Reinforcing and subjective effects of oral delta 9-THC and smoked marijuana in humans

Cannabinoid Exposure and Subjective Effects of THC and CBD in Edible Cannabis Products

Background: The popularity of edible cannabis products continues to grow in states with legal cannabis access, but few studies have investigated the acute effects of these commercially available products. The present study sought to explore the effects of three commercially available edible products with different levels of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Methods: A sample of regular cannabis users (N=99) were evaluated. Fifty participants completed the study procedures in-person, whereas 49 participants completed the study procedures remotely via Zoom. Subjective effects and plasma cannabinoid levels (in-person participants only) were assessed before and 2 h after participants self-administered one of three products ad libitum: a THC-dominant edible product, a CBD-dominant edible product, or a THC+CBD edible product. Results: At the 2-h post-use assessment, among in-person participants, plasma THC and CBD levels were robustly correlated with self-reported milligrams of THC and CBD consumed, respectively. Across all three conditions, in-person and remote participants experienced (1) an increase in subjective intoxication and elation, (2) a decrease in tension, and (3) no change in paranoia from pre-use to post-use. At post-use, participants who used a CBD product reported less intoxication relative to participants who used a THC+CBD or THC-only product. Participants who used a THC+CBD product reported consuming less THC-and displayed lower plasma THC levels (in-person participants)-relative to participants who used a THC-only product, despite reporting similar levels of positive (intoxication, elation, liking) and psychotomimetic (paranoia, tension) effects. Psychotomimetic effects were very low among both in-person and remote participants across all three conditions, and there were no post-use differences across conditions. Conclusions: Findings suggest that experienced users who consumed a THC+CBD product reported similar levels of positive and psychotomimetic effects relative to those who consumed a THC-only product, despite consuming less THC and displaying lower plasma THC concentrations. Given the potential harms associated with acute cannabis reward and long-term THC exposure, further research is needed to establish whether edible cannabis products with CBD pose less risk to users. Future studies should examine whether these effects generalize to samples of infrequent users, who may have less experience with edible cannabis use. ClinicalTrials.gov ID: NCT03522103.

Regular Use of Cannabis in Female Athletes Is Associated With a Reduction in Early Anaerobic Power Production

ABSTRACT

Lisano, JK, Flores, VA, Kisiolek, JN, and Stewart, LK. Regular use of cannabis in female athletes is associated with a reduction in early anaerobic power production. J Strength Cond Res 37(3): 616-622, 2023-Despite a growing number of claims related to the ability of cannabis use to affect health and performance, there is limited research available, especially in female athletes. This cross-sectional study aimed to determine whether chronic cannabis use in physically active female athletes is related to altered health and performance. Healthy, physically active, female cannabis users (CU: n = 12) and noncannabis users (NU: n = 12) with an average age of 23.8 ± 3.7 years and 19.3 ± 4.2% body fat completed athletic performance and health assessments. Significance was set at alpha = 0.05. The age of onset of regular cannabis use was 20.1 ± 2.8 years in CU with an average duration of cannabis use of 5.8 ± 3.1 years. There were no differences between groups with respect to body size, body composition, pulmonary function, cardiorespiratory function, or muscular strength. Cannabis users produced significantly less power in the first 2 stages of the Wingate assessment, but CU experienced significantly less anaerobic fatigue. Although body composition and cardiovascular fitness were comparable, average C-reactive protein concentration classified CU with higher risk for cardiovascular disease (CVD). Athletes and coaches who rely heavily on anaerobic performance should consider these findings because they indicate that regular cannabis use may affect early power production and CVD risk.

Assessing cognitive behavioral therapy for insomnia in individuals with cannabis use disorder utilizing actigraphy and serum biomarkers: A pilot study

OBJECTIVE/BACKGROUND

This pilot study aims to assess the effect of Cognitive Behavioral Therapy for insomnia (CBTi) in individuals with cannabis use disorder and insomnia. It also aims to investigate the effect of CBTi on levels of serum inflammatory markers in relation to insomnia symptoms.

METHODS/PATIENTS

Individuals with cannabis use disorder and insomnia symptoms were recruited over 18 months. Data collected included demographics, self-reported sleep parameters, and cannabis use. Blood samples were drawn to measure IL-2, IL-6, CRP, and cortisol. Participants completed the Insomnia Severity Index questionnaire (ISI) and the Patient Health Questionnaire-4 (PHQ-4), and they were provided with an actigraphy (wrist) device for 1 week before CBTi and a subsequent week after completing the 4 CBTi sessions.

RESULTS

Nineteen participants were enrolled in the study. The mean ISI score decreased from moderately severe insomnia at baseline to no clinically significant insomnia after CBTi with a sustained decrease at 3- and 6-months follow-up. Actigraphy showed a significant decrease in sleep onset latency (SOL) after CBTi. Three months after CBTi, 80% of participants reported a decrease in their cannabis use. There was also a significant and sustained decrease in mean PHQ-4 scores after CBTi. Although only trending towards significance, the levels of three out of four biomarkers (IL-2, IL-6, CRP) were decreased 6 months after CBTi.

CONCLUSIONS

CBTi is effective as a short- and long-term treatment of insomnia and comorbid anxiety/depression in individuals who regularly use cannabis. A potential added benefit is a reduction in cannabis consumption and inflammatory serum biomarkers.

Elucidation of partial activation of cannabinoid receptor type 2 and identification of potential partial agonists: Molecular dynamics simulation and structure-based virtual screening

Cannabinoid receptor type 2 (CB2R) is a member of the class A G protein-coupled receptor (GPCRs) family and a component of the endocannabinoid system that is modulated by the psychoactive chemical from Cannabis sativa, partial agonist Δ⁹-tetrahydrocannabinol (Δ⁹-THC). Selective activation of CB2R allows for the treatment of inflammatory and immune-related conditions without the psychotropic effects of CB1R. While CB2R-selective agonists are available, CB2R partial agonists are scarce. Hence, the pharmacological difference between CB2R full agonists and partial agonists remains to be deciphered, prompting the search for novel partial agonists. Here, using an induced-fit docking approach, we built a partial agonist Δ⁹-THC bound CB2R system from the inactive CB2R structure (PDB ID: 5ZTY) and performed microsecond molecular dynamics (MD) simulations. The simulations reveal an upward shift of the "toggle switch" W6.48⁽²⁵⁸⁾ and minor outward movement of the transmembrane helix 6 (TM6). Dynamic network model identifies a possible communication path between the ligand and the toggle switch" W6.48⁽²⁵⁸⁾. Furthermore, to identify potential CB2R partial agonists, we conducted structure-based virtual screening of ZINC15 "Druglike" library containing 17,900742 compounds against 3 conformations derived from MD simulation of CB2R complexed with partial agonist Δ⁹-THC using Glide virtual screening protocol comprising various filters with increasing accuracy. Nine diverse compounds predicted to have high MM-GBSA binding energy scores and good ADMET properties (including high gastrointestinal absorption and low toxicity) are proposed as potential CB2R partial agonists.

A naturalistic study of orally administered vs. inhaled legal market cannabis: cannabinoids exposure, intoxication, and impairment

RATIONALE

Published studies examining the effects of cannabis have largely utilized forms of cannabis that are not representative of the legal market products currently available.

OBJECTIVES

The present study aimed to characterize naturalistic use of legal market flower and edible products by examining associations among blood cannabinoids and amount of THC consumed as well as physiological, cognitive, and subjective effects in users of edible and flower forms.

METHOD

Eighty-four participants who used cannabis at least 1 × /week (55 flower cannabis using participants; 29 edible cannabis using participants mean age = 31.95 years, 44% female) participated. At the experimental appointment in our mobile laboratory, participants completed a blood draw to assess plasma cannabinoids, measures of heart rate, subjective drug effects, and cognition both before and after ad libitum use of legal market flower or edible cannabis.

RESULTS

Average self-reported THC consumed was 15.97 mg (SD = 22.40) in edible users and 51.25 mg (SD = 45.23) in flower users. In the edible group, but not the flower group, strong correlations emerged between self-reported ad libitum THC consumed and plasma THC. Plasma THC was significantly higher after use of inhaled cannabis, but similar levels of plasma THC metabolites and similar levels of subjective intoxication and verbal memory impairment were observed in both flower and edible users.

CONCLUSIONS

Findings support strong correlations among ad libitum THC consumed and THC plasma levels after edible cannabis use and suggest few differences in intoxication and impairment between edible and flower cannabis users after ad libitum use. This novel study provides important preliminary data on the pharmacology and effects of legal market edible cannabis.

Do they need to be tested to be deterred? Exploring the impact of exposure to roadside drug testing on drug driving

INTRODUCTION

Maximizing the deterrent effects of Roadside Drug Testing (RDT) operations remains critical for improving road safety. While preliminary research has explored the impact of being tested at RDT sites, there is yet to be an investigation of different types of exposure (e.g., seeing an operation, being tested) and the subsequent relationship(s) with perceptions of certainty of apprehension and future intentions to offend. The overall objective of this research was to explore these relationships with a sample of drug takers.

METHOD

A total of 803 Queensland motorists aged between 16 and 75 (M = 27.12, SD = 13.09) completed an online-based survey, and all reported consuming marijuana, MDMA, and/or methamphetamine at least once in the previous 12 months. A convenience sampling method was utilized (via Facebook).

RESULTS

The drug driving proportion of the sample (58%) reported a total of 30,858 instances of drug driving, or 66 instances on average. Seeing RDT in the previous 12 months (26% of sample) was more common than being tested at RDT (7%). The results indicated that seeing RDT two or more times was related to increased certainty of apprehension (compared to those who had seen it only once or never), although the increase was relatively small. Correlational analyses suggest there were some positive (albeit weak relationships) between exposure to RDT (seen and tested) and past and future offending. However, only three significant predictors of future offending emerged: older age, lower perceptions of apprehension certainty, and greater use of marijuana. Practical Applications: The results illuminate the extent of the drug driving problem and the need for greater resourcing to increase the real threat of detection. While the effect of exposure to enforcement was small, it was positive, incremental and supportive of increased roadside police enforcement as well as further research to quantify such deterrent processes.

A Comparison of Acute Neurocognitive and Psychotomimetic Effects of a Synthetic Cannabinoid and Natural Cannabis at Psychotropic Dose Equivalence

Due to differences in potency, efficacy, and affinity for CB1 receptors, similarities and differences in psychoactive effect profiles of natural cannabis and synthetic cannabinoids (SCs) cannot reliably be derived from equipotent dose comparisons. Instead, the current study proposes to compare the intrinsic psychoactive effects of natural cannabis (THC) and an SC, JWH-018, at psychotropic dose equivalence. Participants from two placebo-controlled studies were matched for their levels of subjective high to compare neurocognitive and psychotomimetic effects of THC and JWH-018. At equal subjective intoxication levels, both drugs impaired psychomotor, divided attention, and impulse control, with no significant difference between the two drugs. Both drugs also caused significant psychotomimetic effects, but dissociative effects were considerably more pronounced for JWH-018 than THC. We conclude that psychotropic dose equivalence provides a uniform approach for comparing the neurocognitive and psychotomimetic profiles of CB1 agonists, which can also be applied to other drug classes.

Effects of cannabidiol in cannabis flower: Implications for harm reduction

Using a federally compatible, naturalistic at-home administration procedure, the present study examined the acute effects of three cannabis flower chemovars with different tetrahydrocannabinol (THC) to cannabidiol (CBD) ratios, in order to test whether chemovars with a higher CBD content produce different effects. Participants were randomly assigned to ad libitum administration of one of three chemovars (THC-dominant: 24% THC, 1% CBD; THC+CBD: 9% THC, 10% CBD; CBD-dominant: 1% THC, 23% CBD); 159 regular cannabis users (male = 94, female = 65) were assessed in a mobile pharmacology lab before, immediately after, and 1 h after ad libitum administration of their assigned chemovar. Plasma cannabinoids as well as positive (e.g., high, elation) and negative (e.g., paranoia and anxiety) subjective effects were assessed at each time points. Participants who used the CBD-dominant and THC + CBD chemovars had significantly less THC and more CBD in plasma samples compared to participants who used the THC-dominant chemovar. Further, the THC + CBD chemovar was associated with similar levels of positive subjective effects, but significantly less paranoia and anxiety, as compared to the THC-dominant chemovar. This is one of the first studies to examine the differential effects of various THC to CBD ratios using chemovars that are widely available in state-regulated markets. Individuals using a THC + CBD chemovar had significantly lower plasma THC concentrations and reported less paranoia and anxiety while also reporting similar positive mood effects as compared to individuals using THC only, which is intriguing from a harm reduction perspective. Further research is needed to clarify the harm reduction potential of CBD in cannabis products.

Assessment of transient dopamine responses to smoked cannabis

BACKGROUND

Dopaminergic mechanisms that may underlie cannabis' reinforcing effects are not well elucidated in humans. This positron emission tomography (PET) imaging study used the dopamine D2/3 receptor antagonist [11C]raclopride and kinetic modelling testing for transient changes in radiotracer uptake to assess the striatal dopamine response to smoked cannabis in a preliminary sample.

METHODS

PET emission data were acquired from regular cannabis users (n = 14; 7 M/7 F; 19-32 years old) over 90 min immediately after [11C]raclopride administration (584 ± 95 MBq) as bolus followed by constant infusion (Kbol = 105 min). Participants smoked a cannabis cigarette, using a paced puff protocol, 35 min after scan start. Plasma concentrations of Δ9-THC and metabolites and ratings of subjective "high" were collected during imaging. Striatal dopamine responses were assessed voxelwise with a kinetic model testing for transient reductions in [11C]raclopride binding, linear-parametric neurotransmitter PET (lp-ntPET) (cerebellum as a reference region).

RESULTS

Cannabis smoking increased plasma Δ9-THC levels (peak: 0-10 min) and subjective high (peak: 0-30 min). Significant clusters (>16 voxels) modeled by transient reductions in [11C]raclopride binding were identified for all 12 analyzed scans. In total, 26 clusters of significant responses to cannabis were detected, of which 16 were located in the ventral striatum, including at least one ventral striatum cluster in 11 of the 12 analyzed scans.

CONCLUSIONS

These preliminary data support the sensitivity of [11C]raclopride PET with analysis of transient changes in radiotracer uptake to detect cannabis smoking-induced dopamine responses. This approach shows future promise to further elucidate roles of mesolimbic dopaminergic signaling in chronic cannabis use. ClinicalTrials.gov Identifier: NCT02817698.

Advancing the science on cannabis concentrates and behavioural health

ISSUES

The Cannabis sativa L. plant contains hundreds of phytocannabinoids, but putatively of highest importance to public health risk is the psychoactive cannabinoid delta-9-tetrahydrocannabinol (THC), which is associated with risk for cannabis use disorder, affective disturbance, cognitive harm and psychomotor impairment. Recently, there has been an increase in the use and availability of concentrated cannabis products (or 'concentrates') that are made by extracting cannabinoids from the plant to form a product with THC concentrations as high as 90-95%. These products are increasingly popular nationwide. The literature on these widely available high potency concentrates is limited and there are many unknowns about their potential harms.

APPROACH

This review covers the state of the research on cannabis concentrates and behavioural health-related outcomes and makes recommendations for advancing the science with studies focused on accurately testing the risks in relation to critical public and behavioural health questions.

KEY FINDINGS

Data point to unique behavioural health implications of concentrate use. However, causal, controlled and representative research on the effects of cannabis concentrates is currently limited.

IMPLICATIONS

Future research is needed to explore chronic, acute and developmental effects of concentrates, as well as effects on pulmonary function. We also highlight the need to explore these relationships in diverse populations.

CONCLUSION

While the literature hints at the potential for these highly potent products to increase cannabis-related behavioural health harms, it is important to carefully design studies that more comprehensively evaluate the impact of concentrates on THC exposure and short- and long-term effects across user groups.

Are the Acute Effects of THC Different in Aging Adults?

In recent years of expanding legalization, older adults have reported the largest increase in cannabis use of any age group. While its use has been studied extensively in young adults, little is known about the effects of THC in older adults and whether the risks of cannabis might be different, particularly concerning intoxication and cognition. The current study investigated whether age is associated with the deleterious effects of THC on cognitive performance and other behavioral measures before and after ad libitum self-administration of three different types of cannabis flower (THC dominant, THC + CBD, and CBD dominant). Age groups consisted of young adults (ages 21–25) and older adults (ages 55–70). Controlling for pre-use scores on all measures, the THC dominant chemovar produced a greater deleterious effect in younger adults compared with older adults in tests of learning and processing speed, whereas there were no differences between old and young in the effects of the other chemovars. In addition, the young group reported greater cannabis craving than the older group after using the THC chemovar. Consistent with some reports in the preclinical literature, the findings suggest that older adults may be less sensitive to the effects of THC on cognitive and affective measures.

The Relevance of Dual Diagnoses among Drug-Dependent Patients with Sleep Disorders

BACKGROUND

Sleep disorders are often associated with drug use. Nearly 70% of patients admitted for detoxification report sleep problems. Dual disorder (DD) is the comorbidity between mental disorders in general and disorders related to psychoactive substance use. The association between substance use and sleep disorders (SD) appears to be bidirectional. Our objective is to analyze the association between sleep disturbance history and drug use pattern (alcohol, cannabis, opioids, and cocaine).

METHODS

Analysis of data in the first interview at the Addictions Unit of the Department of Psychiatry at the University of Salamanca Health Care Complex between October 2017 and January 2020. The sample consists of 398 patients. We studied the association between different variables: origin of patients (Inpatient Dual Diagnosis Detoxification Unit (IDDDU) vs. Outpatient Drug Clinic (ODC), presence of affective disorder, psychotic disorder, type of drug used, and treatment.

RESULTS

Of patients with DD, 62% had more delayed sleep induction, sleep fragmentation, early awakening, and nightmares. Outpatients had more difficulty falling asleep because, in many cases, they had not previously sought any medical assistance. On the other hand, 67% of the patients with insomnia presented depression.

CONCLUSIONS

There is evidence of a harmful association between DD and SD.

Association of Naturalistic Administration of Cannabis Flower and Concentrates With Intoxication and Impairment

IMPORTANCE

The rapidly growing legal cannabis market includes new and highly potent products, the effects of which, to our knowledge, have not previously been examined in biobehavioral research studies because of federal restrictions on cannabis research.

OBJECTIVE

To use federally compatible, observational methods to study high-∆9-tetrahydrocannabinol (THC) legal market forms of cannabis.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study with a between-groups design that was conducted in a community and university setting, cannabis flower users and concentrate users were randomly assigned to higher- vs lower-THC products within user groups. Participants completed a baseline and an experimental mobile laboratory assessment that included 3 points: before, immediately after, and 1 hour after ad libitum legal market flower and concentrate use. Of the 133 individuals enrolled and assessed, 55 regular flower cannabis users (41.4%) and 66 regular concentrate cannabis users (49.6%) complied with the study's cannabis use instructions and had complete data across primary outcomes.

EXPOSURES

Flower users were randomly assigned to use either 16% or 24% THC flower and concentrate users were randomly assigned to use either 70% or 90% THC concentrate that they purchased from a dispensary.

MAIN OUTCOMES AND MEASURES

Primary outcome measures included plasma cannabinoids, subjective drug intoxication, and neurobehavioral tasks testing attention, memory, inhibitory control, and balance.

RESULTS

A total of 121 participants completed the study for analysis: 55 flower users (mean [SD] age, 28.8 [8.1] years; 25 women [46%]) and 66 concentrate users (mean [SD] age, 28.3 [10.4] years; 30 women [45%]). Concentrate users compared with flower users exhibited higher plasma THC levels and 11-hydroxyΔ9-THC (THC's active metabolite) across all points. After ad libitum cannabis administration, mean plasma THC levels were 0.32 (SE = 0.43) μg/mL in concentrate users (to convert to millimoles per liter, multiply by 3.18) and 0.14 (SE = 0.16) μg/mL in flower users. Most neurobehavioral measures were not altered by short-term cannabis consumption. However, delayed verbal memory (F1,203 = 32.31; P < .001) and balance function (F1,203 = 18.88; P < .001) were impaired after use. Differing outcomes for the type of product (flower vs concentrate) or potency within products were not observed.

CONCLUSIONS AND RELEVANCE

This study provides information about the association of pharmacological and neurobehavioral outcomes with legal market cannabis. Short-term use of concentrates was associated with higher levels of THC exposure. Across forms of cannabis and potencies, users' domains of verbal memory and proprioception-focused postural stability were primarily associated with THC administration.

Acute and residual mood and cognitive performance of young adults following smoked cannabis

OBJECTIVES

To examine acute and residual mood and cognitive performance in young adult regular cannabis users following smoked cannabis.

METHODS

Ninety-one healthy young adults completed this double-blind, placebo-controlled, parallel-groups study. Participants were randomized to receive active (12.5% THC) or placebo cannabis with a 2:1 allocation ratio, and mood [Profile of Mood States (POMS)] and cognitive performance [Hopkins Verbal Learning Test - Revised (HVLT-R), Digit Symbol Substitution Test (DSST), Continuous Performance Test (CPT), grooved pegboard (GPB)] were assessed before and 1, 24, and 48 (h) after smoking cannabis ad libitum. High and Low THC groups were based on blood THC concentrations.

RESULTS

One hour after smoking cannabis, compared to Placebo, in both the High and Low THC groups, there were increases in POMS Arousal and Positive Mood, and in the High THC group only, increases in Confusion, Friendliness, and Elation, and a decrease in Fatigue. Increases in Friendliness and Elation in the High THC group remained significant for 24 h. The only significant acute effect of cannabis on cognition was a decrease in the percent of words retained in the HVLT-R in the High THC group compared to Placebo (mean difference = 15.8%, 95% CI = 3.6-28.0%, p = 0.006). Unexpectedly, compared to Placebo, both the High and Low THC groups improved in DSST performance at 48 h (p ≤ 0.016).

CONCLUSIONS

Under the present experimental conditions, in young regular cannabis users, smoking cannabis ad libitum had significant effects on mood, some of which persisted 24 h later, yet minimal effects on cognition, and no evidence of residual cognitive impairment.

Subjective effects of combustible, vaporized, and edible cannabis: Results from a survey of adolescent cannabis users

BACKGROUND

Data from controlled laboratory experiments in adults indicate that the subjective effects of cannabis vary by administration method (e.g., combustible, vaporized). Whether the subjective effects of cannabis experienced in the natural ecology and among adolescents differ by cannabis administration method is unknown. In this observational study, adolescents' retrospective reports of subjective effects after combustible, edible, and vaporized cannabis use were examined.

METHODS

Students from ten public schools in Los Angeles, CA, USA (M[SD] age = 16.1 [.43] years) who reported past 6-month use of combustible, edible, or vaporized cannabis (N = 584) were surveyed on subjective effects experienced after use (yes/no). They were provided with a 12 item self-report checklist of six positive (e.g., relaxed, energetic) and six negative (e.g., drowsy, lazy) subjective effects. For each method of administration, affirmative responses were summed in positive (range: 0-6) and negative (range: 0-6) effect composite scores.

RESULTS

Generalized estimating equations adjusted for demographics and recent cannabis use revealed a graded pattern of differences in positive subjective effects across products, with highest scores for combustible (M[SD] = 3.98[1.76]), followed by edible (M[SD] = 3.58 [2.04]) and vaporized (M[SD] = 3.11 [2.21]) cannabis (all pairwise cross-product contrasts p < .01). Mean negative effect score was highest for edible (M[SD] = 2.27 [1.95]), followed by combustible (M[SD] = 1.94 [1.66]), and vaporized (M[SD] = 1.34 [1.73]) cannabis, respectively (all pairwise contrasts p < .02).

CONCLUSION

Adolescents' reports of subjective effects varied across cannabis administration methods. Combustible cannabis' more desirable subjective effects profile might be indicative of higher abuse liability.

Cannabinoids and the Microbiota-Gut-Brain Axis: Emerging Effects of Cannabidiol and Potential Applications to Alcohol Use Disorders

The endocannabinoid system (ECS) has emerged in recent years as a potential treatment target for alcohol use disorders (AUD). In particular, the nonpsychoactive cannabinoid cannabidiol (CBD) has shown preclinical promise in ameliorating numerous clinical symptoms of AUD. There are several proposed mechanism(s) through which cannabinoids (and CBD in particular) may confer beneficial effects in the context of AUD. First, CBD may directly impact specific brain mechanisms underlying AUD to influence alcohol consumption and the clinical features of AUD. Second, CBD may influence AUD symptoms through its actions across the digestive, immune, and central nervous systems, collectively known as the microbiota-gut-brain axis (MGBA). Notably, emerging work suggests that alcohol and cannabinoids exert opposing effects on the MGBA. Alcohol is linked to immune dysfunction (e.g., chronic systemic inflammation in the brain and periphery) as well as disturbances in gut microbial species (microbiota) and increased intestinal permeability. These MGBA disruptions have been associated with AUD symptoms such as craving and impaired cognitive control. Conversely, existing preclinical data suggest that cannabinoids may confer beneficial effects on the gastrointestinal and immune system, such as reducing intestinal permeability, regulating gut bacteria, and reducing inflammation. Thus, cannabinoids may exert AUD harm-reduction effects, at least in part, through their beneficial actions across the MGBA. This review will provide a brief introduction to the ECS and the MGBA, discuss the effects of cannabinoids (particularly CBD) and alcohol in the brain, gut, and immune system (i.e., across the MGBA), and put forth a theoretical framework to inform future research questions.

A cross-sectional examination of choice and behavior of veterans with access to free medicinal cannabis

Background: With a rise in public pressure to increase veteran access to medicinal cannabis, free cannabis collectives for military veterans are proliferating across the US. Objectives: The aim of the current study was to document which cannabis formulations and routes of administration are chosen by veterans with increased access to cannabis, and to determine whether cannabis is being used as a substitute for other licit and illicit drugs. Method: The current study collected cross-sectional self-report data on cannabis use, cannabinoid constituent composition, primary indication of use, and substitution practices among a sample of 93 US military veterans (84.9% male) with access to free cannabis. Result: Most of the sample reported using cannabinoids as a substitute for either alcohol, tobacco, prescription medications, or illicit substances, reported that they use cannabis frequently (Modal frequency >4x/day, Modal quantity = 5 to 8 grams/week), and primarily select higher-risk cannabis formulations (i.e., high THC/low CBD, smoked). The majority of the sample reported that they use cannabis to self-treat multiple physical and mental health conditions/symptoms. Conclusions: Results of the current study suggest that military Veterans with reduced barriers to access cannabis could be making both helpful and harmful choices regarding their cannabis use. These findings suggest that more guidance on the selection of cannabis-based products in this population is warranted, particularly as barriers to medicinal cannabis access are reduced.

Subjective cannabis effects as part of a developing disorder in adolescents and emerging adults

In light of expanding legalization of cannabis and swelling debate about the potential risks, particularly for younger users, understanding acute cannabis effects among adolescents and emerging adults is more important than ever. Contemporary models of addiction development identify subjective drug responses as central to the developmental unfolding of drug use disorders. Despite this, surprisingly little is known about cannabis's acute subjective effects in human youths. This research utilized ecological momentary assessment (EMA) in the natural environment to identify the typical situational context of cannabis use among 85 frequent cannabis users, ages 15-24 years (M = 19.8, SD = 2.0; 48.2% female). Study aims were to (a) characterize momentary changes in several subjective states (i.e., stimulation, sedation, tension, craving, and high) when not using, just before cannabis use, and after use, and (b) evaluate whether cannabis responses varied with cannabis use disorder (CUD) severity or across the transition from adolescence to emerging adulthood in a correlational manner. Use of cannabis produced measurable reductions in craving and tension, as well as increases in stimulation, sedation, and "high." Participants with more CUD symptoms reported greater relief of craving and increased stimulatory response and high following use. In contrast, emerging adults reported diminished stimulatory response and high following use, relative to adolescents. Results highlight the utility of EMA for characterizing cannabis response as this behavior unfolds in daily life, during a key developmental timeframe in the pathogenesis of cannabis-use pathology. (PsycINFO Database Record

Quantifying cannabis: A field study of marijuana quantity estimation

The assessment of marijuana use quantity poses unique challenges. These challenges have limited research efforts on quantity assessments. However, quantity estimates are critical to detecting associations between marijuana use and outcomes. We examined accuracy of marijuana users' estimations of quantities of marijuana they prepared to ingest and predictors of both how much was prepared for a single dose and the degree of (in)accuracy of participants' estimates. We recruited a sample of 128 regular-to-heavy marijuana users for a field study wherein they prepared and estimated quantities of marijuana flower in a joint or a bowl as well as marijuana concentrate using a dab tool. The vast majority of participants overestimated the quantity of marijuana that they used in their preparations. We failed to find robust predictors of estimation accuracy. Self-reported quantity estimates are inaccurate, which has implications for studying the link between quantity and marijuana use outcomes. (PsycINFO Database Record

A Novel Observational Method for Assessing Acute Responses to Cannabis: Preliminary Validation Using Legal Market Strains

Background: The development of novel cannabis research methods that are compatible with current federal regulations is imperative to conduct studies of the effects of legal market cannabis. There is very little research on higher strength, higher Δ9-tetrahydrocannabinol (THC), which has become increasingly available since legalization. Research on strains containing cannabidiol (CBD), a second primary, but nonpsychotomimetic, cannabinoid, is very limited. Materials and Methods: Using a novel observational methodology, regular cannabis users were asked to use one of two legal market cannabis strains that they purchased from a local dispensary (one strain containing 8% THC and 16% CBD (THC+CBD) and one containing a 17% THC concentration, but no CBD (THC). After using their suggested cannabis strain as they typically would for a 3-day period, participants returned to the laboratory immediately after their final use. Measures included a blood draw to measure cannabinoid blood levels and circulating cytokines, self-reported subjective drug effects, and verbal recall memory. Results: Analysis of CBD/THC concentration levels in the blood following the 3-day strain manipulation suggests that all, but one participant (n=23/24) followed instructions and used their assigned strain. Individuals in the THC group (n=11) smoked no more than their usual amount, and participants who used the THC+CBD (n=12) strain smoked more than their reported usual amount, but did not have significantly different THC+metabolite blood levels from the THC group. The THC+CBD strain was also associated with less desire to smoke, lower levels of subjective drug effects, and lower levels of circulating cytokines (TNF-α, IL-6, and IL-1β) immediately after use. Conclusions: Initial results support the feasibility of this novel observational methodology involving brief manipulation of strain use. Preliminary findings indicate that participants may self-titrate cannabis use based on cannabinoid concentration and the THC+CBD strain was associated with lower levels of cannabis craving, subjective intoxication, and circulating cytokines.

Phytocannabinoids modulate emotional memory processing through interactions with the ventral hippocampus and mesolimbic dopamine system: implications for neuropsychiatric pathology

Growing clinical and preclinical evidence suggests a potential role for the phytocannabinoid cannabidiol (CBD) as a pharmacotherapy for various neuropsychiatric disorders. In contrast, delta-9-tetrahydrocannabinol (THC), the primary psychoactive component in cannabis, is associated with acute and neurodevelopmental propsychotic side effects through its interaction with central cannabinoid type 1 receptors (CB1Rs). CB1R stimulation in the ventral hippocampus (VHipp) potentiates affective memory formation through inputs to the mesolimbic dopamine (DA) system, thereby altering emotional salience attribution. These changes in DA activity and salience attribution, evoked by dysfunctional VHipp regulatory actions and THC exposure, could predispose susceptible individuals to psychotic symptoms. Although THC can accelerate the onset of schizophrenia, CBD displays antipsychotic properties, can prevent the acquisition of emotionally irrelevant memories, and reverses amphetamine-induced neuronal sensitization through selective phosphorylation of the mechanistic target of rapamycin (mTOR) molecular signaling pathway. This review summarizes clinical and preclinical evidence demonstrating that distinct phytocannabinoids act within the VHipp and associated corticolimbic structures to modulate emotional memory processing through changes in mesolimbic DA activity states, salience attribution, and signal transduction pathways associated with schizophrenia-related pathology.

Mechanisms Underlying Sex Differences in Cannabis Use

Purpose of the Review

Cannabis is the most commonly used illicit substance worldwide. In recent decades, highly concentrated products have flooded the market, and prevalence rates have increased. Gender differences exist in cannabis use, as men have higher prevalence of both cannabis use and cannabis use disorder (CUD), while women progress more rapidly from first use to CUD. This paper reviews findings from preclinical and human studies examining the sex-specific neurobiological underpinnings of cannabis use and CUD, and associations with psychiatric symptoms.

Recent Findings

Sex differences exist in the endocannabinoid system, in cannabis exposure effects on brain structure and function, and in the co-occurrence of cannabis use with symptoms of anxiety, depression and schizophrenia. In female cannabis users, anxiety symptoms correlate with larger amygdala volume and social anxiety disorder symptoms correlate with CUD symptoms. Female cannabis users are reported to be especially vulnerable to earlier onset of schizophrenia, and mixed trends emerge in the correlation of depressive symptoms with cannabis exposure in females and males.

Summary

As prevalence of cannabis use may continue to increase given the shifting policy landscape regarding marijuana laws, understanding the neurobiological mechanisms of cannabis exposure in females and males is key. Examining these mechanisms may help inform future research on sex-specific pharmacological and behavioral interventions for women and men with high-risk cannabis use, comorbid psychiatric disease, and CUD.

Placebo Effects of Edible Cannabis: Reported Intoxication Effects at a 30-Minute Delay

Previous research has demonstrated the ability of non-active smoked cannabis cigarettes to induce subjective effects of intoxication (i.e., placebo effect). No studies have been conduced to test whether edible forms of cannabis, which are associated with a significant delay in onset of effect, are able to induce a placebo effect. In the present study, 20 participants were told that they would receive an edible cannabis lollipop containing a high dose of tetrahydrocannabinol (THC), but were instead given a placebo control. Measures of intoxication and mood were taken at baseline, 30 minutes, and 60 minutes post-ingestion of the placebo lollipop. Results of four repeated-measures ANOVAs found significant and quadratic changes across time in cannabis (ARCI m-scale) intoxication (F(2,18) = 4.90, p = .01, η² = .22) and negative mood (F(2,18) = 3.99, p = .05, η² = .19). Changes in positive mood and the overall measure of general intoxication (ARCI) failed to reach significance. The present study provides preliminary evidence that a placebo effect can be induced with inert edible agents when participants are told that they are receiving active THC. This is the first known study to demonstrate an edible cannabis intoxication placebo effect.

Subjective and physiological effects, and expired carbon monoxide concentrations in frequent and occasional cannabis smokers following smoked, vaporized, and oral cannabis administration

BACKGROUND

Although smoking is the most common cannabis administration route, vaporization and consumption of cannabis edibles are common. Few studies directly compare cannabis' subjective and physiological effects following multiple administration routes.

METHODS

Subjective and physiological effects, and expired carbon monoxide (CO) were evaluated in frequent and occasional cannabis users following placebo (0.001% Δ⁹-tetrahydrocannabinol [THC]), smoked, vaporized, and oral cannabis (6.9% THC, ∼54mg).

RESULTS

Participants' subjective ratings were significantly elevated compared to placebo after smoking and vaporization, while only occasional smokers' ratings were significantly elevated compared to placebo after oral dosing. Frequent smokers' maximum ratings were significantly different between inhaled and oral routes, while no differences in occasional smokers' maximum ratings between active routes were observed. Additionally, heart rate increases above baseline 0.5h after smoking (mean 12.2bpm) and vaporization (10.7bpm), and at 1.5h (13.0bpm) and 3h (10.2bpm) after oral dosing were significantly greater than changes after placebo, with no differences between frequent and occasional smokers. Finally, smoking produced significantly increased expired CO concentrations 0.25-6h post-dose compared to vaporization.

CONCLUSIONS

All participants had significant elevations in subjective effects after smoking and vaporization, but only occasional smokers after oral cannabis, indicating partial tolerance to subjective effects with frequent exposure. There were no differences in occasional smokers' maximum subjective ratings across the three active administration routes. Vaporized cannabis is an attractive alternative for medicinal administrations over smoking or oral routes; effects occur quickly and doses can be titrated with minimal CO exposure. These results have strong implications for safety and abuse liability assessments.

Cannabidiol in medical marijuana: Research vistas and potential opportunities

The high and increasing prevalence of medical marijuana consumption in the general population invites the need for quality evidence regarding its safety and efficacy. Herein, we synthesize extant literature pertaining to the phytocannabinoid cannabidiol (CBD) and its brain effects. The principle phytocannabinoid Δ⁹-tetrahydrocannabinol (Δ⁹-THC) and CBD are the major pharmacologically active cannabinoids. The effect of CBD on brain systems as well as on phenomenological measures (e.g. cognitive function) are distinct and in many cases opposite to that of Δ⁹-THC. Cannabidiol is without euphoriant properties, and exerts antipsychotic, anxiolytic, anti-seizure, as well as anti-inflammatory properties. It is essential to parcellate phytocannabinoids into their constituent moieties as the most abundant cannabinoid have differential effects on physiologic systems in psychopathology measures. Disparate findings and reports related to effects of cannabis consumption reflect differential relative concentration of Δ⁹-THC and CBD. Existing literature, notwithstanding its deficiencies, provides empirical support for the hypothesis that CBD may exert beneficial effects on brain effector systems/substrates subserving domain-based phenomenology. Interventional studies with purified CBD are warranted with a call to target-engagement proof-of-principle studies using the research domain criteria (RDoC) framework.

Separate and combined effects of gabapentin and [INCREMENT]9-tetrahydrocannabinol in humans discriminating [INCREMENT]9-tetrahydrocannabinol

The aim of the present study was to examine a potential mechanism of action of gabapentin to manage cannabis-use disorders by determining the interoceptive effects of gabapentin in cannabis users discriminating [INCREMENT]-tetrahydrocannabinol ([INCREMENT]-THC) using a pharmacologically selective drug-discrimination procedure. Eight cannabis users learned to discriminate 30 mg oral [INCREMENT]-THC from placebo and then received gabapentin (600 and 1200 mg), [INCREMENT]-THC (5, 15, and 30 mg), and placebo alone and in combination. Self-report, task performance, and physiological measures were also collected. [INCREMENT]-THC served as a discriminative stimulus, produced positive subjective effects, elevated heart rate, and impaired psychomotor performance. Both doses of gabapentin substituted for the [INCREMENT]-THC discriminative stimulus and engendered subjective and performance-impairing effects that overlapped with those of [INCREMENT]-THC when administered alone. When administered concurrently, gabapentin shifted the discriminative-stimulus effects of [INCREMENT]-THC leftward/upward, and combinations of [INCREMENT]-THC and gabapentin generally produced larger effects on cannabinoid-sensitive outcomes relative to [INCREMENT]-THC alone. These results suggest that one mechanism by which gabapentin might facilitate cannabis abstinence is by producing effects that overlap with those of cannabinoids.

Preclinical studies on the reinforcing effects of cannabinoids. A tribute to the scientific research of Dr. Steve Goldberg

RATIONALE

The reinforcing effects of most abused drugs have been consistently demonstrated and studied in animal models, although those of marijuana were not, until the demonstration 15 years ago that delta-9-tetrahydrocannabinol (THC) could serve as a reinforcer in self-administration (SA) procedures in squirrel monkeys. Until then, those effects were inferred using indirect assessments.

OBJECTIVES

The aim of this manuscript is to review the primary preclinical procedures used to indirectly and directly infer reinforcing effects of cannabinoid drugs.

METHODS

Results will be reviewed from studies of cannabinoid discrimination, intracranial self-stimulation (ICSS), conditioned place preference (CPP), as well as change in levels of dopamine assessed in brain areas related to reinforcement, and finally from self-administration procedures. For each procedure, an evaluation will be made of the predictive validity in detecting the potential abuse liability of cannabinoids based on seminal papers, with the addition of selected reports from more recent years especially those from Dr. Goldberg's research group.

RESULTS AND CONCLUSIONS

ICSS and CPP do not provide consistent results for the assessment of potential for abuse of cannabinoids. However, drug discrimination and neurochemistry procedures appear to detect potential for abuse of cannabinoids, as well as several novel "designer cannabinoid drugs." Though after 15 years transfer of the self-administration model of marijuana abuse from squirrel monkeys to other species remains somewhat problematic, studies with the former species have substantially advanced the field, and several reports have been published with consistent self-administration of cannabinoid agonists in rodents.

Sleep abnormalities associated with alcohol, cannabis, cocaine, and opiate use: a comprehensive review

Sleep abnormalities are associated with acute and chronic use of addictive substances. Although sleep complaints associated with use and abstinence from addictive substances are widely recognized, familiarity with the underlying sleep abnormalities is often lacking, despite evidence that these sleep abnormalities may be recalcitrant and impede good outcomes. Substantial research has now characterized the abnormalities associated with acute and chronic use of alcohol, cannabis, cocaine, and opiates. This review summarizes this research and discusses the clinical implications of sleep abnormalities in the treatment of substance use disorders.

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.

The subjective psychoactive effects of oral dronabinol studied in a randomized, controlled crossover clinical trial for pain

BACKGROUND

Many cannabinoid medications are approved in North America or in phase III trials, such as dronabinol, nabilone, or nabiximols. Little is known about their subjective psychoactive effects when used for pain management. We hypothesized that when used for pain, dronabinol has psychoactive effects in a dose-response relationship, whose peak effects are comparable with smoking marijuana.

METHODS

This was a randomized controlled trial of single dose placebo, 10 or 20 mg dronabinol in 30 chronic noncancer pain patients taking opioids and not using marijuana. Participants completed the Addiction Research Center Inventory (ARCI) hourly for 8 hours during 3 monitored sessions. Comparison sample was the ARCI ratings in participants with no pain (N=20), monitored every 30 minutes after smoking a 1.99% THC (low) and a 3.51% (high strength) marijuana cigarette.

RESULTS

The 10 and 20 mg dronabinol doses had significantly elevated scores over time on 4/5 subscales versus placebo (P<0.05). Average daily morphine use, total pain relief (TOTPAR), age, sex, and baseline pain level were not significant covariates. ARCI peak effects at 2 hours were similar to peak effects of smoked marijuana at 30 minutes (P=0.80, 10 mg=low strength, 20 mg=high strength).

CONCLUSIONS

In pain patients, oral dronabinol has similar psychoactive effects to smoking marijuana. This risk must be considered in any decision to prescribe cannabinoid medications for pain.

An exploratory study of the combined effects of orally administered methylphenidate and delta-9-tetrahydrocannabinol (THC) on cardiovascular function, subjective effects, and performance in healthy adults

Methylphenidate (MPH) is commonly prescribed for the treatment of Attention Deficit Hyperactivity Disorder (ADHD), and is often used illicitly by young adults. Illicit users often coadminister MPH with marijuana. Little is known about physiologic and subjective effects of these substances used in combination. In this double-blind, cross-over experiment, sixteen healthy adult subjects free from psychiatric illness (including ADHD) and reporting modest levels of marijuana use participated in 6 experimental sessions wherein all combinations of placebo or 10mg oral doses of delta-9-tetrahydocannibinol (THC); and 0mg, 10mg and 40 mg of MPH were administered. Sessions were separated by at least 48 hours. Vital signs, subjective effects, and performance measure were collected. THC and MPH showed additive effects on heart rate and rate pressure product (e.g., peak heart rate for 10mg THC+0mg, 10mg, and 40 mg MPH=89.1, 95.9, 102.0 beats/min, respectively). Main effects of THC and MPH were also observed on a range of subjective measures of drug effects, and significant THC dose × MPH dose interactions were found on measures of "Feel Drug," "Good Effects," and "Take Drug Again." THC increased commission errors on a continuous performance test (CPT) and MPH reduced reaction time variability on this measure. Effects of THC, MPH, and their combination were variable on a measure of working memory (n-back task), though in general, MPH decreased reaction times and THC mitigated these effects. These results suggest that the combination of low to moderate doses of MPH and THC produces unique effects on cardiovascular function, subjective effects and performance measures.

Acute effects of THC on time perception in frequent and infrequent cannabis users

RATIONALE

Cannabinoids have been shown to alter time perception, but existing literature has several limitations. Few studies have included both time estimation and production tasks, few control for subvocal counting, most had small sample sizes, some did not record subjects' cannabis use, many tested only one dose, and used either oral or inhaled administration of Δ⁹-tetrahydrocannabinol (THC), leading to variable pharmacokinetics, and some used whole-plant cannabis containing cannabinoids other than THC. Our study attempted to address these limitations.

OBJECTIVES

This study aims to characterize the acute effects of THC and frequent cannabis use on seconds-range time perception. THC was hypothesized to produce transient, dose-related time overestimation and underproduction. Frequent cannabis smokers were hypothesized to show blunted responses to these alterations.

METHODS

IV THC was administered at doses from 0.015 to 0.05 mg/kg to 44 subjects who participated in several double-blind, randomized, counterbalanced, crossover, placebo-controlled studies. Visual time estimation and production tasks in the seconds range were presented to subjects three times on each test day.

RESULTS

All doses induced time overestimation and underproduction. Chronic cannabis use had no effect on baseline time perception. While infrequent/nonsmokers showed temporal overestimation at medium and high doses and temporal underproduction at all doses, frequent cannabis users showed no differences. THC effects on time perception were not dose related.

CONCLUSIONS

A psychoactive dose of THC increases internal clock speed as indicated by time overestimation and underproduction. This effect is not dose related and is blunted in chronic cannabis smokers who did not otherwise have altered baseline time perception.

The dose effects of short-term dronabinol (oral THC) maintenance in daily cannabis users

BACKGROUND

Prior studies have separately examined the effects of dronabinol (oral THC) on cannabis withdrawal, cognitive performance, and the acute effects of smoked cannabis. A single study examining these clinically relevant domains would benefit the continued evaluation of dronabinol as a potential medication for the treatment of cannabis use disorders.

METHODS

Thirteen daily cannabis smokers completed a within-subject crossover study and received 0, 30, 60 and 120mg dronabinol per day for 5 consecutive days. Vital signs and subjective ratings of cannabis withdrawal, craving and sleep were obtained daily; outcomes under active dose conditions were compared to those obtained under placebo dosing. On the 5th day of medication maintenance, participants completed a comprehensive cognitive performance battery and then smoked five puffs of cannabis for subjective effects evaluation. Each dronabinol maintenance period occurred in a counterbalanced order and was separated by 9 days of ad libitum cannabis use.

RESULTS

Dronabinol dose-dependently attenuated cannabis withdrawal and resulted in few adverse side effects or decrements in cognitive performance. Surprisingly, dronabinol did not alter the subjective effects of smoked cannabis, but cannabis-induced increases in heart rate were attenuated by the 60 and 120mg doses.

CONCLUSIONS

Dronabinol's ability to dose-dependently suppress cannabis withdrawal may be therapeutically beneficial to individuals trying to stop cannabis use. The absence of gross cognitive impairment or side effects in this study supports safety of doses up to 120mg/day. Continued evaluation of dronabinol in targeted clinical studies of cannabis treatment, using an expanded range of doses, is warranted.

Human abuse potential and cognitive effects of taranabant, a cannabinoid 1 receptor inverse agonist: a randomized, double-blind, placebo- and active-controlled, crossover study in recreational polydrug users

INTRODUCTION

Taranabant is a cannabinoid 1 receptor inverse agonist that was in development for treatment of obesity. Because of central nervous system effects, the study was performed to assess the abuse potential and cognitive effects of taranabant in recreational polydrug users compared with phentermine, dronabinol, and placebo.

METHODS

Stimulant- and cannabis-experienced polydrug users (N = 30) were randomized in a double-blind crossover study to receive taranabant 2, 4, 10, and 20 mg; phentermine 45 and 90 mg; dronabinol 20 mg; and placebo. Subjective and neurocognitive measures were administered for 24 hours, and peak/peak change from baseline effects were analyzed using a linear mixed-effects model.

RESULTS

Phentermine 45 and 90 mg showed abuse-related subjective effects versus placebo, including drug liking, overall drug liking, and other positive/stimulant effects, whereas dronabinol 20 mg showed abuse-related positive, cannabis-like, and sedative effects. Taranabant was not significantly different from placebo on most of the subjective measures other than negative/dysphoric effects at the highest dose, and its effects were significantly less pronounced relative to phentermine and dronabinol on most measures. Phentermine improved cognitive/motor performance and dronabinol impaired motor/cognitive performance on some measures, whereas taranabant 4 and 20 mg had minor impairment effects on manual tracking.

CONCLUSIONS

The phentermine and dronabinol results demonstrate the validity and sensitivity of the study. Taranabant did not consistently show stimulant/cannabis-like effects or abuse potential in recreational polydrug users, indicating that cannabinoid 1 receptor inverse agonists/antagonists are unlikely to be recreationally abused.

Psychomotor performance, subjective and physiological effects and whole blood Δ⁹-tetrahydrocannabinol concentrations in heavy, chronic cannabis smokers following acute smoked cannabis

Δ⁹-Tetrahydrocannabinol (THC) is the illicit drug most frequently observed in accident and driving under the influence of drugs investigations. Whole blood is often the only available specimen collected during such investigations, yet few studies have examined relationships between cannabis effects and whole blood concentrations following cannabis smoking. Nine male and one female heavy, chronic cannabis smokers resided on a closed research unit and smoked ad libitum one 6.8% THC cannabis cigarette. THC, 11-hydroxy-THC and 11-nor-9-carboxy-THC were quantified in whole blood and plasma. Assessments were performed before and up to 6 h after smoking, including subjective [visual analog scales (VAS) and Likert scales], physiological (heart rate, blood pressure and respirations) and psychomotor (critical-tracking and divided-attention tasks) measures. THC significantly increased VAS responses and heart rate, with concentration-effect curves demonstrating counter-clockwise hysteresis. No significant differences were observed for critical-tracking or divided-attention task performance in this cohort of heavy, chronic cannabis smokers. The cannabis influence factor was not suitable for quantifying psychomotor impairment following cannabis consumption and was not precise enough to determine recent cannabis use with accuracy. These data inform our understanding of impairment and subjective effects following acute smoked cannabis and interpretation of whole blood cannabinoid concentrations in forensic investigations.

Increased blood pressure after abrupt cessation of daily cannabis use

OBJECTIVE

Cannabis is the most widely used illicit drug. Acute cannabis administration increases blood pressure (BP) and heart rate and tolerance develops to these effects with heavy use. A valid and reliable withdrawal syndrome occurs in most daily users, but few studies have assessed the cardiovascular effects of withdrawal. The objective of this report is to describe unexpected changes in cardiovascular function during brief periods of supervised cannabis use and abstinence in daily cannabis users.

METHODS

A within-subjects ABAC crossover study in which inpatient volunteers smoked cannabis ad libitum (A), and abstained from cannabis (B/C). Vital signs were obtained 3 times daily during 11 inpatient days for 13 daily cannabis users (11 men, 8 African American).

RESULTS

BP increased significantly during periods of cannabis abstinence compared with periods of cannabis use. The magnitude of increase was substantial in a subset (N = 6) of participants, with mean increases of up to 22.8 mm Hg systolic and 12.3 mm Hg diastolic BP observed. A main effect of heart rate was not observed. Secondary analysis limited to morning assessments suggested that resting heart rate increased during abstinence, but the magnitude of this effect was not clinically significant.

CONCLUSIONS

Abrupt cessation of heavy cannabis use may cause clinically significant increases in BP in a subset of users. BP should be monitored among those attempting to reduce or quit frequent cannabis use, particularly those with preexisting hypertension. The time course of this effect is currently unknown and requires further study.

A randomized, double-blind, placebo-controlled, crossover study to evaluate the subjective abuse potential and cognitive effects of nabiximols oromucosal spray in subjects with a history of recreational cannabis use

OBJECTIVE

This study aimed to evaluate the abuse potential and cognitive effects of nabiximols (Sativex, GW Pharma Ltd. Salisbury, UK), an oromucosal spray primarily containing delta‐9‐tetrahydrocannabinol (THC) and cannabidiol (CBD).

METHODS

This was a single‐dose, randomized, double‐blind, crossover study comparing nabiximols (4, 8, and 16 consecutive sprays: 10.8, 21.6, and 43.2 mg THC, respectively) with dronabinol 20 and 40 mg (synthetic THC: Marinol, Solvay Pharmaceuticals, Brussels, Belgium) and matching placebos in 23 recreational cannabis users. Subjective and cognitive/psychomotor measures were administered over 24 h post‐dose.

RESULTS

Dronabinol was significantly different from placebo on abuse potential measures, thereby confirming study validity. Nabiximols 10.8 mg was not significantly different from placebo on primary measures but was different on some secondary measures. Nabiximols 21.6 mg was significantly greater than placebo on some primary/secondary measures, whereas nabiximols 43.2 mg showed significant effects on most measures. Nabiximols 10.8 mg was significantly lower than dronabinol doses on most measures ( p < 0.05). Dronabinol 20 mg effects were numerically higher than nabiximols 21.6 mg but were statistically significant only for some measures. Dronabinol 40 mg and nabiximols 43.2 mg were generally not statistically different.

CONCLUSIONS

Both dronabinol and nabiximols had significant abuse potential compared with placebo at higher doses. Nabiximols showed similar or slightly less abuse potential compared with dronabinol. Therefore, the abuse potential of nabiximols should be no higher than that of dronabinol.

Subjective and physiological effects after controlled Sativex and oral THC administration

Sativex is a cannabis-plant extract delivering nearly 1:1 Δ(9)-tetrahydrocannabinol (THC) and cannabidiol (CBD) by oromucosal spray. It has been suggested that CBD attenuates THC-induced tachycardia, anxiety, and euphoria. In this study, pharmacodynamic effects were compared over 10.5 h in nine cannabis smokers randomly assigned to receive placebo, 5 and 15 mg oral synthetic THC, and low (5.4 mg THC, 5.0 mg CBD) and high (16.2 mg THC, 15.0 mg CBD) doses of Sativex. At therapeutic doses, no substantial CBD-induced modulation of THC's effects was evident. Oral THC and Sativex produced similar, clinically insignificant increases in heart rate, anxiety, and "good drug effects" with no serious adverse events. Oral and oromucosal THC have slower absorption, lower rate of THC delivery to the brain, and fewer associated adverse events as compared with smoked cannabis. These results indicate that Sativex has a pharmacodynamic safety profile comparable to that of oral THC at low, therapeutic doses.

Smoked cannabis for chronic neuropathic pain: a randomized controlled trial

BACKGROUND

Chronic neuropathic pain affects 1%-2% of the adult population and is often refractory to standard pharmacologic treatment. Patients with chronic pain have reported using smoked cannabis to relieve pain, improve sleep and improve mood.

METHODS

Adults with post-traumatic or postsurgical neuropathic pain were randomly assigned to receive cannabis at four potencies (0%, 2.5%, 6% and 9.4% tetrahydrocannabinol) over four 14-day periods in a crossover trial. Participants inhaled a single 25-mg dose through a pipe three times daily for the first five days in each cycle, followed by a nine-day washout period. Daily average pain intensity was measured using an 11-point numeric rating scale. We recorded effects on mood, sleep and quality of life, as well as adverse events.

RESULTS

We recruited 23 participants (mean age 45.4 [standard deviation 12.3] years, 12 women [52%]), of whom 21 completed the trial. The average daily pain intensity, measured on the 11-point numeric rating scale, was lower on the prespecified primary contrast of 9.4% v. 0% tetrahydrocannabinol (5.4 v. 6.1, respectively; difference = 0.7, 95% confidence interval [CI] 0.02-1.4). Preparations with intermediate potency yielded intermediate but nonsignificant degrees of relief. Participants receiving 9.4% tetrahydrocannabinol reported improved ability to fall asleep (easier, p = 0.001; faster, p < 0.001; more drowsy, p = 0.003) and improved quality of sleep (less wakefulness, p = 0.01) relative to 0% tetrahydrocannabinol. We found no differences in mood or quality of life. The most common drug-related adverse events during the period when participants received 9.4% tetrahydrocannabinol were headache, dry eyes, burning sensation in areas of neuropathic pain, dizziness, numbness and cough.

CONCLUSION

A single inhalation of 25 mg of 9.4% tetrahydrocannabinol herbal cannabis three times daily for five days reduced the intensity of pain, improved sleep and was well tolerated. Further long-term safety and efficacy studies are indicated. (International Standard Randomised Controlled Trial Register no. ISRCTN68314063).

Cannabidiol attenuates the appetitive effects of Delta 9-tetrahydrocannabinol in humans smoking their chosen cannabis

Worldwide cannabis dependence is increasing, as is the concentration of Delta(9)-tetrahydrocannabinol (THC) in street cannabis. At the same time, the concentration of the second most abundant cannabinoid in street cannabis, cannabidiol (CBD), is decreasing. These two cannabinoids have opposing effects both pharmacologically and behaviorally when administered in the laboratory. No research has yet examined how the ratio of these constituents impacts on the appetitive/reinforcing effects of cannabis in humans. A total of 94 cannabis users were tested 7 days apart, once while non-intoxicated and once while acutely under the influence of their own chosen smoked cannabis on dependence-related measures. Using an unprecedented methodology, a sample of cannabis (as well as saliva) was collected from each user and analyzed for levels of cannabinoids. On the basis of CBD : THC ratios in the cannabis, individuals from the top and bottom tertiles were directly compared on indices of the reinforcing effects of drugs, explicit liking, and implicit attentional bias to drug stimuli. When intoxicated, smokers of high CBD : THC strains showed reduced attentional bias to drug and food stimuli compared with smokers of low CBD : THC. Those smoking higher CBD : THC strains also showed lower self-rated liking of cannabis stimuli on both test days. Our findings suggest that CBD has potential as a treatment for cannabis dependence. The acute modulation of the incentive salience of drug cues by CBD may possibly generalize to a treatment for other addictive disorders.

The reinforcing, self-reported performance and physiological effects of Delta9-tetrahydrocannabinol, triazolam, hydromorphone, and methylphenidate in cannabis users

The use of illicit prescription drugs is common in cannabis users; however, the effects of few psychoactive drugs have been characterized in this population. In this study, Delta-tetrahydrocannabinol (i.e. Delta-THC), triazolam, hydromorphone, and methylphenidate were administered to cannabis users (n=8). Subjects completed the multiple-choice procedure to assess drug reinforcement, as well as self-report questionnaires and performance tasks; physiological assessments were also conducted. Only Delta-THC increased the crossover point on the multiple-choice procedure, but all of the drugs increased ratings on one or more 'positive' drug-effect questionnaire items, as well as items specific for each drug. Triazolam produced the most robust performance impairment, except on a time reproduction task, which was impacted to a greater degree by Delta-THC. Delta-THC elevated heart rate and decreased temperature, triazolam increased heart rate, methylphenidate elevated all cardiovascular indices, and hydromorphone reduced respiration. The effects of the drugs tested in this study were generally consistent with their known pharmacology, although minimal responses to hydromorphone were observed. Future research to directly compare the effects of different psychoactive drugs in cannabis users and nonusers would be useful for identifying potential differences in drug effects as a function of use history.

Biomarkers for the effects of cannabis and THC in healthy volunteers

An increasing number of novel therapeutic agents are targeted at cannabinoid receptors. Drug development programmes of new cannabinoid drugs may be facilitated by the identification of useful biomarkers. This systemic literature review aims to assess the usefulness of direct biomarkers for the effects of cannabis and tetrahydrocannabinol (THC) in healthy volunteers. One hundred and sixty-five useful articles were found that investigated the acute effects of cannabis or THC on the central nervous system (CNS) and heart rate in healthy volunteers. Three hundred and eighteen tests (or test variants) were grouped in test clusters and functional domains, to allow their evaluation as a useful biomarker and to study their dose-response effects. Cannabis/THC affected a wide range of CNS domains. In addition to heart rate, subjective effects were the most reliable biomarkers, showing significant responses to cannabis in almost all studies. Some CNS domains showed indications of depression at lower and stimulation at higher doses. Subjective effects and heart rate are currently the most reliable biomarkers to study the effect of cannabis. Cannabis affects most CNS domains, but too many different CNS tests are used to quantify the drug-response relationships reliably. Test standardization, particularly in motor and memory domains, may reveal additional biomarkers.

Neurocognitive performance during acute THC intoxication in heavy and occasional cannabis users

Performance impairment during Delta(9)-tetrahydrocannabinol (THC) intoxication has been well described in occasional cannabis users. It is less clear whether tolerance develops to the impairing effects of THC in heavy users of cannabis. The aim of the present study was to assess neurocognitive performance during acute THC intoxication in occasional and heavy users. Twenty-four subjects (12 occasional cannabis users and 12 heavy cannabis users) participated in a double-blind, placebo-controlled, two-way mixed model design. Both groups received single doses of THC placebo and 500 microg/kg THC by smoking. Performance tests were conducted at regular intervals between 0 and 8 h after smoking, and included measures of perceptual motor control (critical tracking task), dual task processing (divided attention task), motor inhibition (stop signal task) and cognition (Tower of London). THC significantly impaired performance of occasional cannabis users on critical tracking, divided attention and the stop signal task. THC did not affect the performance of heavy cannabis users except in the stop signal task, i.e. stop reaction time increased, particularly at high THC concentrations. Group comparisons of overall performance in occasional and heavy users did not reveal any persistent performance differences due to residual THC in heavy users. These data indicate that cannabis use history strongly determines the behavioural response to single doses of THC.

Actions of delta-9-tetrahydrocannabinol in cannabis: relation to use, abuse, dependence

Cannabis use disorders have been recently identified as a relevant clinical issue: a subset of cannabis smokers seeks treatment for their cannabis use, yet few succeed in maintaining long-term abstinence. The rewarding and positive reinforcing effects of the primary psychoactive component of smoked cannabis, delta-9-tetrahydrocannabinol (THC) are mediated by the cannabinoid CB1 receptor. The CB1 receptor has also been shown to mediate cannabinoid dependence and expression of withdrawal upon cessation of drug administration, a phenomenon verified across species. This paper will review findings implicating the CB1 receptor in the behavioural effects of exogenous cannabinoids with a focus on cannabinoid dependence and reinforcement, factors that contribute to the maintenance of chronic cannabis smoking despite negative consequences. Opioidergic modulation of these effects is also discussed.

Substitution profile of Delta9-tetrahydrocannabinol, triazolam, hydromorphone, and methylphenidate in humans discriminating Delta9-tetrahydrocannabinol

RATIONALE

Preclinical evidence suggests that non-cannabinoid neurotransmitter systems are involved in the behavioral and physiological effects of cannabinoids, but relatively little research has been conducted in humans.

OBJECTIVES

The aims of this study were to assess whether oral Delta(9)-tetrahydrocannabinol (Delta(9)-THC) would function as a discriminative stimulus in humans and to examine the substitution profile of drugs acting at opioid, GABA, and dopamine systems.

METHODS

Healthy subjects who reported moderate cannabis use were enrolled. Subjects learned to identify when they received oral 25 mg Delta(9)-THC or placebo under double-blind conditions. Once subjects acquired the discrimination (i.e., > or =80% drug-appropriate responding for four consecutive sessions), multiple doses of Delta(9)-THC, the GABA(A) positive modulator triazolam, the micro-opioid agonist hydromorphone and the dopamine reuptake inhibitor methylphenidate were tested to determine if they shared discriminative-stimulus effects with the training dose of Delta(9)-THC.

RESULTS

Eight subjects (N = 8) accurately discriminated Delta(9)-THC and completed the study. The training dose of Delta(9)-THC functioned as a discriminative stimulus and produced prototypical subject-rated drug effects. All of the drugs tested produced significant effects on the self-report questionnaires, but only Delta(9)-THC substituted for the training dose.

CONCLUSION

These results suggest that the discriminative-stimulus effects of Delta(9)-THC in humans are not directly mediated through central neurotransmitter systems acted upon by the drugs tested in this study.

Self-administration of cocaine, cannabis and heroin in the human laboratory: benefits and pitfalls

The objective of this review is to describe self-administration procedures for modeling addiction to cocaine, cannabis and heroin in the human laboratory, the benefits and pitfalls of the approach, and the methodological issues unique to each drug. In addition, the predictive validity of the model for testing treatment medications will be addressed. The results show that all three drugs of abuse are reliably and robustly self-administered by non-treatment-seeking research volunteers. In terms of pharmacotherapies, cocaine use is extraordinarily difficult to disrupt either in the laboratory or in the clinic. A range of medications has been shown to significantly decrease cocaine's subjective effects and craving without decreasing either cocaine self-administration or cocaine abuse by patients. These negative data combined with recent positive findings with modafinil suggest that self-administration procedures are an important intermediary step between pre-clinical and clinical studies. In terms of cannabis, a recent study suggests that medications that improve sleep and mood during cannabis withdrawal decrease the resumption of marijuana self-administration in abstinent volunteers. Clinical data on patients seeking treatment for their marijuana use are needed to validate these laboratory findings. Finally, in contrast to cannabis or cocaine dependence, there are three efficacious Food and Drug Administration-approved medications to treat opioid dependence, all of which decrease both heroin self-administration and subjective effects in the human laboratory. In summary, self-administration procedures provide meaningful behavioral data in a small number of individuals. These studies contribute to our understanding of the variables maintaining cocaine, marijuana and heroin intake, and are important in guiding the development of more effective drug treatment programs.

Use of dronabinol for cannabis dependence: two case reports and review

Marijuana is the most commonly used illicit drug in the United States and throughout the world. Despite this, the number of laboratory studies that have assessed pharmacologic agents to target cannabis withdrawal symptoms or reduce the reinforcing effects of marijuana has been modest. Unlike alcohol, cocaine, opiates, or nicotine, there has been a minimal number of clinical pharmacologic treatment trials that have targeted marijuana use. Based on recent laboratory studies, dronabinol (delta-9-tetrahydrocannabinol) has been shown to reduce cannabis withdrawal symptoms and the subjective effects of marijuana. Given that agonist agents have been found to be effective for opiate and nicotine dependence, the clinical utility of dronabinol for cannabis dependence is a reasonable approach. Two case reports using dronabinol are presented. The potential benefit, as well as questions that arise from the use of this medication in cannabis-abusing populations, is presented. Also, future areas of research that might be explored are discussed.