Citation

Metrik J, Kahler CW, Reynolds B, McGeary JE, Monti PM, Haney M, de Wit H, Rohsenow DJ. Psychopharmacology 2012; 223(4): 489-499.

Affiliation

Center for Alcohol and Addiction Studies, Brown University, Box G-S121, Providence, RI, 02912, USA, Jane_Metrik@brown.edu.

Copyright

(Copyright © 2012, Holtzbrinck Springer Nature Publishing Group)

DOI

10.1007/s00213-012-2740-y

PMID

22588253

Abstract

RATIONALE: Marijuana is believed to increase impulsivity and risk taking, but the processes whereby it affects such behaviors are not understood. Indeed, either the pharmacologic effect of delta-9-tetrahydrocannabinol (THC) or the expectancy of receiving it may lead to deficits in cognitive processing and increases in risk taking. OBJECTIVES AND METHODS: We examined the relative effects of expecting to receive active marijuana and the pharmacological drug effects using a balanced placebo design. Young adult regular marijuana users (N = 136) were randomly assigned into one of four groups in a two × two instructional set (Told THC vs. Told no THC) by drug administration (smoked marijuana with 2.8 % THC vs. placebo) design. Dependent measures included subjective intoxication, behavioral impulsivity, and decision-making related to risky behaviors. RESULTS: Active THC, regardless of expectancy, impaired inhibition on the Stop Signal and Stroop Color-Word tasks. Expectancy of having smoked THC, regardless of active drug, decreased impulsive decision-making on a delay discounting task among participants reporting no deception and increased perception of sexual risk among women, consistent with a compensatory effect. Expectancy of smoking THC in combination with active THC increased negative perceptions from risky alcohol use. Active drug and expectancy independently increased subjective intoxication. CONCLUSIONS: Results highlight the importance of marijuana expectancy effects as users believing they are smoking marijuana may compensate for expected intoxication effects when engaged in deliberate decision-making by making less impulsive and risky decisions. Effects of marijuana on impulsive disinhibition, by contrast, reflect direct pharmacologic effects for which participants did not compensate.

Language: en