Balanced placebo design with marijuana: pharmacological and expectancy effects on impulsivity and risk taking.
Jane Metrik, Christopher W Kahler, Brady Reynolds, John E McGeary, Peter M. Monti, Margaret Haney, Harriet de Wit, Damaris J Rohsenow
Psychopharmacology October 2012 DOI: 10.1007/s00213-012-2740-y (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Randomized balanced placebo design experiment Peer reviewed |
|---|---|
| Sample size | 136 |
| Population | Young adult regular marijuana users |
| Dose | 2.8% THC |
| Measures | Stop Signal task, Stroop Color-Word task, delay discounting task, subjective intoxication |
| Topics | Cannabis |
| Key findings | Active THC impaired inhibitory control on the Stop Signal and Stroop Color-Word tasks regardless of expectancy, a direct pharmacological effect the authors say participants did not compensate for. Expectancy of having smoked THC, independent of the drug, reduced impulsive decision-making on a delay discounting task among participants reporting no deception and increased perceived sexual risk among women, which the authors interpret as compensation for expected intoxication during deliberate decision-making. |
Abstract
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. 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. 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. 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.
Comparable studies
Other randomized controlled trials on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment Healthy participants | 2012 | Randomized controlled trial | n = 48 |
| Distinct Effects of Δ9-Tetrahydrocannabinol and Cannabidiol on Neural Activation During Emotional Processing Healthy, English-native, right-handed men who had used cannabis 15 times or less in... | 2009 | Double-blind, randomized, placebo-controlled crossover trial | n = 15 |
| Acute Effects of a Single, Oral dose of d9-tetrahydrocannabinol (THC) and Cannabidiol (CBD) Administration in Healthy Volunteers Healthy male subjects | 2012 | Randomized controlled trial | n = 16 |
| Modulation of Mediotemporal and Ventrostriatal Function in Humans by Δ9-Tetrahydrocannabinol Healthy, native English-speaking, right-handed men of white race/ethnicity who had used... | 2009 | Randomized controlled trial | n = 15 |
| Cannabidiol (CBD) content in vaporized cannabis does not prevent tetrahydrocannabinol (THC)-induced impairment of driving and cognition Healthy volunteers with a history of light cannabis use | 2019 | Randomized, double-blind, within-subjects crossover | n = 14 |
Citations in the library
Cited by 22
- Effects of Cannabis on Impulsivity: A Systematic Review of Neuroimaging Findings Current Pharmaceutical Design May 10, 2014
- Cannabis and tolerance: acute drug impairment as a function of cannabis use history Scientific Reports May 26, 2016
- Expectancy Effects in Psychedelic Trials. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging May 1, 2024
- Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users British Journal of Pharmacology October 11, 2013
- Harnessing placebo: Lessons from psychedelic science. Journal of Psychopharmacology June 30, 2023
and 17 more in the library
Cites 8
- Effectiveness of a marijuana expectancy manipulation: Piloting the balanced-placebo design for marijuana. Experimental and Clinical Psychopharmacology August 1, 2009
- Neurocognitive performance during acute THC intoxication in heavy and occasional cannabis users. Journal of Psychopharmacology May 2009
- A study investigating the acute dose-response effects of 13 mg and 17 mg Delta 9- tetrahydrocannabinol on cognitive-motor skills, subjective and autonomic measures in regular users of marijuana. Journal of Psychopharmacology June 2008
- Neural substrates of faulty decision-making in abstinent marijuana users. Neuroimage June 2005
- Acute marijuana effects on human risk taking. Neuropsychopharmacology April 2005
and 3 more in the library