Acute psychomotor, memory and subjective effects of MDMA and THC co-administration over time in healthy volunteers

Cognitive functioning associated with acute and subacute effects of classic psychedelics and MDMA - a systematic review and meta-analysis

Classic psychedelics and MDMA have a colorful history of recreational use, and both have recently been re-evaluated as tools for the treatment of psychiatric disorders. Several studies have been carried out to assess potential long-term effects of a regular use on cognition, delivering distinct results for psychedelics and MDMA. However, to date knowledge is scarce on cognitive performance during acute effects of those substances. In this systematic review and meta-analysis, we investigate how cognitive functioning is affected by psychedelics and MDMA during the acute drug effects and the sub-acute ("afterglow") window. Our quantitative analyses suggest that acute cognitive performance is differentially affected by psychedelics when compared to MDMA: psychedelics impair attention and executive function, whereas MDMA primarily affects memory, leaving executive functions and attention unaffected. Our qualitative analyses reveal that executive functioning and creativity may be increased during a window of at least 24 h after the acute effects of psychedelics have subsided, whereas no such results have been observed for MDMA. Our findings may contribute to inform recommendations on harm reduction for recreational settings and to help fostering differential approaches for the use of psychedelics and MDMA within a therapeutic framework.

End User Participation in the Development of an Ecological Momentary Intervention to Improve Coping With Cannabis Cravings: Formative Study

BACKGROUND

Cannabis misuse in young adults is a major public health concern. An important predictor of continued use is cannabis craving. Due to the time-varying nature of cravings, brief momentary interventions delivered while cravings are elevated may improve the use of strategies to cope with cravings and reduce cannabis use.

OBJECTIVE

The goal of this manuscript is to describe a formative study to develop coping strategy messages for use in a subsequent intervention.

METHODS

Young adults (aged 19-25 years; n=20) who reported using cannabis >10 of the past 30 days recruited via social media participated in this formative study. Participants rated an initial set of 15 mindfulness and 15 distraction coping strategies on a scale from 1 to 4 (very low degree to very high degree) for clarity, usefulness, and tone. They also provided comments about the content.

RESULTS

Participants found the initial distraction messages slightly clearer than mindfulness (mean 3.5, SD 0.4 and mean 3.4, SD 0.4, respectively), both were comparable in tone (mean 3.2, SD 0.5 and mean 3.2, SD 0.4, respectively), and mindfulness messages were more useful than distraction (mean 3.0, SD 0.5 and mean 2.8, SD 0.6, respectively). Of the 30 messages, 29 received a rating of very low or low (<2) on any domain by >3 participants or received a comment suggesting a change. We revised all these messages based on this feedback, and the participants rated the revised messages approximately 2 weeks later. Participants earned US $10 for completing the first and US $20 for the second survey. The ratings improved on usefulness (especially the distraction items) with very little change in clarity and tone. The top 10 messages of each coping type (mindfulness and distraction) were identified by overall average rating (collapsed across all 3 dimensions: all rated >3.0). The final items were comparable in clarity (distraction mean 3.6, SD 0.4; mindfulness mean 3.6, SD 0.4), tone (distraction mean 3.4, SD 0.4; mindfulness mean 3.4, SD 0.4), and usefulness (distraction mean 3.1, SD 0.5; mindfulness mean 3.2, SD 0.5).

CONCLUSIONS

The inclusion of end users in the formative process of developing these messages was valuable and resulted in improvements to the content of the messages. The majority of the messages were changed in some way including the removal of potentially triggering language. These messages were subsequently used in an ecological momentary intervention.

Effects of psychotropic drugs on ocular parameters relevant to traffic safety: A systematic review

Driving is a complex neurobehavioural task necessitating the rapid selection, uptake, and processing of visual information. Eye movements that are critical for the execution of visually guided behaviour such as driving are also sensitive to the effects of psychotropic substances. The Embase (via Ovid), EBSCOHost, Psynet, Pubmed, Scopus and Web of Science databases were examined from January 01st, 2000 to December 31st, 2021. Study selection, data extraction and Cochrane Risk of Bias (RoB2) assessments were conducted according to PRISMA guidelines. The review was prospectively registered (CRD42021267554). In total, 36 full-text articles examined the effects of six principal psychotropic drug classes on measures of oculomotor parameters relevant to driving. Centrally depressing substances affect oculomotor responses in a dose-dependent manner. Psychostimulants improve maximal speed, but not accuracy, of visual search behaviours. Inhaled Δ-9-tetrahydrocannabinol (THC) increases inattention (saccadic inaccuracy) but does not consistently affect other oculomotor parameters. Alterations to composite ocular parameters due to psychoactive substance usage likely differently compromises performance precision during driving through impaired ability to select and process dynamic visual information.

A Systematic Review of Neurocognitive Effects of Subanesthetic Doses of Intravenous Ketamine in Major Depressive Disorder, Post-Traumatic Stress Disorder, and Healthy Population

BACKGROUND AND OBJECTIVE: Ketamine, a noncompetitive, high-affinity antagonist of the N-methyl-D-aspartate type glutamate receptor, has been investigated for its high efficacy and rapid antidepressant effect and, more recently, for its potential utility in post-traumatic stress disorder (PTSD). The proposal that ketamine's antidepressant and anti-suicidal mechanism may be in part due to its procognitive effect contrasts with the well-established decreased performance on spatial working memory and pattern recognition memory among long-term frequent users. We aimed to review the neurocognitive effects of subanesthetic doses of intravenous ketamine in pharmacological studies among healthy subjects and patients with PTSD or depression.

METHODS

We included studies in English, among healthy adults, or with PTSD or unipolar or bipolar depression where the primary or secondary cognitive outcomes were measured by means of validated neuropsychological test. We excluded studies that reported the use of ketamine only in combination with other drugs or psychotherapy, or studies investigating emotion-laden cognitive functions.

RESULTS

Ketamine administration among patients with depression and possibly with PTSD does not show significant impairment of cognitive functions in the short-term, in contrast with the immediate altered cognitive dysfunction found in healthy subjects. The potential procognitive effects of ketamine seem more pronounced in cognitive domains of executive function, which is in line with the putative molecular, cellular, and synaptic mechanisms of ketamine's therapeutic action.

CONCLUSIONS

The potential procognitive effect of ketamine deserves further exploration. Whether ketamine has transient or sustained neurocognitive benefits beyond its antidepressant effects is unknown. Improved cognition by ketamine might be used to facilitate psychotherapy interventions for PTSD and depression.

The effects of amphetamines alone and in combination with alcohol on functional neurocognition: A systematic review

Due to their desirable synergistic and/or additive pharmacological effects, amphetamines and alcohol are frequently co-consumed; yet, their combined functional neurocognitive effects remain poorly defined. The PubMed, Scopus, SafetyLit, CINAHL Complete and Medline databases were examined from inception to December 2020. Study selection, data extraction and Cochrane Risk of Bias (RoB2) assessments were conducted according to PRISMA guidelines, and the review was registered on the PROSPERO database (CRD42020189168). A total of 39 full-text articles were included which examined the effects of six amphetamine analogues alone (n = 33) and in combination with alcohol (n = 6) on measures of attention, working memory and reaction time. Amphetamine alone produced limited inverted-U shaped improvement in select behavioural domains, particularly among poor baseline performers. Combined amphetamine and alcohol impaired psychomotor speed and motor control comparable to alcohol alone, and co-consumption with high doses of alcohol (0.08 %BAC) protracted behavioural deficits. Co-consumption of amphetamine with high doses of alcohol impairs response discrimination and psychomotor speed, and their combination is not sufficient to overcome alcohol-induced motor impairment.

Eye movements in patients in early psychosis with and without a history of cannabis use

It is unclear whether early psychosis in the context of cannabis use is different from psychosis without cannabis. We investigated this issue by examining whether abnormalities in oculomotor control differ between patients with psychosis with and without a history of cannabis use. We studied four groups: patients in the early phase of psychosis with a history of cannabis use (EPC; n = 28); patients in the early phase of psychosis without (EPNC; n = 25); controls with a history of cannabis use (HCC; n = 16); and controls without (HCNC; n = 22). We studied smooth pursuit eye movements using a stimulus with sinusoidal waveform at three target frequencies (0.2, 0.4 and 0.6 Hz). Participants also performed 40 antisaccade trials. There were no differences between the EPC and EPNC groups in diagnosis, symptom severity or level of functioning. We found evidence for a cannabis effect (χ2 = 23.14, p < 0.001), patient effect (χ2 = 4.84, p = 0.028) and patient × cannabis effect (χ2 = 4.20, p = 0.04) for smooth pursuit velocity gain. There was a large difference between EPC and EPNC (g = 0.76-0.86) with impairment in the non cannabis using group. We found no significant effect for antisaccade error whereas patients had fewer valid trials compared to controls. These data indicate that impairment of smooth pursuit in psychosis is more severe in patients without a history of cannabis use. This is consistent with the notion that the severity of neurobiological alterations in psychosis is lower in patients whose illness developed in the context of cannabis use.

Acute effects of partial CB1 receptor agonists on cognition - A meta-analysis of human studies

BACKGROUND

Impairment in cognition is frequently associated with acute cannabis consumption. However, some questions remain unanswered as to which deficits are most prominent and which demographic groups are most vulnerable.

METHODS

A literature search yielded 52 experimental studies of acute administration of partial CB₁ receptor agonists (i.e. cannabis, THC, and nabilone) that assessed cognitive dysfunction in 1580 healthy volunteers. Effect size estimates were calculated using the Comprehensive Meta-Analysis for the following six cognitive domains: attention, executive functions, impulsivity, speed of processing, verbal learning/memory, and working memory.

RESULTS

There were small-to-moderate impairments across all cognitive domains. Deficits in verbal learning/memory and working memory were more prominent, whereas attention and impulsivity were the least affected. Meta-regression analysis revealed that the greater the male ratio is in a sample, the greater the negative effect of cannabinoids on speed of processing and impulsivity. Analysis of route of administration showed that the deficits in speed of processing were smaller in the oral, relative to smoking, vaping, and intravenous administration studies. A publication bias was observed.

DISCUSSION

Verbal learning/memory and working memory are most prominently affected by acute administration of partial CB₁ receptor agonists. The results are consistent with the residual cognitive effects that have been documented among chronic cannabis users.

Peripheral endocannabinoid concentrations are not associated with verbal memory impairment during MDMA intoxication

BACKGROUND

Preclinical data have suggested involvement of the endocannabinoid (eCB) system in MDMA-induced memory impairment. Clinical research has shown that blockade of the 5-HT2 receptor nulls memory impairment during MDMA intoxication. Interestingly, studies have demonstrated that the eCB and the 5-HT system interact. It was hypothesized that MDMA would cause an increase in eCB concentrations together with a decrease in memory performance, and that combining MDMA with a 5-HT2 receptor blocker ketanserin would lead to a counteraction of the MDMA effects on eCB concentrations and memory.

METHODS

Twenty healthy recreational polydrug users entered a double-blind placebo-controlled within-subject study. Participants received a pre-treatment (ketanserin 40 mg, placebo) followed 30 min later by a treatment (MDMA 75 mg, placebo). Verbal memory was tested by means of a 30-word learning test. Endocannabinoid concentrations (anandamide (2-AG); N-arachidonylethanolamine (AEA)) were assessed in blood at baseline, before (90 min post-treatment) and after cognitive tests (150 min post-treatment).

RESULTS

Findings showed that MDMA impaired memory 90 min post-treatment in the word learning task. This effect was a replication of previous studies using the same dose of MDMA (75 mg) and the same learning paradigm. Contrary to our hypothesis, MDMA did not affect eCB concentrations, nor did ketanserin block MDMA-induced memory impairment. Ketanserin caused an increase in AEA concentrations, 180 min after administration.

CONCLUSION

Current findings suggest that peripherally measured endocannabinoids are not associated with the verbal memory deficit during MDMA intoxication.

TRIAL REGISTRATION NUMBER

NTR3691.

The Discriminative Stimulus Properties of Hallucinogenic and Dissociative Anesthetic Drugs

The subjective effects of drugs are related to the kinds of feelings they produce, such as euphoria or dysphoria. One of the methods that can be used to study these effects is the drug discrimination procedure. Many researchers have been trying to elucidate the mechanisms that underlie the discriminative stimulus properties of abused drugs (e.g., alcohol, psychostimulants, and opioids). Over the past two decades, patterns of drug abuse have changed, so that club/recreational drugs such as phencyclidine (PCP), 3,4-methylenedioxymethamphetamine (MDMA), ketamine, and cannabinoid, which induce perceptual distortions, like hallucinations, are now more commonly abused, especially in younger generations. In particular, the abuse of designer drugs, which aim to mimic the subjective effects of psychostimulants (e.g., MDMA or amphetamines), has been problematic. However, the mechanisms of the discriminative stimulus effects of hallucinogenic and dissociative anesthetic drugs are not yet fully clear. This chapter focuses on recent findings regarding hallucinogenic and dissociative anesthetic drug-induced discriminative stimulus properties in animals.

Conversion factors for assessment of driving impairment after exposure to multiple benzodiazepines/z-hypnotics or opioids

AIMS

Norway has introduced legal concentration limits in blood for 28 non-alcohol drugs in driving under the influence cases. As of 2016 this legislation also regulates the assessment of combined effects of multiple benzodiazepines and opioids. We herein describe the employed methodology for the equivalence tables for concentrations of benzodiazepines/z-hypnotics and opioids implemented in the Norwegian Road Traffic Act.

METHODS

Legislative limits corresponding to impairment at blood alcohol concentrations (BAC) of 0.02%, 0.05% and 0.12% were established for 15 different benzodiazepines and opioids. This was based on a concept of a linear relationship between blood drug concentration and impairment in drug naïve users. Concentration ratios between these drugs were used to establish conversion factors and calculate net impairment using diazepam and morphine equivalents.

RESULTS

Conversion factors were established for 14 benzodiazepines/z-hypnotics (alprazolam, bromazepam, clobazam, clonazepam, etizolam, flunitrazepam, lorazepam, nitrazepam, nordiazepam, oxazepam, phenazepam, temazepam, zolpidem and zopiclone) and two opioids (methadone and oxycodone).

CONCLUSIONS

Conversion factors to calculate diazepam and morphine equivalents for benzodiazepines/z-hypnotics and selected opioids, respectively, have been operative in the Norwegian Road Traffic Act as of February 2016. Calculated equivalents can be applied by the courts to meter out sanctions.

Dorsal hippocampal NMDA receptors mediate the interactive effects of arachidonylcyclopropylamide and MDMA/ecstasy on memory retrieval in rats

A combination of cannabis and ecstasy may change the cognitive functions more than either drug alone. The present study was designed to investigate the possible involvement of dorsal hippocampal NMDA receptors in the interactive effects of arachidonylcyclopropylamide (ACPA) and ecstasy/MDMA on memory retrieval. Adult male Wistar rats were cannulated into the CA1 regions of the dorsal hippocampus (intra-CA1) and memory retrieval was examined using the step-through type of passive avoidance task. Intra-CA1 microinjection of a selective CB1 receptor agonist, ACPA (0.5-4ng/rat) immediately before the testing phase (pre-test), but not after the training phase (post-training), impaired memory retrieval. In addition, pre-test intra-CA1 microinjection of MDMA (0.5-1μg/rat) dose-dependently decreased step-through latency, indicating an amnesic effect of the drug by itself. Interestingly, pre-test microinjection of a higher dose of MDMA into the CA1 regions significantly improved ACPA-induced memory impairment. Moreover, pre-test intra-CA1 microinjection of a selective NMDA receptor antagonist, D-AP5 (1 and 2μg/rat) inhibited the reversal effect of MDMA on the impairment of memory retrieval induced by ACPA. Pre-test intra-CA1 microinjection of the same doses of D-AP5 had no effect on memory retrieval alone. These findings suggest that ACPA or MDMA consumption can induce memory retrieval impairment, while their co-administration improves this amnesic effect through interacting with hippocampal glutamatergic-NMDA receptor mechanism. Thus, it seems that the tendency to abuse cannabis with ecstasy may be for avoiding cognitive dysfunction.

Smoked cannabis' psychomotor and neurocognitive effects in occasional and frequent smokers

Δ9-Tetrahydrocannabinol (THC), the primary psychoactive constituent in cannabis, impairs psychomotor performance, cognition and driving ability; thus, driving under the influence of cannabis is a public safety concern. We documented cannabis' psychomotor, neurocognitive, subjective and physiological effects in occasional and frequent smokers to investigate potential differences between these smokers. Fourteen frequent (≥4x/week) and 11 occasional (<2x/week) cannabis smokers entered a secure research unit ∼19 h prior to smoking one 6.8% THC cigarette. Cognitive and psychomotor performance was evaluated with the critical tracking (CTT), divided attention (DAT), n-back (working memory) and Balloon Analog Risk (BART) (risk-taking) tasks at -1.75, 1.5, 3.5, 5.5 and 22.5 h after starting smoking. GLM (General Linear Model) repeated measures ANOVA was utilized to compare scores. Occasional smokers had significantly more difficulty compensating for CTT tracking error compared with frequent smokers 1.5 h after smoking. Divided attention performance declined significantly especially in occasional smokers, with session × group effects for tracking error, hits, false alarms and reaction time. Cannabis smoking did not elicit session × group effects on the n-back or BART. Controlled cannabis smoking impaired psychomotor function, more so in occasional smokers, suggesting some tolerance to psychomotor impairment in frequent users. These data have implications for cannabis-associated impairment in driving under the influence of cannabis cases.

Resting state functional magnetic resonance imaging reveals distinct brain activity in heavy cannabis users - a multi-voxel pattern analysis

Chronic cannabis use can cause cognitive, perceptual and personality alterations, which are believed to be associated with regional brain changes and possible changes in connectivity between functional regions. This study aims to identify the changes from resting state functional magnetic resonance imaging scans. A two-level multi-voxel pattern analysis was proposed to classify male cannabis users from normal controls. The first level analysis works on a voxel basis and identifies clusters for the input of a second level analysis, which works on the functional connectivity between these regions. We found distinct clusters for male cannabis users in the middle frontal gyrus, precentral gyrus, superior frontal gyrus, posterior cingulate cortex, cerebellum and some other regions. Based on the functional connectivity of these clusters, a high overall accuracy rate of 84-88% in classification accuracy was achieved. High correlations were also found between the overall classification accuracy and Barrett Barrett Impulsiveness Scale factor scores of attention and motor. Our result suggests regional differences in the brains of male cannabis users that span from the cerebellum to the prefrontal cortex, which are associated with differences in functional connectivity.

The effects of nicotine on cognition are dependent on baseline performance

Since cholinergic neurotransmission plays a major role in cognition, stimulation of the nicotinic acetylcholine receptor may be a target for cognitive enhancement. While nicotine improves performance on several cognitive domains, results of individual studies vary. A possible explanation for these findings is that the effect of nicotine administration may be dependent on baseline cognitive function, where subjects with a suboptimal cognitive performance may benefit from nicotine, while subjects who already perform optimally may show a decline in performance after nicotinic stimulation. We conducted a double-blind randomised placebo-controlled crossover trial, examining the effects of placebo, 1, and 2mg of nicotine on cognition in young (n=16, age 18-30 years) and healthy elderly (n=16, age 60-75 years) subjects. We hypothesised that the elderly would benefit more from nicotine compared to young subjects, as normal ageing is associated with decreases in cognitive function. Attention, working memory, visual memory, information-processing speed, psychomotor function, stereotypy, and emotion recognition were assessed. Compared to the young volunteers, the elderly performed significantly worse on psychomotor function and emotion recognition in the placebo condition. Nicotine had no effect in the young volunteers and decreased performance on working memory and visual memory in the elderly. Contrary to our hypothesis, the effect of nicotine was dependent on baseline performance in both the groups, with subjects with lower baseline performance benefiting from nicotine administration, while those with higher baseline performance performed worse after nicotine administration. This suggests that subjects with lower cognitive performance, irrespective of age, may benefit from nicotine.

The acute effects of MDMA and ethanol administration on electrophysiological correlates of performance monitoring in healthy volunteers

RATIONALE

Knowing how commonly used drugs affect performance monitoring is of great importance, because drug use is often associated with compromised behavioral control. Two of the most commonly used recreational drugs in the western world, 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") and ethanol (alcohol), are also often used in combination. The error-related negativity (ERN), correct-related negativity (CRN), and N2 are electrophysiological indices of performance monitoring.

OBJECTIVES

The present study aimed to investigate how ethanol, MDMA, and their co-administration affect performance monitoring as indexed by the electrophysiological correlates.

METHODS

Behavioral and EEG data were obtained from 14 healthy volunteers during execution of a speeded choice-reaction-time task after administration of ethanol, MDMA, and combined ethanol and MDMA, in a double-blind, placebo-controlled, randomized crossover design.

RESULTS

Ethanol significantly reduced ERN amplitudes, while administration of MDMA did not affect the ERN. Co-administration of MDMA and ethanol did not further impair nor ameliorate the effect of ethanol alone. No drug effects on CRN nor N2 were observed.

DISCUSSION

A decreased ERN following ethanol administration is in line with previous work and offers further support for the impairing effects of alcohol intoxication on performance monitoring. This impairment may underlie maladaptive behavior in people who are under influence. Moreover, these data demonstrate for the first time that MDMA does not affect performance monitoring nor does it interact with ethanol in this process. These findings corroborate the notion that MDMA leaves central executive functions relatively unaffected.

Characterizing the cognitive effects of cocaine: a comprehensive review

Understanding the cognitive sequela of repeated cocaine use is a growing area of research and is crucial to the development of cognitive models of addiction. We systematically reviewed all available placebo-controlled and case-controlled studies on the acute and long-term effects of cocaine on cognitive functioning. In order to compare the magnitude of cognitive effects across cognitive domains we conducted several meta-analyses on a subset of data from long-term effect studies. Studies on acute cocaine administration suggest enhancement of response inhibition and psychomotor speed, while all other domains appear to be unaffected or not investigated adequately. Long-term effects of cocaine show a wide array of deteriorated cognitive functions, indicating that long term cocaine use is characterized by a general cognitive impairment across functions, rather than by specific cognitive deficits. Literature on long-term cocaine effects is more substantial than literature on acute effects. This comprehensive review outlines possible dissociations and similarities of acute vs. long-term cocaine effects in the human brain. Atherosclerosis after cocaine exposure may underlie cognitive dysfunction, suggesting involvement of multiple brain areas. Acute drug studies are important to the future development of addiction models.

Effects of cannabis on neurocognitive functioning: recent advances, neurodevelopmental influences, and sex differences

Decades of research have examined the effects of cannabis on neurocognition. Recent advances in this field provide us with a better understanding of how cannabis use influences neurocognition both acutely (during intoxication) and non-acutely (after acute effects subside). Evidence of problems with episodic memory is one of the most consistent findings reported; however, several other neurocognitive domains appear to be adversely affected by cannabis use under various conditions. There is significant variability in findings across studies, thus a discussion of potential moderators is increasingly relevant. The purpose of this review was to 1) provide an update on research of cannabis' acute and non-acute effects on neurocognition, with a focus on findings since 2007 and 2) suggest and discuss how neurodevelopmental issues and sex differences may influence cannabis effects on neurocognition. Finally we discuss how future investigations may lead to better understanding of the complex interplay among cannabis, stages of neurodevelopment, and sex on neurocognitive functioning.

Discriminative stimulus effects of hallucinogenic drugs: a possible relation to reinforcing and aversive effects

The subjective effects of drugs are related to the kinds of feelings they produce, such as euphoria or dysphoria. One of the methods that can be used to study these effects is the drug discrimination procedure. Many researchers are trying to elucidate the mechanisms that underlie the discriminative stimulus effects of abused drugs (e.g., alcohol, psychostimulants, and opioids). Over the past two decades, the patterns of drug abuse have changed, so that club/recreational drugs such as phencyclidine (PCP), 3,4-methylenedioxymethamphetamine (MDMA), lysergic acid diethylamide (LSD), and ketamine, which induce perceptual distortions, like hallucinations, are now more commonly abused, especially in younger generations. However, the mechanisms of the discriminative stimulus effects of hallucinogenic drugs are not yet fully clear. This review will briefly focus on the recent findings regarding hallucinogenic/psychotomimetic drug-induced discriminative stimulus effects in animals. In summary, recent research has demonstrated that there are at least two plausible mechanisms that can explain the cue of the discriminative stimulus effects of hallucinogenic drugs; one is mediated mainly by 5-HT(2) receptors, and the other is mediated through sigma-1 (σ(1))-receptor chaperone regulated by endogenous hallucinogenic ligand.

Dronabinol, a cannabinoid agonist, reduces hair pulling in trichotillomania: a pilot study

RATIONALE

Trichotillomania is characterized by repetitive pulling causing noticeable hair loss. Pharmacological treatment data for trichotillomania are limited.

OBJECTIVE

Dronabinol appears to reduce the exocitotoxic damage caused by glutamate release in the striatum and offers promise in reducing compulsive behavior.

METHODS

Fourteen female subjects (mean age = 33.3  ±  8.9) with DSM-IV trichotillomania were enrolled in a 12-week open-label treatment study of dronabinol (dose ranging from 2.5-15 mg/day). The primary outcome measure was change from baseline to study endpoint on the Massachusetts General Hospital Hair Pulling Scale (MGH-HPS). In order to evaluate effects on cognition, subjects underwent pre- and post-treatment assessments using objective computerized neurocognitive tests. Data were collected from November 2009 to December 2010.

RESULTS

Twelve of the 14 subjects (85.7%) completed the 12-week study. MGH-HPS scores decreased from a mean of 16.5  ±  4.4 at baseline to 8.7  ±  5.5 at study endpoint (p = 0.001). Nine (64.3%) subjects were "responders" (i.e., ≥ 35% reduction on the MGH-HPS and "much or very much improved" Clinical Global Impression scale). The mean effective dose was 11.6  ±  4.1 mg/day. The medication was well-tolerated, with no significant deleterious effects on cognition.

CONCLUSIONS

This study, the first to examine a cannabinoid agonist in the treatment of trichotillomania, found that dronabinol demonstrated statistically significant reductions in trichotillomania symptoms, in the absence of negative cognitive effects. Pharmacological modulation of the cannabinoid system may prove useful in controlling a range of compulsive behaviors. Given the small sample and open-label design, however larger placebo-controlled studies incorporating cognitive measures are warranted.

Δ9-Tetrahydrocannabinol attenuates MDMA-induced hyperthermia in rhesus monkeys

BACKGROUND

Cannabis is commonly consumed by Ecstasy (3,4-methylenedioxymethamphetamine; MDMA) users, including as an intentional strategy to manipulate the drug experience. The most active psychoactive constituent in cannabis, Δ(9)-tetrahydrocannabinol (THC), and other drugs with partial or full agonist activity at the CB(1) receptor, produces a reduction of body temperature in rodents. Reports show that administration of THC can attenuate temperature increases caused by MDMA in mice or rats; however, a recent study in humans shows that THC potentiates MDMA-induced temperature elevations. Relatively little scientific evidence on the thermoregulatory effects of THC in monkeys is available.

METHODS

The body temperature of male rhesus macaques was recorded after challenge with THC (0.1-0.3 mg/kg, i.m.) or combined challenge of THC with the CB(1) receptor antagonist SR141716 (Rimonabant; 0.3 mg/kg, i.m.) or combined challenge of THC (0.1, 0.3 mg/kg, i.m.) with MDMA (1.78 mg/kg p.o.) using minimally-invasive, implanted radiotelemetry techniques.

RESULTS

THC reduced the body temperature of monkeys in a dose-dependent manner with the nadir observed 3-5 h post-injection; however, an attenuation of normal circadian cooling was also produced overnight following dosing. Hypothermia induced by THC (0.3 mg/kg, i.m.) was prevented by Rimonabant (0.3 mg/kg, i.m.). Finally, 0.3 mg/kg THC (i.m.) attenuated the elevation of body temperature produced by MDMA for about 4 h after oral dosing.

CONCLUSIONS

As with rodents THC produces a robust and lasting decrement in the body temperature of rhesus monkeys; this effect is mediated by the CB(1) receptor. THC also protects against the immediate hyperthermic effects of MDMA in monkeys in a dose-dependent manner. Nevertheless, a paradoxical attenuation of circadian cooling overnight after the THC/MDMA combination cautions that longer-term effects may be critical in assessing risks for the recreational user of cannabis in combination with MDMA.

Acute effects of delta-9-tetrahydrocannabinol on performance monitoring in healthy volunteers

Rationale: The error-related negativity (ERN) is a negative event-related potential that occurs immediately after an erroneous response and is thought to reflect human performance monitoring. Delta-9-Tetrahydrocannabinol (THC) administration in healthy volunteers has been linked to impaired performance monitoring in behavioral studies, but to date no studies have examined the effects of cannabinoids on the ERN. Methods: EEG data from 10 healthy volunteers was recorded during execution of a speeded choice-reaction-time task (Flankers task) after administration of THC or placebo vapor in a double-blind randomized crossover design. Results: The findings of this study show that the ERN was significantly reduced after administration of THC. The behavioral outcomes on the Flankers task showed no indications of drug-induced impairments. Discussion: The diminished ERN reflects impairments in the process of performance monitoring. The task design was not optimized to find behavioral effects. The study shows that cannabinoids impair performance monitoring.

Acute effects of MDMA (3,4-methylenedioxymethamphetamine) on EEG oscillations: alone and in combination with ethanol or THC (delta-9-tetrahydrocannabinol)

RATIONALE

Typical users of 3,4-methylenedioxymethamphetamine (MDMA or "ecstasy") are polydrug users, combining MDMA with alcohol or cannabis [most active compound: delta-9-tetrahydrocannabinol (THC)].

OBJECTIVES

The aim of the present study was to investigate whether co-administration of alcohol or THC with MDMA differentially affects ongoing electroencephalogram (EEG) oscillations compared to the administration of each drug alone.

METHODS

In two separate experiments, 16 volunteers received four different drug conditions: (1) MDMA (100 mg); (2) alcohol clamp (blood alcohol concentration = 0.6‰) or THC (inhalation of 4, 6 and 6 mg, interval of 1.5 h); (3) MDMA in combination with alcohol or THC; and (4) placebo. Before and after drug administration, electroencephalography was recorded during an eyes closed resting state.

RESULTS

Theta and alpha power increased after alcohol intake compared to placebo and reduced after MDMA intake. No interaction between alcohol and MDMA was found. Significant MDMA x THC effects for theta and lower-1-alpha power indicated that the power attenuation after the combined intake of MDMA and THC was less than the sum of each drug alone. For the lower-2-alpha band, the intake of MDMA or THC alone did not significantly affect power, but the intake of combined MDMA and THC significantly decreased lower-2-alpha power.

CONCLUSIONS

The present findings indicate that the combined intake of MDMA and THC, but not of MDMA and alcohol, affects ongoing EEG oscillations differently than the sum of either one drug alone. Changes in ongoing EEG oscillations may be related to the impaired task performance that has often been reported after drug intake.