Tolerance and cross-tolerance to neurocognitive effects of THC and alcohol in heavy cannabis users

Developing a phone-based measure of impairment after acute oral ∆9-tetrahydrocannabinol

BACKGROUND

Acute consumption of cannabis or its primary psychoactive ingredient ∆9-tetrahydrocannabinol has been shown to impair memory, reaction time, time perception, and attention. However, it is difficult to measure these impairments in a brief test that can be used in a non-laboratory setting.

AIMS

We aim to develop and validate a prototype for a mobile phone application to measure ∆9-tetrahydrocannabinol-induced cognitive impairment.

METHODS

We conducted two double-blind, within-subjects studies examining impairments after oral doses of ∆9-tetrahydrocannabinol (0, 7.5, 15 mg) using both standardized computer-based tasks and our novel phone-based tasks. The tasks measured cognitive speed, reaction time, fine motor ability, and working memory and, in the second study, time perception. Study 1 (n=24) provided initial data, and Study 2 (n=24) was designed to refine the measures. In both studies, healthy non-daily cannabis users participated in three four-hour experimental sessions in which they received capsules containing ∆9-tetrahydrocannabinol (7.5, 15 mg) or placebo. Subjective and cardiovascular measures were obtained at regular intervals, and at the time of peak drug effect subjects completed both standardized, computer-based and brief, phone-based tasks.

RESULTS

∆9-Tetrahydrocannabinol-induced impairment was detected on most of the computer tasks, but was not evident on most of the phone tasks.

CONCLUSIONS

The phone tasks were brief, to facilitate use in a non-laboratory setting, but it is likely that this made them less sensitive to the impairing effects of ∆9-tetrahydrocannabinol. These findings confirm that ∆9-tetrahydrocannabinol impairs performance on several tasks at two recreationally relevant doses, but raises question about the feasibility of designing a phone application as a sensitive field sobriety test for cannabis.

A review of the anesthetic implications of marijuana use

Marijuana, derived from plants of the genus Cannabis, is the most commonly used illicit drug in the United States. Marijuana is illegal at the federal level and remains a Drug Enforcement Agency Schedule 1 substance. Nevertheless, most states have passed less stringent legislation related to its use, ranging from decriminalization of possession to allowing medical or even recreational use, and some county and municipal law enforcement agencies have refrained from prosecuting personal possession and/or use even when statute would require such action. Therefore, as use of marijuana becomes more common in the larger population, more patients who are chronic and/or heavy users of marijuana present for surgical procedures, raising the question of best practices to care for these patients in the perioperative period. This review summarizes the known physiologic effects of marijuana in humans, discusses potential implications of marijuana use that the anesthesiologist should consider at each phase of the perioperative period, and outlines recommendations for future study.

Perspectives on cannabis as a substitute for opioid analgesics

With the opioid epidemic reaching new heights in the USA, it has become critical to find suitable alternatives to opioids. Cannabis, an antinociceptive, is a strong contender to help patients reduce their opioid usage. A growing literature has been examining the complex effects cannabis has on pain relief and on opioid usage; whether it is a substitute for opioids or increases their use. This review explores the studies that compare cannabis-opioid interactions and presents some challenges of cannabis research and usage. The practical clinical pharmacology of cannabis as an analgesic, including the route of administration, safety and pharmacokinetics, are discussed to address the concerns, as well as possible solutions, of cannabis as a pain reliever.

Cannabis use during alcohol treatment is associated with alcohol-related problems one-year post-treatment

BACKGROUND

Prior research shows that cannabis use during treatment for Alcohol Use Disorders (AUD) is related to fewer abstinent days from alcohol, although only among those who use cannabis 1-2x/month. Here we extend prior research by assessing the relationship between the frequency of cannabis use during AUD treatment and post-treatment alcohol-related consequences.

METHODS

Data come from the Combined Pharmacotherapies and Behavioral Interventions (COMBINE) Study, a large US randomized control trial of treatments for AUD. The current analyses include 206 cannabis users and 999 cannabis abstainers and compare longitudinal drinking data between those who used cannabis versus those who abstained during COMBINE treatment. The primary exposure was quartiles of cannabis use (Q1: less than 1x/month during treatment, Q2: 1-2x/month, Q3: 4-8x/month, Q4: 12x/month or more), with cannabis abstainers as the reference group. Outcomes were alcohol-related problems at the end of treatment and one-year post-treatment as measured by the Drinker Inventory Consequences.

RESULTS

Compared to cannabis abstinence, the most frequent use during treatment was related to 1.44 times as many physical consequences one-year post-treatment. Cannabis use was not related to physical consequences immediately after treatment, or to intrapersonal, interpersonal, social responsibility or impulse control problems at either post-treatment time point.

CONCLUSIONS

In a sample of individuals in treatment for AUD, using cannabis 12x/month or more during treatment is associated with increased rates of physical consequences attributed to alcohol use. Individuals in treatment for AUD who also use cannabis might benefit from reducing or stopping cannabis use to avoid alcohol-related physical problems.

The dose-dependent psychomotor effects of intravenous delta-9-tetrahydrocannabinol (Δ9-THC) in humans

BACKGROUND

Binding studies have demonstrated that levels of the cannabinoid receptor type-1 are highest in the basal ganglia and cerebellum, two areas critical for motor control. However, no studies have systematically examined the dose-related effects of intravenous delta-9-tetrahydrocannabinol, the primary cannabinoid receptor type-1 partial agonist in cannabis, on broad domains of psychomotor function in humans.

AIMS

Therefore, three domains of psychomotor function were assessed in former cannabis users (cannabis abstinent for a minimum of three months; n=23) in a three test-day, within-subject, double-blind, randomized, cross-over, and counterbalanced study during which they received intravenous delta-9-tetrahydrocannabinol (placebo, 0.015 mg/kg, and 0.03 mg/kg).

METHODS

Gross motor function was assessed via the Cambridge Neuropsychological Test Automated Battery Motor Screening Task, fine motor control via the Lafayette Instrument Grooved Pegboard task, and motor timing via a Paced Finger-Tapping Task. In addition, the Cambridge Neuropsychological Test Automated Battery Rapid Visual Processing Task was utilized to determine whether delta-9-tetrahydrocannabinol-induced motor deficits were confounded by disruptions in sustained attention.

RESULTS/OUTCOMES

Delta-9-tetrahydrocannabinol resulted in robust dose-dependent deficits in fine motor control (Grooved Pegboard Task) and motor timing (Paced Finger-Tapping Task), while gross motor performance (Motor Screening Task) and sustained attention (Rapid Visual Processing Task) were unimpaired. Interestingly, despite the observed dose-dependent increases in motor impairment and blood levels of delta-9-tetrahydrocannabinol, subjects reported similar levels of intoxication in the two drug conditions.

CONCLUSIONS/INTERPRETATION

These data suggest that while several domains of motor function are disrupted by delta-9-tetrahydrocannabinol, subjective feelings of intoxication are dissociable from cannabinoid-induced psychomotor effects. Results are discussed in terms of the potential neural mechanisms of delta-9-tetrahydrocannabinol in motor structures.

Effects of chronic marijuana use on driving performance

OBJECTIVES

The effects of marijuana on driving pose a significant public health concern. More studies on chronic marijuana use in driving are needed. The study objectives were to (1) assess differences in the Standardized Field Sobriety Test (SFST) and driving performance outcomes between chronic medical marijuana users and nonusers and (2) identify a cutoff tetrahydrocannabinol (THC) concentration above which chronic medical marijuana users demonstrate driving impairment.

METHODS

This prospective cross-sectional study assessed 31 chronic marijuana users and 41 nonusers. Rapid Detect Saliva Drug Screen 10-panel was administered to all participants. Participants were given a simple visual reaction time test (SVRT) and SFST consisting of the horizontal gaze nystagmus (HGN), the one leg stand (OLS), and the walk and turn (WAT) tests. The STISIM Drive M100 driving simulator assessed driving performance. Driving parameters included standard deviation of speed (SDS), deviation of mean lane position, off-road accidents, collisions, pedestrians hit, and car-following modulus, delay, and coherence. Cannabinoid blood plasma was obtained from marijuana users.

RESULTS

Marijuana users and nonusers did not differ in age (40.06 ± 13.92 vs. 41.53 ± 15.49, P = .6782). Marijuana users were more likely to fail the SFST (P = .005) and the WAT (P = .012) and HGN (P = .001) components. Marijuana users had slower SVRT (P = .031), less SDS (P = .039), and lower modulus (P = .003). Participants with THC >2 ng/mL (P = .017) and TCH >5 ng/mL (P = .008) had lower SDS. Participants with THC >2 ng/mL (P = .021) and THC >5 ng/mL (P = .044) had decreased modulus.

CONCLUSION

Chronic marijuana users had slower reaction times, deviated less in speed, and had difficulty matching a lead vehicle's speed compared to nonusers. The effects on SDS and modulus were present at cutoffs of 2 and 5 ng/mL.

Alcohol Use and Risk of Related Problems Among Cannabis Users Is Lower Among Those With Medical Cannabis Recommendations, Though Not Due To Health

OBJECTIVE

A small body of work has started developing cannabis use "typologies" for use in treatment and prevention. Two potentially relevant dimensions for classifying cannabis use typologies are medical versus recreational cannabis use and the co-use of cannabis and alcohol. Here we compare alcohol use and related problems between cannabis users with and without medical cannabis recommendations.

METHOD

Data come from a larger general population study in Washington State conducted between January 2014 and October 2016. All participants in the analytic sample (n = 991) reported using both alcohol and cannabis in the past 12 months. The primary exposure was having a medical recommendation for cannabis. Outcomes were past-30-day drinking (drinks/day, frequency of 5+ drinks, and maximum number of drinks in a day) and past-12-month Alcohol Use Disorders Identification Test (AUDIT) scores.

RESULTS

Compared with those without medical cannabis recommendations, cannabis users with medical cannabis recommendations had 0.59 times fewer drinks/day, 0.44 times fewer occasions drinking 5+, and 0.78 times the average maximum number of drinks in one day (all ps < .05). Those with a recommendation also had 0.87 times lower AUDIT total scores (p < .05) and 0.57 times lower AUDIT problem scores (p < .01).

CONCLUSIONS

Cannabis users with medical cannabis recommendations drink less and have fewer alcohol-related problems than those without recommendations, even after adjusting for health status. Future studies should examine nonhealth reasons regarding how medical and nonmedical users use cannabis differently.

Atypical Pharmacodynamic Properties and Metabolic Profile of the Abused Synthetic Cannabinoid AB-PINACA: Potential Contribution to Pronounced Adverse Effects Relative to Δ9-THC

Recreational use of marijuana is associated with few adverse effects, but abuse of synthetic cannabinoids (SCBs) can result in anxiety, psychosis, chest pain, seizures and death. To potentially explain higher toxicity associated with SCB use, we hypothesized that AB-PINACA, a common second generation SCB, exhibits atypical pharmacodynamic properties at CB1 cannabinoid receptors (CB1Rs) and/or a distinct metabolic profile when compared to Δ⁹-tetrahydrocannabinol (Δ⁹-THC), the principal psychoactive cannabinoid present in marijuana. Liquid chromatography tandem mass spectrometry (LC/MS) identified AB-PINACA and monohydroxy metabolite(s) as primary phase I metabolites (4OH-AB-PINACA and/or 5OH-AB-PINACA) in human urine and serum obtained from forensic samples. In vitro experiments demonstrated that when compared to Δ⁹-THC, AB-PINACA exhibits similar affinity for CB1Rs, but greater efficacy for G-protein activation and higher potency for adenylyl cyclase inhibition. Chronic treatment with AB-PINACA also results in greater desensitization of CB1Rs (e.g., tolerance) than Δ⁹-THC. Importantly, monohydroxy metabolites of AB-PINACA retain affinity and full agonist activity at CB1Rs. Incubation of 4OH-AB-PINACA and 5OH-AB-PINACA with human liver microsomes (HLMs) results in limited glucuronide formation when compared to that of JWH-018-M2, a major monohydroxylated metabolite of the first generation SCB JWH-018. Finally, AB-PINACA and 4OH-AB-PINACA are active in vivo, producing CB1R-mediated hypothermia in mice. Taken collectively, the atypical pharmacodynamic properties of AB-PINACA at CB1Rs relative to Δ⁹-THC (e.g., higher potency/efficacy and greater production of desensitization), coupled with an unusual metabolic profile (e.g., production of metabolically stable active phase I metabolites) may contribute to the pronounced adverse effects observed with abuse of this SCB compared to marijuana.

Daily Patterns of Marijuana and Alcohol Co-Use Among Individuals with Alcohol and Cannabis Use Disorders

BACKGROUND

The study aims were to examine daily associations between marijuana and alcohol use and the extent to which the association differs as a function of cannabis use disorder (CUD) and/or alcohol use disorder (AUD) diagnosis.

METHODS

Timeline Followback interview data was collected in a study of veterans (N = 127) recruited from a Veterans Affairs hospital who reported at least 1 day of co-use of marijuana and alcohol in the past 180 days (22,860 observations). Participants reported 40% marijuana use days, 28% drinking days, with 37% meeting DSM-5 criteria for CUD, 40% for AUD, and 15% for both. Use of marijuana on a given day was used to predict a 3-level gender-adjusted drinking variable (heavy: ≥5 (men)/4 (women) drinks; moderate: 1 to 4/3 drinks; or none: 0 drinks). A categorical 4-level variable (no diagnosis, AUD, CUD, or both) was tested as a moderator of the marijuana-alcohol relationship.

RESULTS

Multilevel modeling analyses demonstrated that participants were more likely to drink heavily compared to moderately (OR = 2.34) and moderately compared to not drinking (OR = 1.61) on marijuana use days relative to nonuse days. On marijuana use days, those with AUD and those with AUD + CUD were more likely to drink heavily (OR = 1.91; OR = 2.51, respectively), but those with CUD were less likely to drink heavily (OR = 0.32) compared to moderately, nonsignificant differences between any versus moderate drinking in interaction models.

CONCLUSIONS

Heavy drinking occurs on days when marijuana is also used. This association is particularly evident in individuals diagnosed with both AUD and CUD and AUDs alone but not in those with only CUDs. Findings suggest that alcohol interventions may need to specifically address marijuana use as a risk factor for heavy drinking and AUD.

"Spice" (Synthetic Marijuana) Induced Acute Myocardial Infarction: A Case Series

Marijuana is the most widely abused "recreational" substance in the United States, with highest prevalence in young adults. It is reported to cause ischemic strokes, hepatitis, anxiety, and psychosis. Although it is associated with dose dependent tachycardia and can lead to coronary vasospasm, it has not been directly related to acute myocardial infarction (AMI). Marijuana induced coronary vasospasm can result in endothelial denudation at the site of a vulnerable atherosclerotic plaque in response to hemodynamic stressors, potentially causing an AMI. Spice refers to herbal mixture with composition and effects similar to that of marijuana and therefore is referred to as "synthetic marijuana." Herein, we report 3 cases of spice induced ST-segment elevation myocardial infarction. All patients were relatively young and had few or absolutely no risk factors for cardiovascular disease. All patients underwent emergent coronary angiography, with two needing stent placement and the third requiring only aspiration thrombectomy. Our case series emphasizes the importance of suspecting and investigating synthetic marijuana use in low risk young adults presenting with AMI.

Co-use of Alcohol and Cannabis: A Review

PURPOSE OF REVIEW

The purpose of this review is to provide an overview of the existing literature on the relationship between the co-use of cannabis and alcohol including (1) epidemiology, comorbidity, and associated consequences of cannabis and alcohol use disorders; (2) preclinical and clinical laboratory studies examining behavioral pharmacology of cannabis and alcohol co-use; and (3) clinical outcomes related to co-use.

RECENT FINDINGS

Findings from the literature reviewed suggest that the co-use of alcohol and cannabis is associated with additive performance impairment effects, higher and more frequent consumption levels, increased social and behavioral consequences such as driving while impaired, and greater likelihood of the experiencing comorbid substance use and mental health disorders. Furthermore, co-use may be associated with worse clinical outcomes, yet there are few studies examining the development and evaluation of interventions on reducing the co-use of cannabis and alcohol.

SUMMARY

There is a need for more rigorous and longitudinal research studies on the co-use of cannabis and alcohol to glean a more complete understanding of the relationship between the two substances. Findings can be used to develop and refine intervention strategies to successfully reduce cannabis and alcohol co-use.

Synthetic Pot: Not Your Grandfather's Marijuana

In the early 2000s in Europe and shortly thereafter in the USA, it was reported that 'legal' forms of marijuana were being sold under the name K2 and/or Spice. Active ingredients in K2/Spice products were determined to be synthetic cannabinoids (SCBs), producing psychotropic actions via CB1 cannabinoid receptors, similar to those of Δ9-tetrahydrocannabinol (Δ9-THC), the primary active constituent in marijuana. Often abused by adolescents and military personnel to elude detection in drug tests due to their lack of structural similarity to Δ9-THC, SCBs are falsely marketed as safe marijuana substitutes. Instead, SCBs are a highly structural diverse group of compounds, easily synthesized, which produce very dangerous adverse effects occurring by, as of yet, unknown mechanisms. Therefore, available evidence indicates that K2/Spice products are clearly not safe marijuana alternatives.

Cognitive motor deficits in cannabis users

Cannabis use affects cortico-striatal networks that are essential for producing movement. In this review, we summarize the literature on motor system dysfunction in cannabis users and provide a rationale for why motor learning should be considered an important area in cannabis research. A majority of studies have addressed cognitive impairments in cannabis users and some have focused on driving performance, motor impulsivity, and motor inhibition. Our review of the literature has found that cannabis use is associated with motor performance impairments; however, there is a gap in the literature regarding impairments in motor learning. The involvement of the cortico-striatal network in both cannabis addiction and movement also suggests potential avenues for treatment and rehabilitation via the motor system.

Neurocognitive performance following acute mephedrone administration, with and without alcohol

Recreational use of mephedrone, alone and in combination with alcohol, has increased over the past years. Pharmacological properties of mephedrone share similarities with methylenedioxymethamphetamine (MDMA), but its effect on neurocognitive function has not been well established in humans. The present study assessed the effect of mephedrone alone and after co-administration with alcohol on neurocognitive function. It was hypothesised that mephedrone would improve psychomotor performance but impair memory performance, when administered alone. Neurocognitive performance was expected to be impaired following mephedrone when combined with alcohol. Eleven participants received single doses of 200 mg mephedrone or placebo combined with 0.8 g/kg alcohol or placebo. Neurocognitive performance was assessed at baseline (T₀), at one hour (T₁) and four hours after (T₂) mephedrone administration, by means of the Divided Attention Task (DAT), Critical Tracking Task (CTT), and the Spatial Memory Test (SMT). Mephedrone intoxication impaired short-term spatial memory at T₁ and improved critical tracking performance at T₂ Mephedrone alone did not affect divided attention, but did show an interaction with alcohol on reaction time at T₂ Reaction time decreased when mephedrone was combined with alcohol as compared to alcohol alone. Alcohol intoxication impaired both short- and long-term spatial memory at T₁ and divided attention at T₁ and T₂ Critical tracking performance was not affected by alcohol intoxication. The current findings support the hypothesis that mephedrone improves psychomotor performance, impairs spatial memory and does not affect divided attention performance. Stimulatory effects of mephedrone were not sufficient to compensate for the impairing effects of alcohol on most performance parameters.

Cannabis, alcohol use, psychological distress, and decision-making style

INTRODUCTION

There have been suggestions of hypofrontality in cannabis users. To understand cannabis-related differences in decisional processes, Janis and Mann's conflict model of decision making was applied to recreational cannabis smokers who varied in their alcohol use and level of psychological distress.

METHOD

An online sample of recreational substance users (114 male, 119 female) completed the Melbourne Decision Making Questionnaire, the Alcohol Use Disorders Identification Test (AUDIT), Kessler's Psychological Distress Scale (K10), and the Severity of Dependence Scale (SDS) for cannabis.

RESULTS

Multivariate analysis of variance examined self-reported decision-making styles as a function of gender, recent cannabis use, risky alcohol consumption, and levels of psychological distress. Psychological distress was associated with lower decisional self-esteem and higher levels of procrastination and buck-passing. There were gender differences associated with cannabis use. Female cannabis users reported higher levels of hypervigilance, while male cannabis users reported lower levels of buck-passing.

CONCLUSIONS

Although there was little indication of an avoidant decisional style in cannabis users, the results suggest that cannabis affects decisional processes, contributing to panic in females and impulsivity in males.

Plasma Cannabinoid Pharmacokinetics After Controlled Smoking and Ad libitum Cannabis Smoking in Chronic Frequent Users

More Americans are dependent on cannabis than any other illicit drug. The main analytes for cannabis testing include the primary psychoactive constituent, Δ(9)-tetrahydrocannabinol (THC), equipotent 11-hydroxy-THC (11-OH-THC) and inactive 11-nor-9-carboxy-THC (THCCOOH). Eleven adult chronic frequent cannabis smokers resided on a closed research unit with unlimited access to 5.9% THC cannabis cigarettes from 12:00 to 23:00 during two ad libitum smoking phases, followed by a 5-day abstinence period in seven participants. A single cigarette was smoked under controlled topography on the last day of the smoking and abstinence phases. Plasma cannabinoids were quantified by two-dimensional gas chromatography-mass spectrometry. Median plasma maximum concentrations (Cmax) were 28.3 (THC), 3.9 (11-OH-THC) and 47.0 μg/L (THCCOOH) 0.5 h after controlled single cannabis smoking. Median Cmax 0.2-0.5 h after ad libitum smoking was higher for all analytes: 83.5 (THC), 14.2 (11-OH-THC) and 155 μg/L (THCCOOH). All 11 participants' plasma samples were THC and THCCOOH-positive, 58.3% had THC ≥5 μg/L and 79.2% were 11-OH-THC-positive 8.1-14 h after last cannabis smoking. Cannabinoid detection rates in seven participants 106-112 h (4-5 days) after last smoking were 92.9 (THC), 35.7 (11-OH-THC) and 100% (THCCOOH), with limits of quantification of 0.5 μg/L for THC and THCCOOH, and 1.0 μg/L for 11-OH-THC. These data greatly expand prior research findings on cannabinoid excretion profiles in chronic frequent cannabis smokers during ad libitum smoking. Smoking multiple cannabis cigarettes led to higher Cmax and AUC compared with smoking a single cigarette. The chronic frequent cannabis smokers exhibited extended detection windows for plasma cannabinoids, reflecting a large cannabinoid body burden.

Effect of Blood Collection Time on Measured Δ9-Tetrahydrocannabinol Concentrations: Implications for Driving Interpretation and Drug Policy

BACKGROUND

In driving-under-the-influence cases, blood typically is collected approximately 1.5-4 h after an incident, with unknown last intake time. This complicates blood Δ(9)-tetrahydrocannabinol (THC) interpretation, owing to rapidly decreasing concentrations immediately after inhalation. We evaluated how decreases in blood THC concentration before collection may affect interpretation of toxicological results.

METHODS

Adult cannabis smokers (≥1×/3 months, ≤3 days/week) drank placebo or low-dose alcohol (approximately 0.065% peak breath alcohol concentration) 10 min before inhaling 500 mg placebo, 2.9%, or 6.7% vaporized THC (within-individuals), then took simulated drives 0.5-1.3 h postdose. Blood THC concentrations were determined before and up to 8.3 h postdose (limit of quantification 1 μg/L).

RESULTS

In 18 participants, observed Cmax (at 0.17 h) for active (2.9 or 6.7% THC) cannabis were [median (range)] 38.2 μg/L (11.4-137) without alcohol and 47.9 μg/L (13.0-210) with alcohol. THC Cmax concentration decreased 73.5% (3.3%-89.5%) without alcohol and 75.1% (11.5%-85.4%) with alcohol in the first half-hour after active cannabis and 90.3% (76.1%-100%) and 91.3% (53.8%-97.0%), respectively, by 1.4 h postdose. When residual THC (from previous self-administration) was present, concentrations rapidly decreased to preinhalation baselines and fluctuated around them. During-drive THC concentrations previously associated with impairment (≥8.2 μg/L) decreased to median <5 μg/L by 3.3 h postdose and <2 μg/L by 4.8 h postdose; only 1 participant had THC ≥5 μg/L after 3.3 h.

CONCLUSIONS

Forensic blood THC concentrations may be lower than common per se cutoffs despite greatly exceeding them while driving. Concentrations during driving cannot be back-extrapolated because of unknown time after intake and interindividual variability in rates of decrease.

Cannabis and tolerance: acute drug impairment as a function of cannabis use history

Cannabis use history as predictor of neurocognitive response to cannabis intoxication remains subject to scientific and policy debates. The present study assessed the influence of cannabis on neurocognition in cannabis users whose cannabis use history ranged from infrequent to daily use. Drug users (N = 122) received acute doses of cannabis (300 μg/kg THC), cocaine HCl (300 mg) and placebo. Cocaine served as active control for demonstrating neurocognitive test sensitivity. Executive function, impulse control, attention, psychomotor function and subjective intoxication were significantly worse after cannabis administration relative to placebo. Cocaine improved psychomotor function and attention, impaired impulse control and increased feelings of intoxication. Acute effects of cannabis and cocaine on neurocognitive performance were similar across cannabis users irrespective of their cannabis use history. Absence of tolerance implies that that frequent cannabis use and intoxication can be expected to interfere with neurocognitive performance in many daily environments such as school, work or traffic.

Keep off the grass? Cannabis, cognition and addiction

In an increasing number of states and countries, cannabis now stands poised to join alcohol and tobacco as a legal drug. Quantifying the relative adverse and beneficial effects of cannabis and its constituent cannabinoids should therefore be prioritized. Whereas newspaper headlines have focused on links between cannabis and psychosis, less attention has been paid to the much more common problem of cannabis addiction. Certain cognitive changes have also been attributed to cannabis use, although their causality and longevity are fiercely debated. Identifying why some individuals are more vulnerable than others to the adverse effects of cannabis is now of paramount importance to public health. Here, we review the current state of knowledge about such vulnerability factors, the variations in types of cannabis, and the relationship between these and cognition and addiction.

The sensitivity of laboratory tests assessing driving related skills to dose-related impairment of alcohol: A literature review

Laboratory tests assessing driving related skills can be useful as initial screening tools to assess potential drug induced impairment as part of a standardized behavioural assessment. Unfortunately, consensus about which laboratory tests should be included to reliably assess drug induced impairment has not yet been reached. The aim of the present review was to evaluate the sensitivity of laboratory tests to the dose dependent effects of alcohol, as a benchmark, on performance parameters. In total, 179 experimental studies were included. Results show that a cued go/no-go task and a divided attention test with primary tracking and secondary visual search were consistently sensitive to the impairing effects at medium and high blood alcohol concentrations. Driving performance assessed in a simulator was less sensitive to the effects of alcohol as compared to naturalistic, on-the-road driving. In conclusion, replicating results of several potentially useful tests and their predictive validity of actual driving impairment should deserve further research. In addition, driving simulators should be validated and compared head to head to naturalistic driving in order to increase construct validity.

The Formation of Marijuana Risk Perception in a Population of Substance Abusing Patients

Risk perception has been shown to be protective with regard to marijuana use. Notably, the risk perception of marijuana in individuals with substance abuse problems varies significantly from that of the general public. Understanding how risk perception is formed in substance users could explain these differences and help predict the consequences of policy changes. Using this framework, we explored risk perception and its formation in a sample of substance abusing veterans. Semi-structured interviews were conducted with veterans who were receiving treatment for substance abuse. Interviews were recorded digitally, transcribed verbatim, and analyzed using inductive thematic analysis. A prominent perspective among the 31 participants was that marijuana is significantly different from other drugs because it is safe, not addictive, not associated with physical withdrawal, and has less overt behavioral effects than other substances. Many of these participants drew upon their own innocuous experiences with the drug in developing this perspective, more so than information from any other source. A contrasting narrative emphasized marijuana's capacity to cause negative social consequences, act as a gateway to the use of other, more harmful substances, and cause paranoia or worsen psychosis. In conclusion, individual experience with marijuana featured more prominently in informing risk perception than any other source of information. Our results and previous literature suggest that the significant disconnect between the individual experiences of substance users and the current clinical and legal policy towards marijuana may weaken the legitimacy of public policy or the authority of the medical community.

Repeated administration of phytocannabinoid Δ(9)-THC or synthetic cannabinoids JWH-018 and JWH-073 induces tolerance to hypothermia but not locomotor suppression in mice, and reduces CB1 receptor expression and function in a brain region-specific manner

These studies probed the relationship between intrinsic efficacy and tolerance/cross-tolerance between ∆(9)-THC and synthetic cannabinoid drugs of abuse (SCBs) by examining in vivo effects and cellular changes concomitant with their repeated administration in mice. Dose-effect relationships for hypothermic effects were determined in order to confirm that SCBs JWH-018 and JWH-073 are higher efficacy agonists than ∆(9)-THC in mice. Separate groups of mice were treated with saline, sub-maximal hypothermic doses of JWH-018 or JWH-073 (3.0mg/kg or 10.0mg/kg, respectively) or a maximally hypothermic dose of 30.0mg/kg ∆(9)-THC once per day for 5 consecutive days while core temperature and locomotor activity were monitored via biotelemetry. Repeated administration of all drugs resulted in tolerance to hypothermic effects, but not locomotor effects, and this tolerance was still evident 14 days after the last drug administration. Further studies treated mice with 30.0mg/kg ∆(9)-THC once per day for 4 days, then tested with SCBs on day 5. Mice with a ∆(9)-THC history were cross-tolerant to both SCBs, and this cross-tolerance also persisted 14 days after testing. Select brain regions from chronically treated mice were examined for changes in CB1 receptor expression and function. Expression and function of hypothalamic CB1Rs were reduced in mice receiving chronic drugs, but cortical CB1R expression and function were not altered. Collectively, these data demonstrate that repeated ∆(9)-THC, JWH-018 and JWH-073 can induce long-lasting tolerance to some in vivo effects, which is likely mediated by region-specific downregulation and desensitization of CB1Rs.

Pharmacodynamic interactions of a solid formulation of sodium oxybate and ethanol in healthy volunteers

AIM

The pharmacologic effects of sodium oxybate (SO) have a number of similarities with those of alcohol. This study evaluated the pharmacodynamic interaction of SMO.IR (a solid immediate release formulation of SO) and alcohol (0.7 (males) or 0.57 (females) g kg(-1) alcohol using 40% vodka).

METHODS

In a randomized, double-blind, double-dummy, crossover trial, 24 healthy volunteers received randomly a) 2.25 g SMO.IR and placebo alcohol preparation, b) 2.25 g f SMO.IR and alcohol, c) 2.25 g SMO.IR matching placebo and alcohol and d) 2.25 g of SMO.IR matching placebo and placebo alcohol preparation. Objective and subjective cognitive parameters, adverse events and vital signs were assessed before, 15 and 165 min after treatment administration.

RESULTS

Alcohol produced the expected cognitive impairment and the expected subjective sedation rapidly after intake (from 15 min). The objective effects of SMO.IR were much less pronounced than those of alcohol. The reverse was observed for subjective complaints, which were related to lesser stimulation and greater sedation. Nevertheless, 165 min after administration this sedation feeling was less with SMO.IR than with alcohol. There was a significant interaction between SMO.IR and alcohol at 15 min (i.e. increase in alertness and stimulation and decrease in sedation). In addition, an isolated mild decrease in digit vigilance accuracy occurred at 165 min post-dose after the combination. The co-administration of SMO.IR and alcohol was safe and well-tolerated.

CONCLUSION

SMO.IR and alcohol have distinct adverse effect profiles. The objective effects of SMO.IR are much less marked than those of alcohol. No deleterious interaction was observed.

Cannabis effects on driving lateral control with and without alcohol

BACKGROUND

Effects of cannabis, the most commonly encountered non-alcohol drug in driving under the influence cases, are heavily debated. We aim to determine how blood Δ(9)-tetrahydrocannabinol (THC) concentrations relate to driving impairment, with and without alcohol.

METHODS

Current occasional (≥1×/last 3 months, ≤3days/week) cannabis smokers drank placebo or low-dose alcohol, and inhaled 500mg placebo, low (2.9%)-THC, or high (6.7%)-THC vaporized cannabis over 10min ad libitum in separate sessions (within-subject design, 6 conditions). Participants drove (National Advanced Driving Simulator, University of Iowa) simulated drives (∼0.8h duration). Blood, oral fluid (OF), and breath alcohol samples were collected before (0.17h, 0.42h) and after (1.4h, 2.3h) driving that occurred 0.5-1.3h after inhalation. We evaluated standard deviations of lateral position (lane weave, SDLP) and steering angle, lane departures/min, and maximum lateral acceleration.

RESULTS

In N=18 completers (13 men, ages 21-37years), cannabis and alcohol increased SDLP. Blood THC concentrations of 8.2 and 13.1μg/L during driving increased SDLP similar to 0.05 and 0.08g/210L breath alcohol concentrations, the most common legal alcohol limits. Cannabis-alcohol SDLP effects were additive rather than synergistic, with 5μg/L THC+0.05g/210L alcohol showing similar SDLP to 0.08g/210L alcohol alone. Only alcohol increased lateral acceleration and the less-sensitive lane departures/min parameters. OF effectively documented cannabis exposure, although with greater THC concentration variability than paired blood samples.

CONCLUSIONS

SDLP was a sensitive cannabis-related lateral control impairment measure. During drive blood THC ≥8.2μg/L increased SDLP similar to notably-impairing alcohol concentrations. Despite OF's screening value, OF variability poses challenges in concentration-based effects interpretation.

Controlled vaporized cannabis, with and without alcohol: subjective effects and oral fluid-blood cannabinoid relationships

Vaporized cannabis and concurrent cannabis and alcohol intake are commonplace. We evaluated the subjective effects of cannabis, with and without alcohol, relative to blood and oral fluid (OF, advantageous for cannabis exposure screening) cannabinoid concentrations and OF/blood and OF/plasma vaporized-cannabinoid relationships. Healthy adult occasional-to-moderate cannabis smokers received a vaporized placebo or active cannabis (2.9% and 6.7% Δ(9) -tetrahydrocannabinol, THC) with or without oral low-dose alcohol (~0.065g/210L peak breath alcohol concentration [BrAC]) in a within-subjects design. Blood and OF were collected up to 8.3 h post-dose and subjective effects measured at matched time points with visual-analogue scales and 5-point Likert scales. Linear mixed models evaluated subjective effects by THC concentration, BrAC, and interactions. Effects by time point were evaluated by dose-wise analysis of variance (ANOVA). OF versus blood or plasma cannabinoid ratios and correlations were evaluated in paired-positive specimens. Nineteen participants (13 men) completed the study. Blood THC concentration or BrAC significantly associated with subjective effects including 'high', while OF contamination prevented significant OF concentration associations <1.4 h post-dose. Subjective effects persisted through 3.3-4.3 h, with alcohol potentiating the duration of the cannabis effects. Effect-versus-THC concentration and effect-versus-alcohol concentration hystereses were counterclockwise and clockwise, respectively. OF/blood and OF/plasma THC significantly correlated (all Spearman r≥0.71), but variability was high. Vaporized cannabis subjective effects were similar to those previously reported after smoking, with duration extended by concurrent alcohol. Cannabis intake was identified by OF testing, but OF concentration variability limited interpretation. Blood THC concentrations were more consistent across subjects and more accurate at predicting cannabis' subjective effects. Copyright © 2015 John Wiley & Sons, Ltd.

Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol)

Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

Controlled Cannabis Vaporizer Administration: Blood and Plasma Cannabinoids with and without Alcohol

BACKGROUND

Increased medical and legal cannabis intake is accompanied by greater use of cannabis vaporization and more cases of driving under the influence of cannabis. Although simultaneous Δ(9)-tetrahydrocannabinol (THC) and alcohol use is frequent, potential pharmacokinetic interactions are poorly understood. Here we studied blood and plasma vaporized cannabinoid disposition, with and without simultaneous oral low-dose alcohol.

METHODS

Thirty-two adult cannabis smokers (≥1 time/3 months, ≤3 days/week) drank placebo or low-dose alcohol (target approximately 0.065% peak breath-alcohol concentration) 10 min before inhaling 500 mg placebo, low-dose (2.9%) THC, or high-dose (6.7%) THC vaporized cannabis (6 within-individual alcohol-cannabis combinations). Blood and plasma were obtained before and up to 8.3 h after ingestion.

RESULTS

Nineteen participants completed all sessions. Median (range) maximum blood concentrations (Cmax) for low and high THC doses (no alcohol) were 32.7 (11.4-66.2) and 42.2 (15.2-137) μg/L THC, respectively, and 2.8 (0-9.1) and 5.0 (0-14.2) μg/L 11-OH-THC. With alcohol, low and high dose Cmax values were 35.3 (13.0-71.4) and 67.5 (18.1-210) μg/L THC and 3.7 (1.4-6.0) and 6.0 (0-23.3) μg/L 11-OH-THC, significantly higher than without alcohol. With a THC detection cutoff of ≥1 μg/L, ≥16.7% of participants remained positive 8.3 h postdose, whereas ≤21.1% were positive by 2.3 h with a cutoff of ≥5 μg/L.

CONCLUSIONS

Vaporization is an effective THC delivery route. The significantly higher blood THC and 11-OH-THC Cmax values with alcohol possibly explain increased performance impairment observed from cannabis-alcohol combinations. Chosen driving-related THC cutoffs should be considered carefully to best reflect performance impairment windows. Our results will help facilitate forensic interpretation and inform the debate on drugged driving legislation.

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.

Impulsivity in disorders of food and drug misuse

BACKGROUND

Evidence suggests some overlap between the pathological use of food and drugs, yet how impulsivity compares across these different clinical disorders remains unclear. Substance use disorders are commonly characterized by elevated impulsivity, and impulsivity subtypes may show commonalities and differences in various conditions. We hypothesized that obese subjects with binge-eating disorder (BED) and abstinent alcohol-dependent cohorts would have relatively more impulsive profiles compared to obese subjects without BED. We also predicted decision impulsivity impairment in obesity with and without BED.

METHOD

Thirty obese subjects with BED, 30 without BED and 30 abstinent alcohol-dependent subjects and age- and gender-matched controls were tested on delay discounting (preference for a smaller immediate reward over a larger delayed reward), reflection impulsivity (rapid decision making prior to evidence accumulation) and motor response inhibition (action cancellation of a prepotent response).

RESULTS

All three groups had greater delay discounting relative to healthy volunteers. Both obese subjects without BED and alcohol-dependent subjects had impaired motor response inhibition. Only obese subjects without BED had impaired integration of available information to optimize outcomes over later trials with a cost condition.

CONCLUSIONS

Delay discounting appears to be a common core impairment across disorders of food and drug intake. Unexpectedly, obese subjects without BED showed greater impulsivity than obese subjects with BED. We highlight the dissociability and heterogeneity of impulsivity subtypes and add to the understanding of neurocognitive profiles across disorders involving food and drugs. Our results have therapeutic implications suggesting that disorder-specific patterns of impulsivity could be targeted.

Medical marijuana for cancer

Answer questions and earn CME/CNE Marijuana has been used for centuries, and interest in its medicinal properties has been increasing in recent years. Investigations into these medicinal properties has led to the development of cannabinoid pharmaceuticals such as dronabinol, nabilone, and nabiximols. Dronabinol is best studied in the treatment of nausea secondary to cancer chemotherapy and anorexia associated with weight loss in patients with acquired immune deficiency syndrome, and is approved by the US Food and Drug Administration for those indications. Nabilone has been best studied for the treatment of nausea secondary to cancer chemotherapy. There are also limited studies of these drugs for other conditions. Nabiximols is only available in the United States through clinical trials, but is used in Canada and the United Kingdom for the treatment of spasticity secondary to multiple sclerosis and pain. Studies of marijuana have concentrated on nausea, appetite, and pain. This article will review the literature regarding the medical use of marijuana and these cannabinoid pharmaceuticals (with emphasis on indications relevant to oncology), as well as available information regarding adverse effects of marijuana use.

Alcohol and Relatively Pure Cannabis Use, but Not Schizotypy, are Associated with Cognitive Attenuations

Elevated schizotypy relates to similar cognitive attenuations as seen in psychosis and cannabis/polydrug use. Also, in schizotypal populations cannabis and polydrug (including licit drug) use are enhanced. These cognitive attenuations may therefore either be a behavioral marker of psychotic (-like) symptoms or the consequence of enhanced drug use in schizotypal populations. To elucidate this, we investigated the link between cognitive attenuation and cannabis use in largely pure cannabis users (35) and non-using controls (48), accounting for the potential additional influence of both schizotypy and licit drug use (alcohol, nicotine). Cognitive attenuations commonly seen in psychosis were associated with cannabis and alcohol use, but not schizotypy. Future studies should therefore consider (i) non-excessive licit substance use (e.g., alcohol) in studies investigating the effect of cannabis use on cognition and (ii) both enhanced illicit and licit substance use in studies investigating cognition in schizotypal populations.

Oral fluid cannabinoids in chronic frequent cannabis smokers during ad libitum cannabis smoking

Oral fluid (OF) offers a simple, non-invasive, directly observable sample collection for clinical and forensic drug testing. Given that chronic cannabis smokers often engage in drug administration multiple times daily, evaluating OF cannabinoid pharmacokinetics during ad libitum smoking is important for practical development of analytical methods and informed interpretation of test results. Eleven cannabis smokers resided in a closed research unit for 51 days, and underwent four, 5-day oral delta-9-tetrahydrocannabinol (THC) treatments. Each medication period was separated by 9 days of ad libitum cannabis smoking from 12:00 to 23:00 h daily. Ten OF samples were collected from 9:00-22:00 h on each of the last ad libitum smoking days (Study Days 4, 18, 32, and 46). As the number of cannabis cigarettes smoked increased over the study days, OF THC, cannabinol (CBN), and 11-nor-9-carboxy-THC (THCCOOH) also increased with a significant effect of time since last smoking (Δtime; range, 0.0-17.4 h) and ≥88% detection rates; concentrations on Day 4 were significantly lower than those on Days 32 and 46 but not Day 18. Within 30 min of smoking, median THC, CBN, and THCCOOH concentrations were 689 µg/L, 116 µg/L, and 147 ng/L, respectively, decreasing to 19.4 µg/L, 2.4 µg/L, and 87.6 ng/L after 10 h. Cannabidiol and 11-hydroxy-THC showed overall lower detection rates of 29 and 8.6%, respectively. Cannabinoid disposition in OF was highly influenced by Δtime and composition of smoked cannabis. Furthermore, cannabinoid OF concentrations increased over ad libitum smoking days, in parallel with increased cannabis self-administration, possibly reflecting development of increased cannabis tolerance.

Repeated Δ9-tetrahydrocannabinol exposure in adolescent monkeys: persistent effects selective for spatial working memory

OBJECTIVE

Epidemiological findings suggest that, relative to adults, adolescents are more vulnerable to the adverse persistent effects of cannabis on working memory. However, the potential confounds inherent in human studies preclude direct determination of a cause-and-effect relationship between adolescent cannabis use and heightened susceptibility to persistent working memory impairments. Consequently, the authors examined the effects of repeated exposure to Δ9-tetrahydrocannabinol (THC) on performance of spatial and object working memory tasks in adolescent monkeys.

METHOD

Seven pairs of male adolescent rhesus monkeys, matched for baseline cognitive performance, received vehicle or THC intravenously 5 days/week for 6 months. Performance on spatial and object memory tasks was assessed 23 or 71 hours after drug administration throughout the study. In addition, acute effects on working memory were also assessed at the beginning and end of the 6-month period.

RESULTS

Relative to the vehicle-exposed control animals, those with repeated THC exposure had a blunted trajectory of accuracy improvements on the spatial working memory task in a delay-dependent manner. Accuracy improvements on the object working memory task did not differ between groups. Relative to the acute effects of THC on working memory at the beginning of the study, neither sensitivity nor tolerance was evident after 6 months of THC exposure.

CONCLUSIONS

Because maturation of performance is later for spatial than for object working memory, these findings suggest that persistent effects of THC on cognitive abilities are more evident when exposure coincides with the developmental stage during which the underlying neural circuits are actively maturing.

Sex-dependent long-term effects of adolescent exposure to THC and/or MDMA on neuroinflammation and serotoninergic and cannabinoid systems in rats

BACKGROUND AND PURPOSE

Many young people consume ecstasy as a recreational drug and often in combination with cannabis. In this study, we aimed to mimic human consumption patterns and investigated, in male and female animals, the long-term effects of Δ(9) -tetrahydrocannabinol (THC) and 3,4-methylenedioxymethamphetamine (MDMA) on diverse neuroinflammation and neurotoxic markers.

EXPERIMENTAL APPROACH

Male and female Wistar rats were chronically treated with increasing doses of THC and/or MDMA during adolescence. The effects of THC and/or MDMA on glial reactivity and on serotoninergic and cannabinoid systems were assessed by immunohistochemistry in the hippocampus and parietal cortex.

KEY RESULTS

THC increased the area staining for glial fibrilar acidic protein in both sexes. In males, both drugs, either separately or in combination, increased the proportion of reactive microglia cells [ionized calcium binding adaptor molecule 1 (Iba-1)]. In contrast, in females, each drug, administered alone, decreased of this proportion, whereas the combination of both drugs resulted in a 'normalization' to control values. In males, MDMA reduced the number of SERT positive fibres, THC induced the opposite effect and the group receiving both drugs did not significantly differ from the controls. In females, MDMA reduced the number of SERT positive fibres and the combination of both drugs counteracted this effect. THC also reduced immunostaining for CB1 receptors in females and this effect was aggravated by the combination with MDMA.

CONCLUSIONS AND IMPLICATIONS

Adolescent exposure of rats to THC and/or MDMA induced long-term, sex-dependent neurochemical and glial alterations, and revealed interactions between the two drugs.

LINKED ARTICLES

This article is part of a themed section on Cannabinoids 2013. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2014.171.issue-6.

Can cannabis be considered a substitute medication for alcohol?

AIMS

Substituting cannabis for alcohol may reduce drinking and related problems among alcohol-dependent individuals. Some even recommend prescribing medical cannabis to individuals attempting to reduce drinking. The primary aim of this review is to assess whether cannabis satisfies the seven previously published criteria for substitute medications for alcohol [e.g. 'reduces alcohol-related harms'; 'is safer in overdose than alcohol'; 'should offer significant health economic benefits'; see Chick and Nutt ((2012) Substitution therapy for alcoholism: time for a reappraisal? J Psychopharmacol 26:205-12)].

METHODS

Literature review.

RESULTS

All criteria appear either satisfied or partially satisfied, though studies relying on medical cannabis patients may be limited by selection bias and/or retrospective designs. Individual-level factors, such as severity of alcohol problems, may also moderate substitution.

CONCLUSIONS

There is no clear pattern of outcomes related to cannabis substitution. Most importantly, the recommendation to prescribe alcohol-dependent individuals cannabis to help reduce drinking is premature. Future studies should use longitudinal data to better understand the consequences of cannabis substitution.

Alcohol calibration of tests measuring skills related to car driving

RATIONALE

Medication and illicit drugs can have detrimental side effects which impair driving performance. A drug's impairing potential should be determined by well-validated, reliable, and sensitive tests and ideally be calibrated by benchmark drugs and doses. To date, no consensus has been reached on the issue of which psychometric tests are best suited for initial screening of a drug's driving impairment potential.

OBJECTIVE

The aim of this alcohol calibration study is to determine which performance tests are useful to measure drug-induced impairment. The effects of alcohol are used to compare the psychometric quality between tests and as benchmark to quantify performance changes in each test associated with potentially impairing drug effects.

METHODS

Twenty-four healthy volunteers participated in a double-blind, four-way crossover study. Treatments were placebo and three different doses of alcohol leading to blood alcohol concentrations (BACs) of 0.2, 0.5, and 0.8 g/L.

RESULTS

Main effects of alcohol were found in most tests. Compared with placebo, performance in the Divided Attention Test (DAT) was significantly impaired after all alcohol doses and performance in the Psychomotor Vigilance Test (PVT) and the Balance Test was impaired with a BAC of 0.5 and 0.8 g/L. The largest effect sizes were found on postural balance with eyes open and mean reaction time in the divided attention and the psychomotor vigilance test.

CONCLUSIONS

The preferable tests for initial screening are the DAT and the PVT, as these tests were most sensitive to the impairing effects of alcohol and being considerably valid in assessing potential driving impairment.

An examination of the validity of the standardized field sobriety test in detecting drug impairment using data from the Drug Evaluation and Classification program

OBJECTIVE

The purpose of this study is to assess the validity of the 3 components of the Standardized Field Sobriety Test (SFST), including the Horizontal Gaze Nystagmus (HGN), One Leg Stand (OLS), and Walk and Turn (WAT) tests, in identifying impairment among suspected drug-impaired drivers using data recorded during drug evaluation and classification (DEC) evaluations.

METHODS

Data from 2142 completed DEC evaluations of central nervous system (CNS) stimulants, CNS depressants, narcotic analgesics, cannabis, or no drugs were analyzed using multinomial logistic regression.

RESULTS

All drug categories were significantly associated with impaired performance. On the HGN, users of CNS depressants were significantly more likely to experience lack of smooth pursuit and distinct nystagmus at maximum deviation compared to non-drug users. On the OLS, users of all drug classes were significantly more likely to sway while balancing and use their arms to maintain balance but significantly less likely to hop compared to drug-free cases. Users of CNS depressants, CNS stimulants, and narcotic analgesics were significantly more likely to put their raised foot down during the test. On the WAT, users of CNS depressants, CNS stimulants, and narcotic analgesics were significantly less likely to keep their balance while listening to test instructions compared to those who had not used drugs. Users of CNS depressants were less likely to touch heel-to-toe while walking, whereas individuals who had used narcotic analgesics were less likely to take the correct number of steps.

CONCLUSIONS

These findings provide support for the use of the SFST as a screening tool for law enforcement to identify impairment in persons who have used CNS stimulants, CNS depressants, cannabis, or narcotic analgesics.

Exercise increases plasma THC concentrations in regular cannabis users

BACKGROUND

The major psychoactive ingredient of cannabis, Δ(9)-tetrahydrocannabinol (THC) accumulates in fat tissue from where it slowly diffuses back into blood. THC pre-treated rats can show elevated plasma cannabinoid levels when subjected to conditions that promote fat utilization, such as fasting. Here we examine whether fasting and exercise increase plasma THC concentrations in regular cannabis users.

METHODS

Fourteen regular cannabis users completed 35 min of exercise on a stationary bicycle in either a fed or overnight fasted state. Plasma cannabinoid levels were assessed prior to exercise, immediately post-exercise and 2h post-exercise. Plasma samples were also analyzed for indices of lipolysis (free fatty acids (FFA) and glycerol).

RESULTS

Exercise induced a small, statistically significant increase in plasma THC levels accompanied by increased plasma FFA and glycerol levels. Exercise-induced increases in plasma THC concentrations were positively correlated with body mass index. Fasting induced a significant increase in plasma FFA levels, and a lowering of blood glucose, but did not significantly alter plasma cannabinoid levels.

CONCLUSIONS

Here we demonstrate that exercise enhances plasma THC levels in regular cannabis users. The lack of a fasting effect may reflect the modest duration of fasting used which was associated with only a modest increase in fat utilization relative to exercise. Overall, these results suggest that exercise may elevate blood THC levels by releasing dormant THC from fat stores. These data suggest the interpretation of blood THC levels in roadside and workplace tests might be complicated by recent exercise.

Single doses of THC and cocaine decrease proficiency of impulse control in heavy cannabis users

BACKGROUND AND PURPOSE

Cannabis is the most popular drug used in the European Union, closely followed by cocaine. Whereas cannabis impairs neurocognitive function in occasional cannabis users, such impairments appear less prominent in heavy users, possibly as a result of tolerance. The present study was designed to assess whether the impairing effects of Δ(9) -tetrahydrocannabinol (THC) in heavy cannabis users would present in a wide range of neuropsychological functions or selectively affect specific performance domains. We also assessed the acute effects of cocaine on neurocognitive functions of heavy cannabis users.

EXPERIMENTAL APPROACH

Heavy cannabis users, who had a history of cocaine use (n = 61), participated in a double-blind, placebo-controlled, three-way crossover study. Subjects received single doses of cocaine HCl (300 mg), cannabis (THC μg·kg(-1) ) and placebo, and completed a number of tests measuring impulse control and psychomotor function.

KEY RESULTS

Single doses of cannabis impaired psychomotor function and increased response errors during impulsivity tasks. Single doses of cocaine improved psychomotor function and decreased response time in impulsivity tasks, but increased errors.

CONCLUSIONS AND IMPLICATIONS

Heavy cannabis users display impairments in a broad range of neuropsychological domains during THC intoxication. Impairments observed in psychomotor tasks, but not in impulsivity tasks, appeared smaller in magnitude as compared with those previously reported in occasional cannabis users. Heavy cannabis users were sensitive to the stimulating and inhibitory effects of cocaine on psychomotor function and impulsivity respectively. The reduction in proficiency in impulse control may put drug users at increased risk of repeated drug use and addiction.

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.

Impact of prolonged cannabinoid excretion in chronic daily cannabis smokers' blood on per se drugged driving laws

BACKGROUND

Cannabis is the illicit drug most frequently reported with impaired driving and motor vehicle accidents. Some "per se" laws make it illegal to drive with any amount of drug in the body, while others establish blood, saliva, or urine concentrations above which it is illegal to drive. The persistence of Δ(9)-tetrahydrocannabinol (THC) in chronic daily cannabis smokers' blood is unknown.

METHODS

Thirty male chronic daily cannabis smokers resided on a secure research unit for up to 33 days, with daily blood collection. Samples were processed in an ice bath during sample preparation to minimize cannabinoid adsorption onto precipitant material. We quantified THC by 2-dimensional GC-MS.

RESULTS

Of the 30 participants, 27 were THC-positive on admission, with a median (range) concentration of 1.4 μg/L (0.3-6.3). THC decreased gradually; only 1 of 11 participants was negative at 26 days, 2 of 5 remained THC-positive (0.3 μg/L) for 30 days, and 5.0% of participants had THC ≥ 1.0 μg/L for 12 days. Median 11-hydroxy-THC concentrations were 1.1 μg/L on admission, with no results ≥ 1.0 μg/L 24 h later. 11-Nor-9-carboxy-THC (THCCOOH) detection rates were 96.7% on admission, decreasing slowly to 95.7% and 85.7% on days 8 and 22, respectively; 4 of 5 participants remained THCCOOH positive (0.6-2.7 μg/L) after 30 days, and 1 remained positive on discharge at 33 days.

CONCLUSIONS

Cannabinoids can be detected in blood of chronic daily cannabis smokers during a month of sustained abstinence. This is consistent with the time course of persisting neurocognitive impairment reported in recent studies.

Cannabis effects on driving skills

BACKGROUND

Cannabis is the most prevalent illicit drug identified in impaired drivers. The effects of cannabis on driving continue to be debated, making prosecution and legislation difficult. Historically, delays in sample collection, evaluating the inactive Δ(9)-tetrahydrocannabinol (THC) metabolite 11-nor-9-carboxy-THC, and polydrug use have complicated epidemiologic evaluations of driver impairment after cannabis use.

CONTENT

We review and evaluate the current literature on cannabis' effects on driving, highlighting the epidemiologic and experimental data. Epidemiologic data show that the risk of involvement in a motor vehicle accident (MVA) increases approximately 2-fold after cannabis smoking. The adjusted risk of driver culpability also increases substantially, particularly with increased blood THC concentrations. Studies that have used urine as the biological matrix have not shown an association between cannabis and crash risk. Experimental data show that drivers attempt to compensate by driving more slowly after smoking cannabis, but control deteriorates with increasing task complexity. Cannabis smoking increases lane weaving and impaired cognitive function. Critical-tracking tests, reaction times, divided-attention tasks, and lane-position variability all show cannabis-induced impairment. Despite purported tolerance in frequent smokers, complex tasks still show impairment. Combining cannabis with alcohol enhances impairment, especially lane weaving.

SUMMARY

Differences in study designs frequently account for inconsistencies in results between studies. Participant-selection bias and confounding factors attenuate ostensible cannabis effects, but the association with MVA often retains significance. Evidence suggests recent smoking and/or blood THC concentrations 2-5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Future cannabis-and-driving research should emphasize challenging tasks, such as divided attention, and include occasional and chronic daily cannabis smokers.

Influence of ethanol on the pharmacokinetic properties of Δ9-tetrahydrocannabinol in oral fluid

Oral fluid (OF) tests aid in identifying drivers under the influence of drugs. In this study, 17 heavy cannabis users consumed alcohol to achieve steady blood alcohol concentrations of 0 to 0.7 g/L and smoked cannabis 3 h afterward. OF samples were obtained before and up to 4 h after smoking and on-site tests were performed (Dräger DrugTest 5000 and Securetec DrugWipe 5+). Maximum concentrations of tetrahydrocannabinol (THC) immediately after smoking (up to 44,412 ng/g) were below 4,300 (median 377) ng/g 1 h after smoking and less than 312 (median 88) ng/g 3 h later with 5 of 49 samples negative, suggesting that recent cannabis use might occasionally not be detectable. An influence of alcohol was not observed. Drinking 300 mL variably influenced THC concentrations (median only -29.6%), which suggests that drinking does not markedly affect on-site test performance. Many (92%) Dräger tests performed 4 h after smoking were still positive, indicating sufficient sensitivity for recent cannabis use. Differences in the results of a roadside study with DrugTest 5000 (sensitivity 84.8%, specificity 96.0%, accuracy 84.3%) could be explained by a higher number of true negatives, differences between OF and serum and differences between occasional and chronic users.

Low-dose vaporized cannabis significantly improves neuropathic pain

We conducted a double-blind, placebo-controlled, crossover study evaluating the analgesic efficacy of vaporized cannabis in subjects, the majority of whom were experiencing neuropathic pain despite traditional treatment. Thirty-nine patients with central and peripheral neuropathic pain underwent a standardized procedure for inhaling medium-dose (3.53%), low-dose (1.29%), or placebo cannabis with the primary outcome being visual analog scale pain intensity. Psychoactive side effects and neuropsychological performance were also evaluated. Mixed-effects regression models demonstrated an analgesic response to vaporized cannabis. There was no significant difference between the 2 active dose groups' results (P > .7). The number needed to treat (NNT) to achieve 30% pain reduction was 3.2 for placebo versus low-dose, 2.9 for placebo versus medium-dose, and 25 for medium- versus low-dose. As these NNTs are comparable to those of traditional neuropathic pain medications, cannabis has analgesic efficacy with the low dose being as effective a pain reliever as the medium dose. Psychoactive effects were minimal and well tolerated, and neuropsychological effects were of limited duration and readily reversible within 1 to 2 hours. Vaporized cannabis, even at low doses, may present an effective option for patients with treatment-resistant neuropathic pain.

PERSPECTIVE

The analgesia obtained from a low dose of delta-9-tetrahydrocannabinol (1.29%) in patients, most of whom were experiencing neuropathic pain despite conventional treatments, is a clinically significant outcome. In general, the effect sizes on cognitive testing were consistent with this minimal dose. As a result, one might not anticipate a significant impact on daily functioning.

The effect of cannabis use on memory function: an update

Investigating the effects of cannabis use on memory function appears challenging. While early observational investigations aimed to elucidate the longer-term effects of cannabis use on memory function in humans, findings remained equivocal and pointed to a pattern of interacting factors impacting on the relationship between cannabis use and memory function, rather than a simple direct effect of cannabis. Only recently, a clearer picture of the chronic and acute effects of cannabis use on memory function has emerged once studies have controlled for potential confounding factors and started to investigate the acute effects of delta-9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD), the main ingredients in the extract of the cannabis plant in pharmacological challenge experiments. Relatively consistent findings have been reported regarding the acute impairments induced by a single dose of Δ9-THC on verbal and working memory. It is unclear whether they may persist beyond the intoxication state. In the long-term, these impairments seem particularly likely to manifest and may also persist following abstinence if regular and heavy use of cannabis strains high in Δ9-THC is started at an early age. Although still at an early stage, studies that employed advanced neuroimaging techniques have started to model the neural underpinnings of the effects of cannabis use and implicate a network of functional and morphological alterations that may moderate the effects of cannabis on memory function. Future experimental and epidemiological studies that take into consideration individual differences, particularly previous cannabis history and demographic characteristics, but also the precise mixture of the ingredients of the consumed cannabis are necessary to clarify the magnitude and the mechanisms by which cannabis-induced memory impairments occur and to elucidate underlying neurobiological mechanisms.