Thirty percent N 2O was chosen by a significantly higher proportion of subjects than expected by chance in the INFORMED group, but not in the NON-INFORMED group. Further, the probability of choosing 20–40% N 2O was higher in the INFORMED group than in the NON-INFORMED group. Subjective effects of N 2O were not affected by the information manipulation. Psychomotor performance at the highest N 2O concentration tested (40%) was impaired to a greater extent in the NON-INFORMED than in the INFORMED group. We conclude that the reinforcing effects of N 2O, and perhaps the impairing effects, can be modulated by telling subjects beforehand that they are inhaling N 2O and what effects they might be expected to experience from the drug.