Cannabis and Cannabinoid Research
February 27, 2019
Eef L. Theunissen, Nadia R. P. W. Hutten, Natasha L. Mason et al.
22 citations
Abstract Introduction: Synthetic cannabinoid mixtures have been easily accessible for years, leading to the belief that these products were natural and harmless, which contributed to their popularity. Nevertheless, there are many reports of users ending up in hospital due to severe side effects such as tachycardia, aggression, and psychosis. Controlled studies on the effects of synthetic...
Journal of Psychoactive Drugs
January 24, 2019
Kim P. C. Kuypers, E. B. de Sousa Fernandes Perna, Eef L. Theunissen et al.
13 citations
The phenethylamine 4-fluoroamphetamine (4-FA) is a so-called novel psychoactive substance with a chemical structure resembling that of amphetamine and MDMA. Since 4-FA users report their subjective experience ranges between the effects induced by amphetamine and MDMA, and it is known that both substances can produce an altered state of consciousness, this study tests whether 4-FA induces a...
Human Psychopharmacology Clinical and Experimental
October 25, 2018
Patrick C. Dolder, Elizabeth B. de Sousa Fernandes Perna, Natasha L. Mason et al.
6 citations
OBJECTIVES: 4-Fluoroamphetamine (4-FA) is a novel psychoactive substance with a pharmacological profile and reported subjective effects (e.g., empathy) intermediate between 3,4-methylenedioxymethamphetamine (MDMA) and amphetamine. Studies have shown that MDMA and amphetamine increase emotional empathy without affecting cognitive empathy; MDMA simultaneously leads to elevated levels of oxytocin,...
Psychopharmacology
August 13, 2018
Malin V. Uthaug, Kim van Oorsouw, Kim P. C. Kuypers et al.
213 citations
RATIONALE: Ayahuasca is a psychotropic plant tea from South America used for religious purposes by indigenous people of the Amazon. Increasing evidence indicates that ayahuasca may have therapeutic potential in the treatment of mental health disorders and can enhance mindfulness-related capacities. Most research so far has focused on acute and sub-acute effects of ayahuasca on mental...
Frontiers in Pharmacology
July 6, 2018
Elizabeth B. de Sousa Fernandes Perna, Eef L. Theunissen, Patrick C. Dolder et al.
18 citations
Availability of novel psychoactive substances (NPS) exponentially increased over the last years. Risk evaluations of NPS are hampered by the lack of pharmacological studies in humans on health parameters. The aim of the present study was Tto evaluate safety and neurocognitive function of healthy volunteers (N=12) who received single doses of 100 and 150 mg 4-fluoroamphetamine (4-FA), a...
Psychopharmacology
May 31, 2018
Kim P. C. Kuypers, E. B. de Sousa Fernandes Perna, Patrick C. Dolder et al.
14 citations
BACKGROUND: New psychoactive substances (NPS) are chemical analogues designed to mimic the effects of various classic recreational drugs of abuse including MDMA, LSD, and cannabis. NPS use is associated with concern about the acute and longer-term effects particular substances might have, with abuse and addiction as potential consequences. Impulsivity and sensitivity to the rewarding effects of...
British Journal of Pharmacology
November 22, 2017
Eef L. Theunissen, Nadia R. P. W. Hutten, Natasha L. Mason et al.
38 citations
BACKGROUND AND PURPOSE: Synthetic cannabinoids (often sold as Spice or K2) have become a very popular alternative to cannabis due to their easy access and portrayed safety. Controlled studies on the behavioural effects of synthetic cannabinoids are currently lacking, which hampers risk assessments of these compounds. EXPERIMENTAL APPROACH: This is a first attempt to assess the influence of a...
Scientific Reports
May 26, 2016
Johannes G. Ramaekers, J. H. van Wel, Desirée Spronk et al.
81 citations
Cannabis use history as predictor of neurocognitive response to cannabis intoxication remains subject to scientific and policy debates. The present study assessed the influence of cannabis on neurocognition in cannabis users whose cannabis use history ranged from infrequent to daily use. Drug users (N = 122) received acute doses of cannabis (300 μg/kg THC), cocaine HCl (300 mg) and placebo....
Brain Imaging and Behavior
December 14, 2015
Johannes G. Ramaekers, J. H. van Wel, Desirée Spronk et al.
61 citations
The dopamine β-hydroxylase (DβH) enzyme transforms dopamine into noradrenaline. We hypothesized that individuals with low activity DBH genotypes (rs1611115 CT/TT) are more sensitive to the influence of cannabis and cocaine on cognitive impulse control and functional connectivity in the limbic 'reward' circuit because they experience a drug induced hyperdopaminergic state compared to individuals...
British Journal of Pharmacology
October 11, 2013
Janelle H. P. van Wel, Kim P. C. Kuypers, Eef L. Theunissen et al.
38 citations
BACKGROUND AND PURPOSE: Cannabis is the most popular drug used in the European Union, closely followed by cocaine. Whereas cannabis impairs neurocognitive function in occasional cannabis users, such impairments appear less prominent in heavy users, possibly as a result of tolerance. The present study was designed to assess whether the impairing effects of Δ(9) -tetrahydrocannabinol (THC) in...
Journal of Ethnopharmacology
May 8, 2013
Alexander Paulke, Christian Kremer, Cora Wunder et al.
31 citations
Ethnopharmacological relevanceThe convolvulacea Argyreia nervosa (Burm. f.) is well known as an important medical plant in the traditional Ayurvedic system of medicine and it is used in numerous diseases (e.g. nervousness, bronchitis, tuberculosis, arthritis, and diabetes). Additionally, in the Indian state of Assam and in other regions Argyreia nervosa is part of the traditional tribal...
Psychopharmacology
October 5, 2011
Eef L. Theunissen, Gerold F. Kauert, Stefan W. Toennes et al.
82 citations
RATIONALE: Experienced cannabis users demonstrate tolerance to some of the impairing acute effects of cannabis. OBJECTIVES: The present study investigates whether event-related potentials (ERPs) differ between occasional and heavy cannabis users after acute Δ9-tetrahydrocannabinol (THC) administration, as a result of tolerance. METHODS: Twelve occasional and 12 heavy cannabis users participated...
Psychopharmacology
September 27, 2011
Wendy M. Bosker, Kim P. C. Kuypers, Silke Conen et al.
32 citations
RATIONALE: Experimental research has shown that 3,4-methylenedioxymethamphetamine (MDMA) can improve some psychomotor driving skills when administered during the day. In real life, however, MDMA is taken during the night, and driving may likely occur early in the morning after a night of "raving" and sleep loss. OBJECTIVES: The present study assessed the effects of MDMA on road-tracking and...
Psychopharmacology
October 30, 2010
Johannes G. Ramaekers, Eef L. Theunissen, Marjolein de Brouwer et al.
168 citations
INTRODUCTION: Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce. PURPOSE: The present study was designed to assess...