Psychopharmacology
April 12, 2014
Margaret C. Wardle, Harriet de Wit
97 citations
±3,4-Methylenedioxymethamphetamine (MDMA, “ecstasy”) produces “prosocial” effects, such as feelings of empathy and closeness, thought to be important to its abuse and its value in psychotherapy. However, it is not fully understood how MDMA alters basic emotional processes to produce these effects, or whether it produces corresponding changes in actual social behavior. Here, we examined how MDMA...
Social Cognitive and Affective Neuroscience
March 27, 2014
Margaret C. Wardle, Matthew G. Kirkpatrick, Harriet de Wit
52 citations
3,4-Methylenedioxymethamphetamine (MDMA, 'ecstasy') is used recreationally to improve mood and sociability, and has generated clinical interest as a possible adjunct to psychotherapy. One way that MDMA may produce positive 'prosocial' effects is by changing responses to emotional stimuli, especially stimuli with social content. Here, we examined for the first time how MDMA affects subjective...
Psychopharmacology
March 15, 2014
M. Kirkpatrick, Matthew J. Baggott, John Mendelson et al.
78 citations
Several laboratories have conducted placebo-controlled drug challenge studies with 3,4-methylenedioxymethamphetamine (MDMA), providing a unique source of data to examine the reliability of the acute effects of the drug across subject samples and settings. We examined the subjective and physiological responses to the drug across three different laboratories and investigated the influence of...
Pharmacology, Biochemistry, and Behavior
February 2014
Charles G Frye, Margaret C. Wardle, Greg J Norman et al.
3-4-Methylenedioxymethamphetamine (MDMA) increases self-reported positive social feelings and decreases the ability to detect social threat in faces, but its effects on experiences of social acceptance and rejection have not been determined. We examined how an acute dose of MDMA affects subjective and autonomic responses to simulated social acceptance and rejection. We predicted that MDMA would...
Psychopharmacology
October 2012
Jane Metrik, Christopher W Kahler, Brady Reynolds et al.
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...
Journal of Neural Transmission
June 2012
Christine A Rabinak, Chandra Sekhar Sripada, Mike Angstadt et al.
Cannabinoids affect positive and negative affective experience and emotional perception, possibly by modulating limbic brain reactivity. In this double-blind crossover, placebo-controlled functional magnetic resonance imaging study in humans, an acute oral dose of ∆(9)-tetrahydrocannabinol (THC) attenuated subgenual anterior cingulate cortex (sgACC) reactivity during the induction of negative...
Journal of Psychopharmacology
May 13, 2012
Michael E. Ballard, Gillinder Bedi, Harriet de Wit
52 citations
There is growing evidence that drugs of abuse alter processing of emotional information in ways that could be attractive to users. Our recent report that Δ⁹-tetrahydrocannabinol (THC) diminishes amygdalar activation in response to threat-related faces suggests that THC may modify evaluation of emotionally-salient, particularly negative or threatening, stimuli. In this study, we examined the...
Pharmacology, Biochemistry, and Behavior
November 24, 2010
Michael E. Ballard, Harriet de Wit
Rationale: Previous studies examining the combined effects of ethanol and cannabis, or its primary psychoactive ingredient, ∆⁹-tetrahydrocannabinol (THC), have provided mixed results. Data from an in vitro study suggests that combined, sub-threshold doses of these drugs may interact to produce synergistic effects. Very low doses of the two drugs in combination have not been tested in humans....
Experimental and Clinical Psychopharmacology
August 1, 2009
Jane Metrik, Damaris J Rohsenow, Peter M. Monti et al.
Although alcohol and nicotine administration studies have demonstrated that manipulating subjects' expectancies regarding drug content affects drug response, research with marijuana has not adequately studied drug expectancy effects. The present pilot study was the first to evaluate the credibility and effect of expectancy manipulation on subjective measures and smoking patterns using a...
Journal of Neuroscience
March 5, 2008
K. Phan, Mike Angstadt, J. Golden et al.
The cannabinoid (CB) system is a key neurochemical mediator of anxiety and fear learning in both animals and humans. The anxiolytic effects of Δ9-tetrahydrocannabinol (THC), the primary psychoactive ingredient in cannabis, are believed to be mediated through direct and selective agonism of CB1 receptors localized within the basolateral amygdala, a critical brain region for threat perception....
Behavioural Pharmacology
September 1, 2005
Aaron B Ilan, Alan Gevins, Michael J. Coleman et al.
165 citations
This study investigated the contribution of different cannabinoids to the subjective, behavioral and neurophysiological effects of smoked marijuana. Healthy marijuana users (12 men, 11 women) participated in four sessions. They were randomly assigned to a low or a high delta9-tetrahydrocannabinol group (THC; 1.8% versus 3.6%). In the four sessions under blinded conditions subjects smoked...
Neuropsychopharmacology
July 2003
Jennifer S. McDonald, Laura Schleifer, Jerry B Richards et al.
This study investigated the acute effects of delta(9)-tetrahydrocannabinol (THC) on four behavioral measures of impulsivity in recreational marijuana users. Although impulsive behavior has been studied using several different measures of impulsivity, few studies have utilized more than one of these measures on a single cohort. In this study, 37 healthy men and women participated in three...
Drug and Alcohol Dependence
February 1, 1993
Cathleen S. Dohrn, J L Lichtor, Dennis W. Coalson et al.
The subjective, psychomotor and reinforcing effects of nitrous oxide at subanesthetic doses (30% and 40% in oxygen) were determined in normal healthy volunteers using a choice paradigm. Thirty percent nitrous oxide was chosen no more often than oxygen (41.6% choice rate), indicating that, for most of the subjects tested, extended inhalation of this nitrous oxide concentration was no more...
Behavioural Pharmacology
February 1, 1992
Cathleen S. Dohrn, J.L. Lichtor, R.S. Finn et al.
The effects of nitrous oxide at subanesthetic doses (0%, 10%, 20%, and 40% in oxygen) on mood and psychomotor performance were determined in a group of 12 healthy volunteers (six males and six females). A randomized, placebo-controlled, double-blinded, crossover trial of five experimental sessions was used. Effects were measured before, during and after a 30-min inhalation period of the agent,...
Connor J Haggarty, Anya K. Bershad, Mahesh K Kumar et al.
3,4-methylenedioxymethamphetamine (MDMA) has long been used non-medically, and it is currently under investigation for its potential therapeutic benefits. Both uses may be related to its ability to enhance empathy, sociability, emotional processing and its anxiolytic effects. However, the neural mechanisms underlying these effects, and their specificity to MDMA compared to other stimulants, are...
Manoj K. Doss, Harriet de Wit, David A Gallo
preprint
Psychoactive drugs modulate learning and emotional processes in ways that could impact their recreational and medical use. Recent work has revealed how drugs impact different stages of processing emotional episodic memories, including encoding (formation of memory traces), consolidation (stabilization of memory traces), and retrieval (accessing memory traces). Drugs administered before encoding...