Impairment due to cannabis and ethanol: clinical signs and additive effects

Cannabis Recreational Legalization and Prevalence of Simultaneous Cannabis and Alcohol Use in the United States

BACKGROUND

Simultaneous cannabis/alcohol use, using both substances within a short time interval so that their effects overlap, has a greater risk of potential negative consequences than single-substance use and is more common in younger age. Relationships between recreational cannabis laws (RCLs) and changes in simultaneous cannabis/alcohol use prevalence remain untested.

OBJECTIVE

To examine trends in simultaneous cannabis/alcohol use from 2008 to 2019, and investigate associations between implementation of RCLs (i.e., presence of active legal dispensaries or legal home cultivation) and simultaneous cannabis/alcohol use in the United States (U.S.).

DESIGN

Repeated cross-sectional samples from the 2008-2019 U.S. National Survey on Drug Use and Health (NSDUH).

PARTICIPANTS

Respondents (51% female) aged 12 and older.

INTERVENTIONS

Changes in simultaneous cannabis/alcohol use before and after RCL implementation (controlling for medical cannabis law implementation) were compared in different age groups (12-20, 21-30, 31-40, 41-50, 51+), using adjusted multi-level logistic regression with state random intercepts and an RCL/age group interaction.

MEASUREMENTS

Self-reported simultaneous cannabis/alcohol use.

RESULTS

From 2008 to 2019, the overall prevalence of simultaneous cannabis/alcohol use declined among those aged 12-20 but increased in adults aged 21+. Model-based simultaneous cannabis/alcohol use prevalence increased after RCL implementation among respondents aged 21-30 years (+1.2%; aOR= 1.15 [95%CI = 1.04-1.27]), 31-40 years (+1.0; 1.15 [1.04-1.27]), and 41-50 years (+1.75; 1.63 [1.34-1.98]), but not in individuals aged <21 or 51+ years.

CONCLUSIONS

Implementation of recreational cannabis policies resulted in increased simultaneous use of cannabis and alcohol, supporting the complementarity hypothesis, but only among adults aged 21+. Efforts to minimize harms related to simultaneous cannabis/alcohol use are critical, especially in states with RCLs. Future studies should investigate cultural norms, perceived harm, and motives related to simultaneous use.

Study design to evaluate a web-intervention to prevent alcohol and cannabis-impaired driving and use among adolescents in driver education

BACKGROUND

Alcohol and cannabis are the most commonly used substances among adolescents in the U.S. The consequences related to using both substances together are significantly higher relative to use of either substance alone. Teens' propensity to engage in risky driving behaviors (e.g., speeding, rapid lane changes, and texting) and their relative inexperience with the timing and duration of cannabis' effects puts them at heightened risk for experiencing harms related to driving under the influence. Use of alcohol and cannabis peak at age 16, the legal age teens may apply for a provisional driver's license in some states. Targeting novice teen drivers prior to licensure is thus an ideal time for prevention efforts focused on reducing alcohol and/or cannabis initiation, use, and impaired driving.

METHODS

The current study proposes to evaluate the efficacy of webCHAT among 15.5 to 17-year-old adolescents (n = 150) recruited at driver education programs. WebCHAT is a single session online intervention that aims to prevent alcohol and cannabis use and risky driving behaviors. We will recruit adolescents enrolled in driver education programs, and stratify based on whether they used cannabis and/or alcohol in the past 3 months (60% screening negative and 40% screening positive). All participants will receive usual driver education and half will also receive webCHAT. We will test whether webCHAT in addition to usual driver education reduces alcohol and/or cannabis initiation or use and reduces risky driving attitudes and behaviors (intent to drive after drinking/using, riding as a passenger with someone who drank/used) compared to teens in usual driver education over a 6-month period. We will also explore whether variables such as beliefs and perceived norms serve as explanatory mechanisms for our outcomes.

DISCUSSION

The study has the potential to promote public welfare by decreasing adolescent initiation and use of cannabis and alcohol and reducing risky driving behaviors that can have substantial monetary, personal, and social costs. The study recruits adolescents who are at risk for substance use as well as those who are not and it is delivered remotely during a teachable moment when adolescents receive driver education. Trial registration This study was registered with ClinicalTrials.gov on July 13, 2021 (NCT04959461). https://clinicaltrials.gov/ct2/show/NCT04959461.

Nystagmus among suspected amphetamine impaired drivers

Clinical signs of drug use can be helpful to identify which drug has been consumed. Amphetamine intake has traditionally not been considered to cause nystagmus. The aim of this study was to explore whether there is a relationship between amphetamine use and nystagmus in a population of apprehended drivers in a naturalistic setting. We evaluated drivers suspected of drug-impaired driving where blood samples were collected and a clinical test of impairment (CTI) was performed. Evaluation of nystagmus is one of the CTI subtests. The samples were analysed for alcohol and psychoactive drugs. Cases with a nystagmus test were recorded and amphetamine-only cases were compared with alcohol-only cases and with cases where alcohol or drugs were not detected, respectively. Samples from 507 amphetamine-only cases were compared to 485 alcohol-only cases and 205 drug-negative cases. The median blood amphetamine concentration was 0.37 mg/L and the median alcohol concentration was 1.57 g/kg. The proportion of cases with nystagmus was similar in amphetamine-only cases (21%) and drug-negative controls (25%), p = 0.273, but higher in alcohol-only cases (53%), p < 0.001. No association was found between the blood amphetamine concentration and degree of nystagmus (Spearman's ρ = 0.008, p = 0.860), whereas an association between blood alcohol concentration and degree of nystagmus was demonstrated (ρ = 0.249, p < 0.001). In conclusion, our study did not find that apprehended drivers using amphetamine had more frequently nystagmus than a control group that tested negative for alcohol and drugs, even at high amphetamine concentrations in blood. Hence, nystagmus should not be considered a tool for identifying amphetamine-induced impairment in drivers.

Development of the Alcohol and Cannabis Simultaneous Use Scale (ACSUS) in College Students

Background

Despite the prevalence and negative outcomes associated with simultaneous alcohol and cannabis use (i.e., marijuana [SAM] use; i.e., so that the effects of both alcohol and cannabis overlap) among college students, there is no comprehensive measure of SAM use, with past research relying on single items. The present studies aimed to develop the Alcohol and Cannabis Simultaneous Use Scale (ACSUS), a comprehensive self-report measure of SAM use frequency, quantity, and problems in college students.

Methods

College students at two Midwestern universities who used alcohol and cannabis (Study 1: N=534; Mean age=19; 71% female; 88% White; Study 2: N=258; Mean age=21; 81% female; 85% White) completed the newly developed ACSUS.

Results

Exploratory factor analysis (Study 1) revealed the ACSUS fit best with 9-items representing two factors: Factor 1 measures frequency and quantity of SAM use, and Factor 2 measures associated problems with SAM use. Confirmatory factor analysis (Study 2) supported the two-factor structure of the ACSUS which was positively associated with measures of alcohol use, cannabis use, simultaneous use motives, and impulsivity.

Conclusions

These data provide initial support for the ACSUS, developed to investigate the frequency, quantity, and associated problems with SAM use in college students.

The Redesign of a Checklist for Evaluating Driver Impairment: A Human Factors and Ergonomics Approach

The Cantonal Police of Zurich, Switzerland, use a checklist to identify impaired drivers when conducting traffic stops. This checklist was developed by subject-matter experts and has been in use for eight years. The goal of this study was to redesign the checklist while considering human factors and ergonomics principles in combination with findings from a retrospective analysis of a set of 593 completed checklists. The checklist was amended in accordance with the results of the retrospective analysis by adding missing items and discarding superfluous ones. In addition, a hierarchical cluster analysis of the retrospective data suggested an improved spatial organization of checklist elements and the grouping of similar items of the checklist. Furthermore, aspects related to Fitts’s law, visual complexity, and an optimized direction of processing the checklist underpinned the design process. The results of an evaluation of the redesigned checklist by 11 laypeople and 13 police officers indicated an improved usability of the redesigned checklist over the original.

Cannabis use and subjective response to alcohol in the human laboratory

BACKGROUND

Cannabis is often used in combination with alcohol; yet, whether cannabis use impacts risk factors for alcohol use disorder (AUD) remains unknown. Subjective response (SR) to alcohol represents a biobehavioral risk factor for subsequent heavy drinking and for developing AUD. Given the high prevalence of alcohol and cannabis co-use, it is plausible to hypothesize that cannabis users differ in SR to alcohol compared to non-cannabis users. The purpose of this study is to examine the influence of past-month cannabis use on subjective response to alcohol in the human laboratory.

METHODS

This study culled data from multiple alcohol administration trials to test whether cannabis users, compared to non-cannabis users, differed in subjective response to alcohol, comprised of four domains: stimulation, sedation, negative affect, and craving. Non-treatment-seeking heavy drinkers (N = 168) completed a battery of self-report scales of mood and alcohol/cigarette/cannabis use and problems. All participants completed an intravenous alcohol administration session wherein SR domains were measured at the following breath alcohol concentrations (BrAC): baseline (i.e., 0), 20, 40, and 60 mg%.

RESULTS

Multilevel statistical analyses revealed that cannabis users had a greater reduction in negative affect during alcohol administration, compared to non-cannabis users. No significant differences were found for the other SR domains.

CONCLUSIONS

Using a large sample and advanced data analytic methods, this study extends the literature by suggesting that cannabis users are more sensitive to alcohol-induced reductions in negative affect compared to non-cannabis users. This work extends research on how cannabis use may influence risk factors for AUD, such as subjective response to alcohol.

The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic review and meta-analysis

BACKGROUND AND AIMS

Cannabis and alcohol are frequently detected in fatal and injury motor vehicle crashes. While epidemiological meta-analyses of cannabis and alcohol have found associations with an increase in crash risk, convergent evidence from driving performance measures is insufficiently quantitatively characterized. Our objectives were to quantify the magnitude of the effect of cannabis and alcohol-alone and in combination-on driving performance and behaviour.

METHODS

Systematic review and meta-analysis. We systematically searched Academic Search Complete, CINAHL, Embase, Scopus, Google Scholar, MEDLINE, PsycINFO, SPORTDiscus and TRID. Of the 616 studies that underwent full-text review, this meta-analysis represents 57 studies and 1725 participants. We extracted data for hazard response time, lateral position variability, lane deviations or excursions, time out of lane, driving speed, driving speed variability, speed violations, time speeding, headway, headway variability and crashes from experimental driving studies (i.e. driving simulator, closed-course, on-road) involving cannabis and/or alcohol administration. We reported meta-analyses of effect sizes using Hedges' g and r.

RESULTS

Cannabis alone was associated with impaired lateral control [e.g. g = 0.331, 95% confidence interval (CI) = 0.212-0.451 for lateral position variability; g = 0.198, 95% CI = 0.001-0.395 for lane excursions) and decreased driving speed (g = -0.176, 95% CI = -0.298 to -0.053]. The combination of cannabis and alcohol was associated with greater driving performance decrements than either drug in isolation [e.g. g = 0.480, 95% CI = 0.096-0.865 for lateral position variability (combination versus alcohol); g = 0.525, 95% CI = 0.049-1.002 for time out of lane (versus alcohol); g = 0.336, 95% CI = 0.036-0.636 for lateral position variability (combination versus cannabis; g = 0.475, 95% CI = 0.002-0.949 for time out of lane (combination versus cannabis)]. Subgroup analyses indicated that the effects of cannabis on driving performance measures were similar to low blood alcohol concentrations. A scarcity of data and study heterogeneity limited the interpretation of some measures.

CONCLUSIONS

This meta-analysis indicates that cannabis, like alcohol, impairs driving, and the combination of the two drugs is more detrimental to driving performance than either in isolation.

Combined effect of alcohol and cannabis on simulated driving

RATIONALE

With alcohol and cannabis remaining the most commonly detected drugs in seriously and fatally injured drivers, there is a need to understand their combined effects on driving.

OBJECTIVES

The present study examined the effects of combinations of smoked cannabis (12.5% THC) and alcohol (target BrAC 0.08%) on simulated driving performance, subjective drug effects, cardiovascular measures, and self-reported perception of driving ability.

METHODS

In this within-subjects, double-blind, double-dummy, placebo-controlled, randomized clinical trial, cannabis users (1-7 days/week) aged 19-29 years attended four drug administration sessions in which simulated driving, subjective effects, cardiovascular measures, and whole blood THC and metabolite concentrations were assessed following placebo alcohol and placebo cannabis (<0.1% THC), alcohol and placebo cannabis, placebo alcohol and active cannabis, and alcohol and active cannabis.

RESULTS

Standard deviation of lateral position in the combined condition was significantly different from the placebo condition (p < 0.001). Standard deviation of lateral position was also significantly different from alcohol and cannabis alone conditions in the single task overall drive (p = 0.029 and p = 0.032, respectively), from the alcohol alone condition in the dual task overall drive (p = 0.022) and the cannabis alone condition in the dual task straightaway drive (p = 0.002). Compared to the placebo condition, the combined and alcohol conditions significantly increased reaction time. Subjective effects in the combined condition were significantly greater than with either of the drugs alone at some time points, particularly later in the session. A driving ability questionnaire showed that participants seemed unaware of their level of impairment.

CONCLUSION

Combinations of alcohol and cannabis increased weaving and reaction time, and tended to produce greater subjective effects compared to placebo and the single drug conditions suggesting a potential additive effect. The fact that participants were unaware of this increased effect has important implications for driving safety.

Patterns of Cannabis and Alcohol Co-Use: Substitution Versus Complementary Effects

PURPOSE

The purpose of this review is to discuss the literature regarding the concurrent use (co-use) of alcohol and cannabis and competing hypotheses as to whether cannabis acts as a substitute for (i.e., replacing the effects of alcohol, resulting in decreased use) or a complement to (i.e., used to enhance the effects of alcohol, resulting in increased use) alcohol. The impact of cannabis use on alcohol-related outcomes has received increased attention in the wake of ongoing legalization of cannabis for both medical and recreational purposes. Evidence for both hypotheses exists in the literature across a broad range of data collection methods and samples and is carefully reviewed here. In addition, various mechanisms by which cannabis may act as an alcohol substitute or complement are explored in depth with the goal of better understanding equivocal findings.

SEARCH METHODS

This review includes articles that were identified from a search for studies on alcohol and cannabis co-use, with a specific focus on studies exploring complementary versus substitution aspects of co-use. Search terms were included in Google Scholar, PsycINFO, MEDLINE, and Web of Science. Eligible studies were those that measured alcohol and cannabis co-use in human samples in laboratory, survey, or ecological momentary assessment studies, or that directly referenced substitution or complementary patterns of use.

SEARCH RESULTS

Search results returned 650 articles, with 95 meeting inclusion criteria.

DISCUSSION AND CONCLUSIONS

Results of this review reveal compelling evidence for both substitution and complementary effects, suggesting nuanced yet significant distinctions across different populations examined in these studies. Several mechanisms for the impact of cannabis use on alcohol-related outcomes are identified, including patterns and context of co-use, timing and order of use, cannabinoid formulation, pharmacokinetic interactions, and user characteristics (including diagnostic status), all of which may influence substitution versus complementary effects. This review will inform future research studies examining this topic in both clinical and community samples and aid in the development of treatment and prevention efforts targeting those populations most vulnerable to negative consequences of co-use. Finally, this review highlights the need for additional research in more diverse samples and the use of mixed-methods designs to examine both pharmacological and contextual influences on co-use.

Prevalence and associated risk factors of cannabinoid abuse among Egyptian university students: a cross-sectional study

Global surveys have highlighted rise in consumption of cannabinoids among residents of both developed and developing countries. Cannabinoids cause severe damage to the cardiovascular, nervous, respiratory, and renal systems, and have been linked with several deaths. Despite these adverse health effects, the use of cannabinoids has rapidly increased. This work seeks to estimate the prevalence of cannabinoid abuse among Egyptian university students and explore the associated risk factors. A cross-sectional study was carried out over 3 months (1st of July-1st of October 2020) and included 2380 students. Participants were subjected to a pre-designed self-administered questionnaire that included demographic data, Addiction Severity Index, and Depression Anxiety Stress Scale. Among the participating students, 4.9% of them reported cannabinoid abuse and 41% reported smoking cigarettes. The most used substances were hashish (96.5%), Strox (41.3%), Bhang (34.4%), voodoo (34.4%), and Tramadol (31.1%). Gender and social status were also significantly related to rates of substances abuse; most illicit drug users were males (93.1%), and the majority was of low (41.3%) or moderate (50.8%) socioeconomic status. The most significant risk factors associated with substance use were positive history of family conflict (OR=6.48; CI95%: 5.08-8.64, p<0.001), encouragement by peers (OR=2.95; CI95%: 1.73-5.05, p<0.001), male gender (OR=5.46; CI95%: 2.40-12.44, p=0.001), positive history of child abuse (OR=2.85; CI95%: 1.96-3.04, p=0.001), having a stay-at-home mother (OR= 1.56, CI95%: 1.19-2.04, p=0.001), living in an urban area (OR=2.22; CI95%: 1.53-5.0, p=0.002), and positive family history of substance use (OR=1.98; CI95%: 1.48-2.08, p=0.045). This study emphasizes the possible significant rise in substance use among university students. Awareness campaigns should target both students and student families.

Mechanisms of cannabis impairment: Implications for modeling driving performance

Past research on cannabis has been limited in scope to THC potencies lower than legally available and efforts to integrate the effects into models of driving performance have not been attempted to date. The purpose of this systematic review is to understand the implications for modeling driving performance and describe future research needs. The risk of motor vehicle crashes increases 2-fold after smoking marijuana. Driving during acute cannabis intoxication impairs concentration, reaction time, along with a variety of other necessary driving-related skills. Changes to legislation in North America and abroad have led to an increase in cannabis' popularity. This has given rise to more potent strains, with higher THC concentrations than ever before. There is also rising usage of novel ingestion methods other than smoking, such as oral cannabis products (e.g., brownies, infused drinks, candies), vaping, and topicals. The PRISMA guidelines were followed to perform a systematic search of the PubMed database for peer-reviewed literature. Search terms were combined with keywords for driving performance: driving, performance, impairment. Grey literature was also reviewed, including congressional reports, committee reports, and roadside surveys. There is a large discrepancy between the types of cannabis products sold and what is researched. Almost all studies that used inhalation as the mode of ingestion with cannabis that is around 6% THC. This pales in comparison to the more potent strains being sold today which can exceed 20%. Which is to say nothing of extracts, which can contain 60% or more THC. Experimental protocol is another gap in research that needs to be filled. Methodologies that involve naturalistic (real world) driving environments, smoked rather than vaporized cannabis, and non-lab certified products introduce uncontrollable variables. When considering the available literature and the implications of modeling the impacts of cannabis on driving performance, two critical areas emerge that require additional research: The first is the role of cannabis potency. Second is the route of administration. Does the lower peak THC level result in smaller impacts on performance? How long does potential impairment last along the longer time-course associated with different pharmacokinetic profiles. It is critical for modeling efforts to understand the answers to these questions, accurately model the effects on driver performance, and by extension understand the risk to the public.

Alcohol, marijuana, and nicotine use as predictors of impaired driving and riding with an impaired driver among college students who engage in polysubstance use

OBJECTIVE

While alcohol, marijuana, and nicotine are the most commonly used substances, there is limited research on the between- and within-person associations of their use and driving under the influence (DUI) and riding with an impaired driver (RWID). The current study utilized a burst design to assess how use and co-use of these substances is associated with DUI and RWID.

METHODS

College student drinkers with past-year marijuana and/or nicotine use (N = 367) were assessed on two consecutive weekends for three semesters. Logistic regression compared students who only reported drinking to student drinkers who used marijuana, nicotine, or all three substances on likelihood to DUI and RWID. Multilevel logistic models assessed the associations of varied combinations of substances with the daily likelihood of DUI and RWID.

RESULTS

Compared to students who only used alcohol, students who also reported marijuana use were more likely to DUI (OR = 5.44), and students who reported use of alcohol, nicotine and marijuana more likely to DUI (OR = 10.33) and RWID (OR = 10.22). Compared to occasions when only alcohol was used, DUI was more likely on marijuana only occasions (OR = 9.08), and RWID was more likely on alcohol and marijuana occasions (OR = 3.86). However, confidence intervals were wide for effects.

DISCUSSION

Students reporting use of all 3 substances had higher overall risk of DUI and RWID indicating prevention efforts for DUI and RWID should include all substances. Implications for prevention and intervention strategies at the individual and environmental level are discussed.

Impact of co-ingestion of ethanol on the clinical symptomatology and severity of patients attended in the emergency department for recreational drug toxicity

OBJECTIVE

Investigate whether there are differences in the drugs involved, symptomatology and severity of drug intoxication in patients with co-ingestion of alcohol attended in hospital emergency departments (ED).

METHOD

Patients attended in 11 Spanish EDs due to drug intoxication were included. Sociodemographic and clinical characteristics were collected. A combined adverse event of cardiorespiratory arrest, need for intubation, and admission to intensive care or death was considered as the primary indicator of severity. The symptomatology and severity were compared adjusted for age, sex and type of drug based on whether or not ethanol had been co-ingested.

RESULTS

3925 patients (alcohol co-ingestion: 2290, 58.3%) with a mean age of 33 (±11) years were included, and 25% were women. Co-ingestion of alcohol was observed in younger patients, in EDs in areas with high leisure tourism, on holidays and during the early morning hours. It was also more frequent in individuals intoxicated by amphetamine derivatives (66.2%) and cocaine (65.7%), and was more frequently associated with a reduction in consciousness (odds ratio [OR] = 2.13, 95% confidence interval [CI] 1.69-2.67) and agitation/aggressiveness (OR = 1.22, 95% = 1.04-1.43). A combined adverse event was observed in 114 patients (2.9%) with no differences between individuals co-ingesting or not ethanol (3.1% vs. 2.7%; OR = 1.11, 95% CI = 0.74-1.65).

CONCLUSION

Co-ingestion of alcohol is more frequent in individuals intoxicated by cocaine and amphetamines and predisposes a greater reduction in the level of consciousness or agitation, although there are no differences in the severity of the episodes of drug intoxication.

Early and Late Adolescent Factors that Predict Co-use of Cannabis with Alcohol and Tobacco in Young Adulthood

The changing legal landscape of cannabis in the USA has coincided with changes in how cannabis is used, including its co-use with other substances. This study analyzed 10 years of data from a diverse cohort of youth (N = 2429; 54% Hispanic, 16% Asian, 16% white, 3% black, 10% multiracial) to examine predictors in early and late adolescence of co-use of alcohol with cannabis (AC) and tobacco with cannabis (TC) at age 21. Two forms of co-use were examined: concurrent (use of both substances in past month) and sequential (use of one substance right after the other). Analyses focused on four predictor domains: individual (e.g., resistance self-efficacy), peer (e.g., time spent around peers who use), family (e.g., sibling use), and neighborhood (i.e., perceived alcohol and drug problems in neighborhood). For each co-use combination (AC or TC), we estimated parallel process piecewise latent growth models in a structural equation modeling framework using Mplus v8. The final AC and TC co-use models included all predictor variables from the four domains. Increases in positive expectancies and time spent around peers who use AC, as well as steeper decreases in resistance self-efficacy, were all related to a greater likelihood of AC co-use in young adulthood. Increases in sibling TC use and time spent around peers who use TC, as well as steeper decreases in resistance self-efficacy, were all related to a greater likelihood of TC co-use in young adulthood. Overall, findings highlight the importance of addressing peer influence in prevention programming during both early and late adolescence.

Duration of Neurocognitive Impairment With Medical Cannabis Use: A Scoping Review

While the recreational use of cannabis has well-established dose-dependent effects on neurocognitive and psychomotor functioning, there is little consensus on the degree and duration of impairment typically seen with medical marijuana use. Compared to recreational cannabis users, medical cannabis patients have distinct characteristics that may modify the presence and extent of impairment. The goal of this review was to determine the duration of acute neurocognitive impairment associated with medical cannabis use, and to identify differences between medical cannabis patients and recreational users. These findings are used to gain insight on how medical professionals can best advise medical cannabis patients with regards to automobile driving or safety-sensitive tasks at work. A systematic electronic search for English language randomized controlled trials (RCTs), clinical trials and systematic reviews (in order to capture any potentially missed RCTs) between 2000 and 2019 was conducted through Ovid MEDLINE and EMBASE electronic databases using MeSH terms. Articles were limited to medical cannabis patients using cannabis for chronic non-cancer pain or spasticity. After screening titles and abstracts, 37 relevant studies were subjected to full-text review. Overall, seven controlled trials met the inclusion/exclusion criteria and were included in the qualitative synthesis: six RCTs and one observational clinical trial. Neurocognitive testing varied significantly between all studies, including the specific tests administered and the timing of assessments post-cannabis consumption. In general, cognitive performance declined mostly in a THC dose-dependent manner, with steady resolution of impairment in the hours following THC administration. Doses of THC were lower than those typically reported in recreational cannabis studies. In all the studies, there was no difference between any of the THC groups and placebo on any neurocognitive measure after 4 h of recovery. Variability in the dose-dependent relationship raises the consideration that there are other important factors contributing to the duration of neurocognitive impairment besides the dose of THC ingested. These modifiable and non-modifiable factors are individually discussed.

Long-Term Substance Use Can Cause Irreversible Photopic Vision Changes in Substance Use Disorder in Remission

OBJECTIVE

Substance use has such effects on pupil diameter. Although there is knowledge about the acute effects of substances on pupils, studies showing their chronic effects are limited. The aim of the present study was to evaluate the effect of long-term substance use on scotopic, mesopic, and photopic vision.

METHODS

The present study with cross-sectional desgn was conducted at the Adiyaman Training and Research Hospital for Psychiatry in Adiyaman. This study involved 110 substance use disorder (SUD) patients and 46 healthy volunteers as the control. The parameters were measured and recorded automatically by a device.

RESULTS

The mean age was 23.44±5.53 years in the SUD group and 24.26±5.38 years in healthy controls (p=0.420). The mean age of onset of the substance was 17.74±3.89 years and the mean duration of substance use was 3.54±2.9 years. It was determined that the patients had not used any substance for a mean of 121.73±117.49 days. There was no significant difference between patient and control groups in terms of scotopic and mesopic measurements of both eyes (p>0.05). Photopic measurements were significantly higher in the patient group than in the control group (p<0.05). Photopic measurements were significantly higher in the opioid, cannabis, ecstasy, and multiple substance use groups than in the control group (p<0.05).

CONCLUSION

The most important topic of this study is that photopic vision is permanently impaired in patients with a history of chronic substance use. This was attributed to disrupted sympathetic-parasympathetic hierarchy.

Cannabinoids and the eye

Cannabis ranks among the most commonly used psychotropic drugs worldwide. In the context of the global movement toward more widespread legalisation, there is a growing need toward developing a better understanding of the physiological and pathological effects. We provide an overview of the current evidence on the effects of cannabinoids on the eye. Of the identified cannabinoids, Δ⁹-tetrahydrocannabinol is recognized to be the primary psychotropic compound, and cannabidiol is the predominant nonpsychoactive ingredient. Despite demonstrating ocular hypotensive and neuroprotective activity, the use of cannabinoids as a treatment for glaucoma is limited by a large number of potential systemic and ophthalmic side effects. Anterior segment effects of cannabinoids are complex, with preliminary evidence showing decreased corneal endothelial density in chronic cannabinoid users. Experiments in rodents, however, have shown potential promise for the treatment of ocular surface injury via antinociceptive and antiinflammatory effects. Electroretinography studies demonstrating adverse effects on photoreceptor, bipolar, and ganglion cell function suggest links between cannabis and neuroretinal dysfunction. Neuro-ophthalmic associations include ocular motility deficits and decrements in smooth pursuit and saccadic eye movements, although potential therapeutic effects for congenital and acquired nystagmus have been observed.

Cannabis-impaired driving and Canadian youth

Acute cannabis use results in inattention, delayed information processing, impaired coordination, and slowed reaction time. Driving simulator studies and epidemiologic analyses suggest that cannabis use increases motor vehicle crash risk. How much concern should we have regarding cannabis associated motor vehicle collision risks among younger drivers? This article summarizes why young, inexperienced drivers may be at a particularly high risk of crashing after using cannabis. We describe the epidemiology of cannabis use among younger drivers, why combining cannabis with alcohol causes significant impairment and why cannabis edibles may pose a heightened risk to traffic safety. We provide recommendations for clinicians counselling younger drivers about cannabis use and driving.

Illicit drugs: Effects on eye

There is a myriad of changes that can be produced in the eye by toxic drugs ranging from mild/no symptoms to severe loss of vision from endophthalmitis. The routes of administration include oral ingestion, smoking, nasal inhalation, intravenous injection, topical application or application to other mucosal surfaces. It is important to recognize certain clinical signs and symptoms in the eye produced by these toxins. This article describes in brief some of the ocular effects of commonly abused drugs. For identification of a particular poisoning, in addition to the clinical presentation, pulse, blood pressure, respiration and body temperature, pupillary size, pupillary reaction to light, ocular convergence and nystagmus can be useful indicators of the type of drug the patient is exposed to. Unmasking these features help the clinician in an early and accurate diagnosis of the offending drug as well as timely management.

Odds of culpability associated with use of impairing drugs in injured drivers in Victoria, Australia

Culpability analysis was conducted on 5000 drivers injured as a result of a vehicular collision and in whom comprehensive toxicology testing in blood was conducted. The sample included 1000 drivers for each of 5 years from approximately 5000-6000 drivers injured and taken to hospital in the State of Victoria. Logistic regression was used to investigate differences in the odds of culpability associated with alcohol and drug use and other selected crash attributes using the drug-free driver as the reference group. Adjusted odds ratios were obtained from multivariable logistic regression models in which other potentially explanatory driver and crash attributes were included. Drivers with alcohol present showed large increases in the odds of culpability similar to that seen in other studies investigating associations between blood alcohol concentration and crash risk. Methylamphetamine also showed a large increase in the odds of culpability (OR 19) compared to the reference group at both below and above 0.1 mg/L, whereas those drivers with Δ⁹-tetrahydrocannabinol (THC) present showed only modest increase in odds when all concentrations were assessed (OR 1.9, 95 %CI 1.2-3.1). Benzodiazepines in drivers also gave an increase in odds (3.2, 95 %CI 1.6-6.1), but not other medicinal drugs such as antidepressants, antipsychotics and opioids. Drivers that had combinations of impairing drugs generally gave a large increase in odds, particularly combinations of alcohol with THC or benzodiazepines, and those drivers using both THC and methamphetamine.

More drugs, more problems? Simultaneous use of alcohol and marijuana at parties among youth and young adults

BACKGROUND

Simultaneous alcohol and marijuana (SAM) use by youth and young adults often occurs at parties and may result in an increased risk of experiencing adverse consequences compared to use of either substance alone. This study sought to examine the relationship between SAM use by youth and young adults and consequences experienced at, or immediately following, parties.

METHODS

We conducted a repeated cross-sectional survey of 15 to 20-year-olds residing in 24 communities across seven states within the United States in 2015 and 2016 (n = 2681). Logistic regression analyses were used to examine associations between SAM use and six consequences (e.g. hangover, sex without a condom, involved in a fight) among 834 youth and young adults (53.7% female, 78.3% White, mean age: 18.4 years) who reported using either alcohol or marijuana at the last party they attended.

RESULTS

72.3% consumed alcohol exclusively, 5.2% used marijuana exclusively, and 22.5% engaged in SAM use. In multivariable analyses, those who reported SAM use had significantly greater odds of experiencing any (AOR = 1.9; 95% CI: 1.3, 2.8) and 2 or more (AOR = 4.0; 95% CI: 2.0, 8.0) consequences compared to those who used only alcohol.

CONCLUSIONS

Our findings suggest that SAM use in a party context is associated with an increased risk of experiencing consequences among youth and young adults after controlling for the quantity of alcohol consumed. Policy and educational prevention strategies should target SAM at parties to reduce harms among youth and young adults.

Alcohol, tobacco, and marijuana consumption is associated with increased odds of same-day substance co- and tri-use

BACKGROUND

Little is known about event-level patterns of marijuana co- or tri-use with alcohol and tobacco. Thus, the study goal was to examine patterns of same-day alcohol, cigarette, and marijuana co- and tri-use at the individual level in non-treatment-seeking alcohol users.

METHODS

Participants (N = 551) completed an in-person interview for alcohol, cigarette, and marijuana use over the previous 30 days, and the event-level substance use patterns of n = 179 participants who reported using each of these substances at least once per month were analyzed.

RESULTS

The use of alcohol, marijuana, or cigarettes independently increased the probability of subsequent, simultaneous co-use of one of the two remaining substances. The co-use of alcohol with cigarettes and marijuana with cigarettes produced generally additive effects on the odds of same day tri-use of marijuana and alcohol, respectively. Conversely, the co-use of alcohol and marijuana produced sub-additive effects on likelihood of cigarette use. Sex moderated several of the observed patterns of co- and tri-use: the relationship between alcohol or cigarette use predicting marijuana co-use was stronger in men, whereas the observed additive relationships between drug co-use leading to tri-use was stronger in women.

CONCLUSIONS

The presented results may aid in the understanding of how simultaneous co-use of marijuana with alcohol and/or tobacco relates to the etiology, maintenance, and treatment of comorbid and trimorbid substance use disorder. Replication and extension of the results in treatment seeking populations using more fine-grained analysis approaches, e.g. ecological momentary assessment, is needed.

Association between speeding and use of alcohol and medicinal and illegal drugs and involvement in road traffic crashes among motor vehicle drivers

OBJECTIVE

The objective of this study was to study the association between self-reported road traffic crashes (RTCs) and recent use of alcohol and medicinal and illicit drug use and self-reported speeding in the previous 2 years.

METHODS

During the period from April 2016 to April 2017, drivers of cars, vans, motorcycles, and mopeds were stopped in a Norwegian roadside survey performed in collaboration with the police. Participation was voluntary and anonymous. The drivers were asked to deliver an oral fluid sample (mixed saliva), which was analyzed for alcohol and 39 illicit and medicinal drugs and metabolites. In addition, data on age, sex, and self-reported speeding tickets and RTCs during the previous 2 years were collected.

RESULTS

A total of 5,031 participants were included in the study, and 4.9% tested positive for the use of one or more illicit or medicinal drugs or alcohol. We found a significant, positive association between the use of cannabis and RTC involvement (odds ratio [OR] = 1.93; 95% confidence interval [CI], 1.05-3.57; P = 0.035) and also between previous speeding tickets and RTC involvement (OR = 1.39; 95% CI, 1.08-1.80; P = 0.012). In addition, older age groups were found to have a significant, negative association with RTC involvement, with ORs equal to or less than 0.49, when using the age group 16-24 as reference.

CONCLUSION

Speeding, as an indicator of risk behavior, and the use of cannabis were associated with previous RTC involvement, whereas increasing age was significantly associated with lower risk. This is consistent with previous studies on RTCs.

Differences in alcohol cognitions, consumption, and consequences among first-time DUI offenders who co-use alcohol and marijuana

BACKGROUND

A significant portion of alcohol-related DUI offenders engage in co-use of alcohol and marijuana (AM). Given expanding marijuana legalization and the impaired driving risks associated with co-use, it is of increased importance to understand how characteristics of AM co-users compare to those who use alcohol only (AO) in order to inform DUI interventions and prevent recidivism.

METHODS

Participants were 277 first-time DUI offenders enrolled in a first-time DUI offender program across three locations. Using well-established measures, we evaluated differences in alcohol-related cognitions (positive expectancies and self-efficacy), frequency and quantity of alcohol consumption, and alcohol-related consequences between AO users and AM co-users by running a series of multivariate generalized linear models.

RESULTS

Compared to AO users, AM co-users reported lower self-efficacy to achieve abstinence and avoid DUI. Differences in abstinence self-efficacy largely explain higher relative rates of average and peak drinking quantity and higher odds of binge drinking among AM co-user. Despite lower self-efficacy and higher drinking quantity, there were no significant differences between AM and AO-users on alcohol-related consequences and past month reports of drinking and driving.

CONCLUSIONS

Our results provide preliminary evidence that DUI offenders who co-use alcohol and marijuana have higher alcohol use and lower self-efficacy than AO-users, and long-term consequences for this group should be monitored in future research. DUI programs may screen and identify co-users and consider tailoring their interventions to build self-efficacy to address the risks associated with AM co-use uniquely.

Location, location, location: Assessing the spatial patterning between marijuana licenses, alcohol outlets and neighborhood characteristics within Washington state

BACKGROUND

The availability of marijuana products is becoming increasingly prevalent across the United States (US), many states are allowing for the production, processing, and retailing of these products for medical and/or recreational use. The purpose of this study is to: (1) examine the spatial patterning of marijuana licenses, and (2) examine the impact of alcohol outlets in addition to other neighborhood characteristics on marijuana licenses within the state of Washington.

METHODS

This cross-sectional observational study examined 1458 census tracts in Washington state from 2017, using marijuana and alcohol data from the Washington State Liquor and Cannabis Board as well as neighborhood characteristics data from the American Community Survey 2011-2015 5-year estimates. We used exploratory and formal spatial regression methods, including integrated nested Laplace approximation within a Bayesian statistical framework, to address the study aims.

RESULTS

Our results indicate there is significant spatial patterning of marijuana producers and processors across the state. We also found that all marijuana licenses are located in poorer census tracts, and marijuana retailers are co-located in census tracts with off-premises alcohol outlets.

CONCLUSIONS

Our study provides empirical evidence of the relationship between marijuana licenses, alcohol outlets, and neighborhood characteristics, and has important implications for policymakers in other states currently considering legalizing marijuana-products for medical and/or recreational use.

Correlation between Blood and Oral Fluid Psychoactive Drug Concentrations and Cognitive Impairment in Driving under the Influence of Drugs

BACKGROUND

The effects of drugs on driving performance should be checked with drug concentration in the brain and at the same time with the evaluation of both the behavioural and neurophysiological effects. The best accessible indicator of this information is the concentration of the drug and/or metabolites in blood and, to a certain extent, oral fluid. We sought to review international studies on correlation between blood and oral fluid drug concentrations, neurological correlates and cognitive impairment in driving under the influence of drugs.

METHODS

Relevant scientific articles were identified from PubMed, Cochrane Central, Scopus, Web of Science, Science Direct, EMBASE up to April 2017.

RESULTS

Up to 2010, no epidemiological studies were available on this matter and International scientists suggested that even minimal amounts of parent drugs in blood and oral fluid could affect driving impairment. More recently, epidemiological data, systematic reviews and meta-analysis on drugged drivers allowed the suggestion of impairment concentration limits for the most common illicit drugs. These values were obtained comparing driving disability induced by psychotropic drugs with that of established blood alcohol limits. Differently from ethyl alcohol where both detection methods and concentration limits have been well established even with inhomogeneity of ranges within different countries, in case of drugs of abuse no official cut-offs have yet been established, nor any standardized analytical protocols.

CONCLUSION

Multiple aspects of driving performance can be differently affected by illicit drugs, and even if for few of them some dose/concentration dependent impairment has been reported, a wider knowledge on concentration/impairment relationship is still missing.

Interaction of marijuana and alcohol on fatal motor vehicle crash risk: a case-control study

BACKGROUND

Concurrent use of marijuana and alcohol in drivers is of increasing concern but its role in crash causation has not been well understood.

METHODS

Using a case-control design, we assessed the individual and joint effects of marijuana and alcohol use on fatal crash risk. Cases (n = 1944) were drivers fatally injured in motor vehicle crashes in the United States at specific times in 2006, 2007 and 2008. Controls (n = 7719) were drivers who participated in the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers.

RESULTS

Overall, cases were significantly more likely than controls to test positive for marijuana (12.2% vs. 5.9%, p < 0.0001), alcohol (57.8% vs. 7.7%, p < 0.0001) and both marijuana and alcohol (8.9% vs. 0.8%, p < 0.0001). Compared to drivers testing negative for alcohol and marijuana, the adjusted odds ratios of fatal crash involvement were 16.33 [95% confidence interval (CI): 14.23, 18.75] for those testing positive for alcohol and negative for marijuana, 1.54 (95% CI: 1.16, 2.03) for those testing positive for marijuana and negative for alcohol, and 25.09 (95% CI: 17.97, 35.03) for those testing positive for both alcohol and marijuana.

CONCLUSIONS

Alcohol use and marijuana use are each associated with significantly increased risks of fatal crash involvement. When alcohol and marijuana are used together, there exists a positive synergistic effect on fatal crash risk on the additive scale.

Oral fluid testing for marijuana intoxication: enhancing objectivity for roadside DUI testing

Reducing marijuana-impaired driving is an important part of any strategy to prevent motor vehicle traffic injuries. In Colorado, the first of eight US states and the District of Columbia to legalise marijuana for recreational use, drivers with positive tests for the presence of marijuana accounted for a larger proportion of fatal MVCs after marijuana commercialisation. The use of blood tests to screen for marijuana intoxication, in Colorado and elsewhere in the USA, poses a number of challenges. Many high-income countries use oral fluid drug testing (OF) to provide roadside evidence of marijuana intoxication. A 2009 Belgium policy implementing OF roadside testing increased true positives and decreased false positives of suspected marijuana-related driving under the influence (DUI) arrests. US policy-makers should consider using roadside OF to increase objectivity and reliability for tests used in marijuana-related DUI arrests.

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.

High-intensity cannabis use and HIV clinical outcomes among HIV-positive people who use illicit drugs in Vancouver, Canada

BACKGROUND

Reforms to the legal status of medical and non-medical cannabis are underway in many jurisdictions, including Canada, as are renewed efforts to scale-up HIV treatment-as-prevention (TasP) initiatives. It has been suggested that high-intensity cannabis use may be associated with sub-optimal HIV treatment outcomes. Thus, using data from a setting with a community-wide treatment-as-prevention (TasP) initiative coinciding with increasing access to medical cannabis, we sought to investigate the possible impact of high-intensity cannabis use on HIV clinical outcomes.

METHODS

Data was derived from the ACCESS study, a prospective cohort of HIV-positive people who use illicit drugs (PWUD) in Vancouver, Canada. Cohort data was confidentially linked to comprehensive clinical profiles, including records of all antiretroviral therapy (ART) dispensations and longitudinal plasma HIV-1 RNA viral load (VL) monitoring. We used generalized estimating equations (GEEs) to estimate the longitudinal bivariable and multivariable relationships between at least daily cannabis use and two key clinical outcomes: overall engagement in ART care, and achieving a non-detectable VL among ART-exposed participants.

RESULTS

Between December 2005 and June 2015, 874 HIV-positive PWUD (304 [35%] non-male) were included in this study. In total, 788 (90%) were engaged in HIV care at least once over the study period, of whom 670 (85%) achieved non-detectable VL at least once. In multivariable analyses, ≥ daily cannabis use did not predict lower odds of ART care (Adjusted Odds Ratio [AOR]: 1.02, 95% confidence interval [CI]: 0.77-1.36) or VL non-detectability among ART-exposed (AOR: 0.96, 95% CI: 0.75-1.21). Upon testing for potential interactions, ≥ daily cannabis use was found to be negatively associated with ART engagement during periods of binge alcohol use (p<0.05).

CONCLUSION

With the exception of frequent cannabis use during periods of binge alcohol use, our results showed no statistically significant impact of daily cannabis use on the likelihood of ART care or VL non-detectability among ART-exposed HIV-positive PWUD. These findings are reassuring in light of the impending legalization of cannabis in Canada and ongoing efforts to expand TasP initiatives.

DUID prevalence in Colorado's DUI citations

INTRODUCTION

There are limited studies that measure the prevalence of driving under the influence of drugs (DUID) based upon impairment measures because most prevalence studies are based on drug tests. The aim of this study was to provide the first estimate of DUID prevalence in Colorado using data collected by Colorado law enforcement officers in vehicular homicide (VH) and vehicular assault (VA) cases, and reported in court records.

METHODS

The four research questions of this study were answered by completing independent t-tests or Mann-Whitney U tests, Pearson chi-square analyses or Fisher's exact tests, and Kruskal-Wallis tests.

RESULTS

Seventy percent (119 out of 170) of the cases involved alcohol only and 30% (51 out of 170) involved drugs. Of the latter cases, 32 cases involved a combination of alcohol and drugs and 19 cases identified drugs only, with no alcohol. Marijuana was the most commonly cited drug (23 cases); however, it was the sole impairing substance identified in only three cases.

CONCLUSION

Polydrug use was very common among DUID cases, which makes it difficult to identify which drug or drugs caused the impairment responsible for the Driving Under the Influence citation. This study revealed tha (a) drugged driving is a frequent cause of DUI citations in cases charged with VH or VA; (b) that polydrug use, rather than marijuana, is the most common cause of drugged driving in Colorado; and (c) that current warrant procedures render blood test results meaningless in cases of marijuana-impairment.

PRACTICAL APPLICATION

States should collect and analyze DUID data to ensure legislators focus on the right DUID problems to improve biological testing for drugs, adopt more appropriate roadside testing, and enact stronger DUID laws to protect the public.

Simultaneous versus concurrent use of alcohol and cannabis in the National Alcohol Survey

BACKGROUND

Cannabis is the most commonly used drug among those who drink, yet no study has directly compared those who use cannabis and alcohol simultaneously versus concurrently (i.e., separately) in the adult general population. Here, we assess differences in demographics, alcohol-related social consequences, harms to self, and drunk driving across simultaneous, concurrent, and alcohol-only using groups.

METHODS

Secondary analyses of the 2005 and 2010 National Alcohol Survey (N = 8,626; 4,522 female, 4,104 male), a Computer Assisted Telephone Interview survey of individuals aged 18 and older from all 50 states and DC. Blacks and Hispanics are over-sampled. Data were collected using list-assisted Random Digit Dialing. Multinomial and multivariable logistic regressions were used for analyses.

RESULTS

The prevalence of simultaneous use was almost twice as high as concurrent use, implying that individuals who use both cannabis and alcohol tend to use them at the same time. Furthermore, simultaneous use was associated with increased frequency and quantity of alcohol use. Simultaneous use was also the most detrimental: compared to alcohol only, simultaneous use approximately doubled the odds of drunk driving, social consequences, and harms to self. The magnitudes of differences in problems remained when comparing drunk driving among simultaneous users to concurrent users.

CONCLUSIONS

The overall set of results is particularly important to bear in mind when studying and/or treating problems among alcohol/cannabis co-users because they demonstrate that in the general population, co-users are a heterogeneous group who experience different likelihoods of problems relative to co-use patterns.

Cannabinoid Ligands and Alcohol Addiction: A Promising Therapeutic Tool or a Humbug?

The vast therapeutic potential of cannabinoids of both synthetic and plant-derived origins currently makes these compounds the focus of a growing interest. Although cannabinoids are still illicit drugs, their possible clinical usefulness, including treatment of acute or neuropathic pain, have been suggested by several studies. In addition, some observations indicate that cannabinoid receptor antagonists may be useful for the treatment of alcohol dependence and addiction, which is a major health concern worldwide. While the synergism between alcohol and cannabinoid agonists (in various forms) creates undesirable side effects when the two are consumed together, the administration of CB1 antagonists leads to a significant reduction in alcohol consumption. Furthermore, cannabinoid antagonists also mitigate alcohol withdrawal symptoms. Herein, we present an overview of studies focusing on the effects of cannabinoid ligands (agonists and antagonists) during acute or chronic consumption of ethanol.

Comprehensive Review of Medicinal Marijuana, Cannabinoids, and Therapeutic Implications in Medicine and Headache: What a Long Strange Trip It's Been …

BACKGROUND

The use of cannabis, or marijuana, for medicinal purposes is deeply rooted though history, dating back to ancient times. It once held a prominent position in the history of medicine, recommended by many eminent physicians for numerous diseases, particularly headache and migraine. Through the decades, this plant has taken a fascinating journey from a legal and frequently prescribed status to illegal, driven by political and social factors rather than by science. However, with an abundance of growing support for its multitude of medicinal uses, the misguided stigma of cannabis is fading, and there has been a dramatic push for legalizing medicinal cannabis and research. Almost half of the United States has now legalized medicinal cannabis, several states have legalized recreational use, and others have legalized cannabidiol-only use, which is one of many therapeutic cannabinoids extracted from cannabis. Physicians need to be educated on the history, pharmacology, clinical indications, and proper clinical use of cannabis, as patients will inevitably inquire about it for many diseases, including chronic pain and headache disorders for which there is some intriguing supportive evidence.

OBJECTIVE

To review the history of medicinal cannabis use, discuss the pharmacology and physiology of the endocannabinoid system and cannabis-derived cannabinoids, perform a comprehensive literature review of the clinical uses of medicinal cannabis and cannabinoids with a focus on migraine and other headache disorders, and outline general clinical practice guidelines.

CONCLUSION

The literature suggests that the medicinal use of cannabis may have a therapeutic role for a multitude of diseases, particularly chronic pain disorders including headache. Supporting literature suggests a role for medicinal cannabis and cannabinoids in several types of headache disorders including migraine and cluster headache, although it is primarily limited to case based, anecdotal, or laboratory-based scientific research. Cannabis contains an extensive number of pharmacological and biochemical compounds, of which only a minority are understood, so many potential therapeutic uses likely remain undiscovered. Cannabinoids appear to modulate and interact at many pathways inherent to migraine, triptan mechanisms ofaction, and opiate pathways, suggesting potential synergistic or similar benefits. Modulation of the endocannabinoid system through agonism or antagonism of its receptors, targeting its metabolic pathways, or combining cannabinoids with other analgesics for synergistic effects, may provide the foundation for many new classes of medications. Despite the limited evidence and research suggesting a role for cannabis and cannabinoids in some headache disorders, randomized clinical trials are lacking and necessary for confirmation and further evaluation.

Impact of age at onset of cannabis use on cannabis dependence and driving under the influence in the United States

BACKGROUND AND AIMS

There is growing evidence that driving under the influence of cannabis is associated with a higher risk of motor vehicle crash. Cannabis dependence has been reported to be associated with a three-fold increased risk of motor vehicle crash. The impact of the age at onset of cannabis use on the risk of both cannabis dependence and driving under the influence of cannabis has not been evaluated so far.

METHODS

Data were drawn from the 2001-2002 National Epidemiological Survey on Alcohol and Related Conditions (NESARC), a survey of 43,093 adults aged 18 years and older. We limited our analyses to the sample of participants who reported having ever used cannabis (n=8172), of whom 8068 had a known age at onset of cannabis use.

RESULTS

Of the 8068 participants included, 5.15% reported having driven under the influence of cannabis. Among those, only a minority (14.46%) were diagnosed with cannabis dependence. Compared to those who start using cannabis at age 21 years or after, participants who used cannabis before the age of 14 years were 4 times more likely to have a history of cannabis dependence and 3 times more likely to reported having driven under the influence of cannabis. An inverse relationship between the age at onset of cannabis use and driving under the influence and risk of cannabis dependence was found.

CONCLUSIONS

Starting to smoke cannabis younger than 21 years is associated with both cannabis dependence and driving under the influence of cannabis.

Medical marijuana: review of the science and implications for developmental-behavioral pediatric practice

Marijuana policy is rapidly evolving in the United States and elsewhere, with cannabis sales fully legalized and regulated in some jurisdictions and use of the drug for medicinal purposes permitted in many others. Amidst this political change, patients and families are increasingly asking whether cannabis and its derivatives may have therapeutic utility for a number of conditions, including developmental and behavioral disorders in children and adolescents. This review examines the epidemiology of cannabis use among children and adolescents, including those with developmental and behavioral diagnoses. It then outlines the increasingly well-recognized neurocognitive changes shown to occur in adolescents who use cannabis regularly, highlighting the unique susceptibility of the developing adolescent brain and describing the role of the endocannabinoid system in normal neurodevelopment. The review then discusses some of the proposed uses of cannabis in developmental and behavioral conditions, including attention-deficit hyperactivity disorder and autism spectrum disorder. Throughout, the review outlines gaps in current knowledge and highlights directions for future research, especially in light of a dearth of studies specifically examining neurocognitive and psychiatric outcomes among children and adolescents with developmental and behavioral concerns exposed to cannabis.

The relationship between observed signs of impairment and THC concentration in oral fluid

BACKGROUND

Studies have shown that cannabis intake increases the risk of traffic accidents. Controlled experiments support these findings and have shown a positive dose-effect relationship.

METHODS

In this retrospective cross-sectional study of data from a roadside survey, we investigated whether a police officer's judgment regarding signs of impairment is related to the concentration of delta-9-tetrahydrocannabinol (THC) in the oral fluid (OF). We investigated 2,632 cases from a representative sample of 3,302 Spanish drivers: 253 drivers positive for THC only, 32 positive for THC and ethanol, 201 with only ethanol detected in their breath, and 2,146 drivers who tested negative for ethanol in breath and drugs in OF. Recorded data comprised breath alcohol concentrations, THC concentrations in the OF, and the 31 observed signs of impairment. Subject groups were compared using the chi-square test, and logistic regression was used to examine the risk of being categorized as exhibiting signs of impairment.

RESULTS

A relationship was found between the OF THC concentration and some observed signs of impairment. Eye signs were noticeable from a THC concentration >3.0 ng/ml in OF, and >25 ng/ml was related to behavior, facial expression, and speech signs. Alcohol and THC contribute to impairment independently and, when taken simultaneously, the effects are comparable to the sum of the effects when consumed separately.

CONCLUSIONS

The observation of signs of impairment due to cannabis occurs in an OF concentration-related manner but, as a clinical test, OF has low sensitivity and specificity in a random roadside survey.

Youth marijuana use: state of the science for the practicing clinician

PURPOSE OF REVIEW

Despite widespread marijuana use among adolescents, accurate information on known health effects is poorly disseminated to clinicians and their patients. Amidst rapidly evolving drug policy in the United States and elsewhere, it is imperative that providers understand the short-term and long-term consequences of marijuana use.

RECENT FINDINGS

Research on regular marijuana use highlights a unique susceptibility of the developing adolescent brain to adverse neurocognitive and psychiatric outcomes. Although studies have not firmly established causality, onset of regular marijuana use in adolescence is associated with later decline in cognitive function, as well as with adult onset of psychosis and anxiety. Educational and employment outcomes may be poorer among regular marijuana-using adolescents. A number of other adverse respiratory, cardiovascular, endocrine and gastrointestinal associations with regular marijuana use have also been established. Good screening tools and promising brief intervention and behavioral treatment programs are available to clinicians, who are in a position to identify problematic marijuana use among adolescents.

SUMMARY

A common misperception among youth is that marijuana use is without harm. However, adolescent marijuana use may have measurable, durable, and potentially irreversible effects on later cognitive function and mental health.

Trends in fatal motor vehicle crashes before and after marijuana commercialization in Colorado

BACKGROUND

Legal medical marijuana has been commercially available on a widespread basis in Colorado since mid-2009; however, there is a dearth of information about the impact of marijuana commercialization on impaired driving. This study examined if the proportions of drivers in a fatal motor vehicle crash who were marijuana-positive and alcohol-impaired, respectively, have changed in Colorado before and after mid-2009 and then compared changes in Colorado with 34 non-medical marijuana states (NMMS).

METHODS

Thirty-six 6-month intervals (1994-2011) from the Fatality Analysis Reporting System were used to examine temporal changes in the proportions of drivers in a fatal motor vehicle crash who were alcohol-impaired (≥0.08 g/dl) and marijuana-positive, respectively. The pre-commercial marijuana time period in Colorado was defined as 1994-June 2009 while July 2009-2011 represented the post-commercialization period.

RESULTS

In Colorado, since mid-2009 when medical marijuana became commercially available and prevalent, the trend became positive in the proportion of drivers in a fatal motor vehicle crash who were marijuana-positive (change in trend, 2.16 (0.45), p<0.0001); in contrast, no significant changes were seen in NMMS. For both Colorado and NMMS, no significant changes were seen in the proportion of drivers in a fatal motor vehicle crash who were alcohol-impaired.

CONCLUSIONS

Prevention efforts and policy changes in Colorado are needed to address this concerning trend in marijuana-positive drivers. In addition, education on the risks of marijuana-positive driving needs to be implemented.

The culpability of drivers killed in New Zealand road crashes and their use of alcohol and other drugs

Over a period of five years, blood samples were taken from 1046 drivers killed as a result of a motor vehicle crash on New Zealand roads. These were analysed for the presence of alcohol and a range of both illicit drugs and psychoactive medicinal drugs. Driver culpability was determined for all crashes. The control group of drug- and alcohol-free drivers comprised 52.2% of the study population. Drivers positive for psychoactive drugs were more likely to be culpable (odds ratio (OR) 3.5, confidence interval (CI) 95% 2.4-5.2) than the control group. Driver culpability exhibited the expected positive association with alcohol use (OR 13.7, 95% CI 4.3-44) and with combined alcohol and cannabis use (OR 6.9, 95% CI 3.0-16). There was only a weak positive association between cannabis use (with no other drug) and culpability (OR 1.3, CI 95% 0.8-2.3). Furthermore, the OR for drivers with blood tetrahydrocannabinol (THC) concentrations greater than 5 ng/mL was lower (OR 1.0, CI 95% 0.4-2.4) than drivers with blood THC concentrations less than 2 ng/mL (OR 3.1, CI 95% 0.9-10). This is inconsistent with results reported by other studies where a significant increase in crash risk was found with blood THC levels greater than 5 ng/mL. In this study, there were very few drivers who had used a single drug, other than cannabis or alcohol. Therefore, from this study, it is not possible to comment on any relationship between opioid, stimulant or sedative drug use and an increased risk of being killed in a crash for the drivers using these drugs. The results from a multivariate analysis indicate that driver gender, age group and licence status, (P=0.022, P=0.016, P=0.026, respectively), the type of vehicle being driven (P=0.013), the number of vehicles in the crash (P<0.001), the blood alcohol concentration of the driver (P<0.001) and the use of any drug other than alcohol and cannabis (P=0.044), are all independently associated with culpability.

Developing public health regulations for marijuana: lessons from alcohol and tobacco

Until November 2012, no modern jurisdiction had removed the prohibition on the commercial production, distribution, and sale of marijuana for nonmedical purposes-not even the Netherlands. Government agencies in Colorado and Washington are now charged with granting production and processing licenses and developing regulations for legal marijuana, and other states and countries may follow. Our goal is not to address whether marijuana legalization is a good or bad idea but, rather, to help policymakers understand the decisions they face and some lessons learned from research on public health approaches to regulating alcohol and tobacco over the past century.