Addict Biol
February 1, 2022
Harriet de Wit, Hanna Molla, Anya K. Bershad et al.
82 citations
The resurgence of interest in using psychedelic drugs, including lysergic acid diethylamide (LSD), in psychiatry has drawn attention to the medically unsupervised practice of 'microdosing'. Thousands of users claim that very low doses of LSD, taken at 3-4-day intervals, improve mood and cognitive function., However, few controlled studies have described the effects of the drug when taken in...
PLoS One
October 25, 2021
Annie Regan, Seth Margolis, Harriet de Wit et al.
18 citations
3,4-Methylenedioxymethamphetamine (MDMA) is a psychostimulant known for producing positive subjective effects and for enhancing social functioning and social connection in both clinical and recreational settings. Over the past two decades, scientists have begun to study the psychological effects of MDMA through rigorous placebo-controlled experimental work. However, most existing studies have...
Psychopharmacology
October 6, 2021
Conor H. Murray, Ilaria Tare, Claire Perry et al.
75 citations
Classical psychedelics, including psilocybin and lysergic acid diethylamide (LSD), are under investigation as potential therapeutic agents in psychiatry. Whereas most studies utilize relatively high doses, there are also reports of beneficial effects of “microdosing,” or repeated use of very low doses of these drugs. The behavioral and neural effects of these low doses are not fully understood....
Nat Med
June 1, 2021
David Nutt, Harriet de Wit
6 citations
Putting the MD back into MDMA.
Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology
October 1, 2020
Kirsten C. S. Adam, Manoj K. Doss, Elisa Pabon et al.
2 citations
With the increasing prevalence of legal cannabis use and availability, there is an urgent need to identify cognitive impairments related to its use. It is widely believed that cannabis, or its main psychoactive component Δ9-tetrahydrocannabinol (THC), impairs working memory, i.e., the ability to temporarily hold information in mind. However, our review of the literature yielded surprisingly...
Neuropsychopharmacology
January 24, 2020
Carla Agurto, Guillermo Cecchi, Raquel Norel et al.
33 citations
Abstract The detection of changes in mental states such as those caused by psychoactive drugs relies on clinical assessments that are inherently subjective. Automated speech analysis may represent a novel method to detect objective markers, which could help improve the characterization of these mental states. In this study, we employed computer-extracted speech features from multiple domains...
Biological psychiatry. Cognitive neuroscience and neuroimaging
2020
Manoj K. Doss, Jessica Weafer, David A Gallo et al.
With the growing acceptance of cannabis use, it is crucial to understand the drug's effects on episodic memory accuracy and distortion. We investigated the impact of the administration of Δ9-tetrahydrocannabinol (THC), the main psychoactive constituent of cannabis, on a context-based memory illusion. In a double-blind, placebo-controlled, within-subjects design, healthy infrequent cannabis...
Biol Psychiatry Cogn Neurosci Neuroimaging
December 20, 2019
Anya K. Bershad, Katrin H. Preller, Royce Lee et al.
95 citations
BackgroundThe practice of "microdosing," or the use of repeated, very low doses of lysergic acid diethylamide (LSD) to improve mood or cognition, has received considerable public attention, but empirical studies are lacking. Controlled studies are needed to investigate both the therapeutic potential and the neurobiological underpinnings of this pharmacologic treatment.MethodsThe present study...
bioRxiv (Cold Spring Harbor Laboratory)
September 23, 2019
Kirsten C. S. Adam, Manoj K. Doss, Elisa Pabon et al.
2 citations
preprint
Abstract With the increasing prevalence of legal cannabis use and availability, there is an urgent need to identify cognitive impairments related to its use. It is widely believed that cannabis, or its main psychoactive component Δ 9 -tetrahydrocannabinol (THC), impairs working memory, i.e., the ability to temporarily hold information in mind. However, our review of the literature yielded...
Journal of psychopharmacology (Oxford, England)
September 1, 2019
Elisa Pabon, Harriet de Wit
Acute consumption of cannabis or its primary psychoactive ingredient ∆9-tetrahydrocannabinol has been shown to impair memory, reaction time, time perception, and attention. However, it is difficult to measure these impairments in a brief test that can be used in a non-laboratory setting. We aim to develop and validate a prototype for a mobile phone application to measure...
Biological Psychiatry
June 3, 2019
Anya K. Bershad, Scott T. Schepers, Michael P. Bremmer et al.
176 citations
BackgroundNumerous anecdotal reports suggest that repeated use of very low doses of lysergic acid diethylamide (LSD), known as microdosing, improves mood and cognitive function. These effects are consistent both with the known actions of LSD on serotonin receptors and with limited evidence that higher doses of LSD (100-200 μg) positively bias emotion processing. Yet, the effects of such...
Psychopharmacology (Berl)
February 1, 2018
H. Valerie Curran, David Nutt, Harriet de Wit
17 citations
Psychedelics and related drugs: therapeutic possibilities, mechanisms and regulation.
Psychopharmacology
July 1, 2017
Anya K. Bershad, Melissa A. Miller, Harriet de Wit
12 citations
Rationale ±3,4-Methylenedioxymethamphetamine (MDMA, “ecstasy”) is a stimulant-psychedelic drug with unique social effects. It may dampen reactivity to negative social stimuli such as social threat and rejection. Perhaps because of these effects, MDMA has shown promise as a treatment for post-traumatic stress disorder (PTSD). However, the effect of single doses of MDMA on responses to an acute...
Journal of Psychopharmacology
August 26, 2016
Anya K. Bershad, Melissa A. Miller, Matthew J. Baggott et al.
104 citations
±3,4-Methylenedioxymethamphetamine (MDMA) is a popular recreational drug that enhances sociability and feelings of closeness with others. These “prosocial” effects appear to motivate the recreational use of MDMA and may also form the basis of its potential as an adjunct to psychotherapy. However, the extent to which MDMA differs from prototypic stimulant drugs, such as dextroamphetamine,...
Social Neuroscience
January 20, 2016
Anya K. Bershad, Jessica Weafer, Matthew G. Kirkpatrick et al.
35 citations
3,4-Methylenedioxymethamphetamine (MDMA, "ecstasy") enhances desire to socialize and feelings of empathy, which are thought to be related to increased oxytocin levels. Thus, variation in the oxytocin receptor gene (OXTR) may influence responses to the drug. Here, we examined the influence of a single OXTR nucleotide polymorphism (SNP) on responses to MDMA in humans. Based on findings that...
Journal of Psychopharmacology
April 29, 2015
Matthew J. Baggott, Matthew G. Kirkpatrick, Gillinder Bedi et al.
69 citations
Rationale: ±3,4-methylenedioxymethamphetamine (MDMA) is widely believed to increase sociability. The drug alters speech production and fluency, and may influence speech content. Here, we investigated the effect of MDMA on speech content, which may reveal how this drug affects social interactions. Method: Thirty-five healthy volunteers with prior MDMA experience completed this two-session,...
Journal of Psychopharmacology
March 4, 2015
Matthew G. Kirkpatrick, Andrew W. Delton, Theresa E. Robertson et al.
86 citations
Background: 3,4-methylenedioxymethamphetamine (MDMA) produces “prosocial” effects that contribute to its recreational use. Few studies have examined the cognitive and behavioral mechanisms by which MDMA produces these effects. Here we examined the effect of MDMA on a specific prosocial effect, i.e. generosity, using a task in which participants make decisions about whether they or another...
The International Journal of Neuropsychopharmacology
December 28, 2014
Stephanie M. Gorka, Daniel A. Fitzgerald, Harriet de Wit et al.
43 citations
BACKGROUND: Δ(9)-Tetrahydrocannabinol has been shown to modulate anxiety and facilitate the extinction of fear by inhibiting amygdala reactivity. Since functional coupling between the amygdala and prefrontal cortex is implicated in affective processes, it is possible that Δ(9)-tetrahydrocannabinol affects amygdala-prefrontal cortex functional connectivity in ways that differ across amygdala...
Psychopharmacology (Berl)
October 5, 2014
Matthew G. Kirkpatrick, Harriet de Wit
43 citations
RationaleThe drug ±3,4-methylenedioxymethamphetamine (MDMA, "ecstasy," "molly") is thought to produce prosocial effects and enhance social interaction. However, in most laboratory studies to date, the participants have been tested under nonsocial conditions, which may not simulate the effects the drug produces in more naturalistic social settings.MethodsHealthy experienced MDMA users...
Psychoneuroendocrinology
April 19, 2014
M. Kirkpatrick, Sunday M. Francis, Royce Lee et al.
106 citations
MDMA (±3,4-methylenedioxymethamphetamine, ‘ecstasy’) is reportedly used recreationally because it increases feelings of sociability and interpersonal closeness. Prior work suggests that the pro-social effects of MDMA may be mediated by release of oxytocin. A direct examination of plasma levels of oxytocin after acute doses of oxytocin and MDMA, in the same individuals, would provide further...
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...
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...
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....