Has the intake of THC by cannabis users changed over the last decade? Evidence of increased exposure by analysis of blood THC concentrations in impaired drivers

Drug driving: a secondary analysis of factors associated with driving under the influence of cannabis in Jamaica

OBJECTIVES

To determine cannabis use patterns, the predictive sociodemographic correlates of driving under the influence of cannabis (DUIC) and the association between risk perception and cannabis dependence among vehicle drivers in Jamaica.

DESIGN

Secondary data analysis.

SETTING

Used the Jamaica National Drug Prevalence Survey 2016 dataset.

PARTICIPANTS

1060 vehicle drivers extracted from the population sample of 4623.

PRIMARY AND SECONDARY OUTCOME MEASURES

Analysis used Pearson's χ2 test and logistic regression. ORs and 95% CIs were recorded. A p<0.05 was considered statistically significant.

RESULTS

More than 10% of Jamaican drivers admitted to DUIC in the past year. Approximately 43.3% of drivers who currently use cannabis reported DUIC only. Evidently, 86.8% of drivers who DUIC were heavy cannabis users. Approximately 30% of drivers with moderate to high-risk perception of smoking cannabis sometimes or often were dependent on cannabis. Notwithstanding, drivers with no to low-risk perception of smoking cannabis sometimes or often were significantly likelier to be dependent (p<0.001 and p<0.001, respectively). Logistic regression highlighted male drivers (OR 4.14, 95% CI 1.59 to 14.20, p=0.009) that were 34 years and under (OR 2.97, 95% CI 1.71 to 5.29, p<0.001) and were the head of the household (OR 2.22, 95% CI 1.10 to 4.75, p=0.031) and operated a machine as part of their job (OR 1.87, 95% CI 1.09 to 3.24, p=0.023) were more likely to DUIC, while those who were married (OR 0.42, 95% CI 0.22 to 0.74, p=0.004) and had achieved a tertiary-level education (OR 0.26, 95% CI 0.06 to 0.76, p=0.031) were less likely.

CONCLUSIONS

Two in five Jamaican drivers, who currently smoke cannabis, drive under its influence, with over 85% engaging in heavy use. Public health implications necessitate policy-makers consider mobile roadside drug testing and amending drug-driving laws to meet international standards.

Can inhaled cannabis users accurately evaluate impaired driving ability? A randomized controlled trial

Aims

To study the effect of inhaled cannabis on self-assessed predicted driving ability and its relation to reaction times and driving ability on a driving simulator.

Participants and methods

30 healthy male volunteers aged 18-34: 15 chronic (1-2 joints /day) and 15 occasional (1-2 joints/week) consumers. Self-assessed driving confidence (visual analog scale), vigilance (Karolinska), reaction time (mean reciprocal reaction time mRRT, psychomotor vigilance test), driving ability (standard deviation of lane position SDLP on a York driving simulator) and blood concentrations of delta-9-tétrahydrocannabinol (THC) were measured before and repeatedly after controlled inhalation of placebo, 10 mg or 30 mg of THC mixed with tobacco in a cigarette.

Results

Cannabis consumption (at 10 and 30 mg) led to a marked decrease in driving confidence over the first 2 h which remained below baseline at 8 h. Driving confidence was related to THC dose and to THC concentrations in the effective compartment with a low concentration of 0.11 ng/ml for the EC50 and a rapid onset of action (T1/2 37 min). Driving ability and reaction times were reduced by cannabis consumption. Driving confidence was shown to be related to driving ability and reaction times in both chronic and occasional consumers.

Conclusions

Cannabis consumption leads to a rapid reduction in driving confidence which is related to reduced ability on a driving simulator.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT02061020.

A Comparison of High Drug Concentrations in Impaired Driving and Postmortem Casework in Harris County, Texas

Drug-impaired driving is a growing public safety issue. Addressing impairment due to drugs other than ethanol can be challenging for forensic toxicologists as many factors need to be considered including the type of drug(s), drug-drug interaction, the dose(s), and the individual's physiological condition and drug use history. Interpretation of blood drug test results is additionally difficult as drug concentrations in impaired driving cases may overlap levels typically viewed as toxic. This study compares blood concentrations of drugs in impaired driving cases to those in postmortem cases in Houston, Texas from 2014 to 2020. Blood drug concentrations from driving while intoxicated (DWI) or driving under the influence of drugs (DUID) cases submitted to Houston Forensic Science Center (HFSC) and Harris County Institute of Forensic Sciences (HCIFS) were compared to postmortem blood test results from HCIFS. Eight DWI/DUID cases had drugs that exceeded impaired driving concentrations reported in literature. These drugs included fentanyl (220 ng/mL), oxycodone (680 ng/mL), hydrocodone (310 and 490 ng/mL), clonazepam (330 ng/mL), methamphetamine (3500 and 7100 ng/mL), and THC (160 ng/mL). For oxycodone and hydrocodone, the presented DWI/DUID cases exceeded 91% and 96% of postmortem concentrations, respectively. The 7100 ng/mL methamphetamine DWI/DUID result was greater than 98% of postmortem cases. The presented DWI/DUID concentrations were higher than all but one postmortem case for clonazepam and higher than all postmortem cases for THC. This study demonstrates extremely high drug concentrations in DWI/DUID casework blur the line between therapeutic/recreational and toxic concentrations.

Cannabis Consumption Onset and Addiction: Data from the Second Brazilian Drugs and Alcohol Survey (BNADS)

The objective of this study was to provide rates of cannabis use and dependence and risk factors, proposing a conditional path model for cannabis addiction. A subsample of adult participants from a Brazilian household survey was analyzed to estimate cannabis dependence. Estimation of prevalence rates and association between dependence and age of cannabis use initiation were performed. The conditional model was applied to investigate the mediation of depressive symptoms and alcohol consumption in the association of early cannabis use and dependence. Lifetime and last year cannabis use were 6.47% and 2.81%, respectively. Moderate and severe cannabis dependence were 0.74% and 0.18% in the population, and 26.47% and 6.38% among last year's cannabis users. A Parallel Multiple Mediator Model revealed strong association between cannabis use initiation age and dependence, when depressive symptoms or alcohol consumption mediate this association. The proportion of cannabis users displaying dependence symptoms is elevated and it is associated with the age of cannabis use initiation. The results show the importance of primary prevention interventions, prioritizing the delay of cannabis and alcohol experimentation. Our findings can enrich the debate on drugs policies and legislation, reinforcing the need for stronger restrictions of adolescent drug access and ensuring its enforcement.

When Cannabis Use Goes Wrong: Mental Health Side Effects of Cannabis Use That Present to Emergency Services

Cannabis use is a modifiable risk factor for the development and exacerbation of mental illness. The strongest evidence of risk is for the development of a psychotic disorder, associated with early and consistent use in youth and young adults. Cannabis-related mental health adverse events precipitating Emergency Department (ED) or Emergency Medical Services presentations can include anxiety, suicidal thoughts, psychotic or attenuated psychotic symptoms, and can account for 25-30% of cannabis-related ED visits. Up to 50% of patients with cannabis-related psychotic symptoms presenting to the ED requiring hospitalization will go on to develop schizophrenia. With the legalization of cannabis in various jurisdiction and the subsequent emerging focus of research in this area, our understanding of who (e.g., age groups and risk factors) are presenting with cannabis-related adverse mental health events in an emergency situation is starting to become clearer. However, for years we have heard in popular culture that cannabis use is less harmful or no more harmful than alcohol use; however, this does not appear to be the case for everyone. It is evident that these ED presentations should be considered another aspect of potentially harmful outcomes that need to be included in knowledge mobilization. In the absence of a clear understanding of the risk factors for mental health adverse events with cannabis use it can be instructive to examine what characteristics are seen with new presentations of mental illness both in emergency departments (ED) and early intervention services for mental illness. In this narrative review, we will discuss what is currently known about cannabis-related mental illness presentations to the ED, discussing risk variables and outcomes both prior to and after legalization, including our experiences following cannabis legalization in Canada. We will also discuss what is known about cannabis-related ED adverse events based on gender or biological sex. We also touch on the differences in magnitude between the impact of alcohol and cannabis on emergency mental health services to fairly present the differences in service demand with the understanding that these two recreational substances may impact different populations of individuals at risk for adverse events.

Cannabis Use during Pregnancy and Risk of Adverse Birth Outcomes: A Longitudinal Cohort Study

BACKGROUND

With recent changes in legislation regulating recreational and medical cannabis use around the globe, increased use in pregnancy is to be expected.

OBJECTIVES

To investigate the association between cannabis use during pregnancy and birth outcomes.

METHOD

Data from the Norwegian Mother and Child Cohort Study (MoBa), a prospective pregnancy cohort, were used. Participants were recruited from all over Norway between 1999 and 2008: 9,312 women with 10,373 pregnancies who reported use of cannabis before or in pregnancy. Women reported on their illegal drug use before pregnancy and at pregnancy weeks 17/18 and 30 and at 6 months postpartum. Linear regression was used to estimate crude and adjusted effects of prenatal cannabis exposure on birth outcomes.

RESULTS

In 10,101 pregnancies, women had used cannabis before pregnancy but not during pregnancy. In 272 pregnancies, women had used cannabis during pregnancy, and among these, in 63 pregnancies, women had used cannabis in at least 2 periods. In adjusted analyses for potential confounders, only cannabis use during at least 2 periods of pregnancy showed statistically significant effects on birth weight. The effect was observed in the complete cohort (B = -228 g, 95% CI = -354 to -102, p < 0.001) and for the subgroup where information about the child's father was available (B = -225 g, 95% CI = -387 to -63, p = 0.01). Our results may indicate that prolonged use causes more harm, whereas short-term use did not indicate adverse effects on birth outcomes.

CONCLUSIONS

There was a statistically significant and clinically relevant association between the use of cannabis during pregnancy and reduced birth weight. Clinicians should screen not only for cannabis use but also for the length and intensity of use as part of a comprehensive substance use screening.

Mapping cannabis potency in medical and recreational programs in the United States

Cannabis related online searches are associated with positive attitudes toward medical cannabis, particularly when information is obtained from dispensaries. Since pain is the main reason for medicinal cannabis use, information from dispensary websites has the potential to shape the attitude of pain patients towards cannabis. This is relevant because cannabis has demonstrated efficacy in neuropathic pain with low tetrahydrocannabinol (THC) concentrations (< 5-10%), in contrast to potent cannabis (>15% THC), which is highly rewarded in the recreational realm. The role of CBD in pain is not clear, however it has gained popularity. Thus, we hypothesize that the potency of medical cannabis that is advertised online is similar to the cannabis advertised for recreational purposes, which would potentially create a misconception towards medical cannabis. The current lack of knowledge surrounding advertised potencies in the legal cannabis market limits the ability to generate clear policies regarding online advertising to protect patients that are willing to use cannabis for their condition. Thus, we evaluated the advertised THC and CBD content of cannabis products offered online in dispensaries in the United States to determine products' suitability to medicinal use and compare the strength of products offered in legal medical and recreational programs. We recorded THC and CBD concentrations for all herb cannabis products provided by dispensary websites and compared them between or within states. Four Western states (CA, CO, NM, WA) and five Northeastern states (ME, MA, NH, RI, VT) were included. A total of 8,505 cannabis products across 653 dispensaries were sampled. Despite the clear differences between medicinal and recreational uses of cannabis, the average THC concentration advertised online in medicinal programs was similar (19.2% ±6.2) to recreational programs (21.5% ±6.0) when compared between states with different programs, or between medicinal and recreational programs within the same states (CO or WA). Lower CBD concentrations accompanied higher THC products. The majority of products, regardless of medicinal or recreational programs, were advertised to have >15% THC (70.3% - 91.4% of products). These stated concentrations seem unsuitable for medicinal purposes, particularly for patients with chronic neuropathic pain. Therefore, this information could induce the misconception that high potency cannabis is safe to treat pain. This data is consistent with reports in which THC and CBD in products from legal dispensaries or in nationwide products from the illegal market were actually measured, which indicates that patients consuming these products may be at risk of acute intoxication or long-term side effects. Our study offers grounds to develop policies that help prevent misconceptions toward cannabis and reduce risks in pain patients.

Driving Under the Influence of Cannabis: A Framework for Future Policy

Marijuana is the most widely consumed illicit substance in the United States, and an increasing number of states have legalized it for both medicinal and recreational purposes. As it becomes more readily available, there will be a concurrent rise in the number of users and, consequently, the number of motor vehicle operators driving under the influence. This article examines the cognitive and psychomotor effects of cannabis, as well as current policy concerning driving under the influence of drugs. The authors performed a MEDLINE search on the epidemiology of cannabis use, its cognitive and psychomotor effects, and policies regarding driving under the influence of drugs. Twenty-eight epidemiological studies, 16 acute cognitive and psychomotor studies, 8 chronic cognitive and psychomotor studies, and pertinent state and federal laws and policies were reviewed. These search results revealed that marijuana use is associated with significant cognitive and psychomotor effects. In addition, the legalization of marijuana varies from state to state, as do the laws pertaining to driving under the influence of drugs. Marijuana is a commonly found illicit substance in motor vehicle operators driving under the influence of drugs. Current evidence shows that blood levels of tetrahydrocannabinol do not correlate well with the level of impairment. In addition, although acute infrequent use of cannabis typically leads to cognitive and psychomotor impairment, this is not consistently the case for chronic heavy use. To establish the framework for driving under the influence of cannabis policy, we must review the current published evidence and examine existing policy at state and federal levels.

Effect of Smoked Cannabis on Vigilance and Accident Risk Using Simulated Driving in Occasional and Chronic Users and the Pharmacokinetic-Pharmacodynamic Relationship

BACKGROUND

The pharmacokinetic-pharmacodynamic relationship between whole blood δ-9-tetrahydrocannabinol (THC) and driving risk is poorly understood.

METHODS

Fifteen chronic cannabis consumers (1-2 joints/day; CC) and 15 occasional cannabis consumers (1-2 joints/week; OC) of 18 to 34 years of age were included. A pharmacokinetic study was conducted with 12 blood samplings over a 24-h period before and after controlled random inhalation of placebo or 10 mg or 30 mg of THC. THC and metabolites were quantified using LC-MS/MS. Effects on reaction time by psychomotor vigilance tests and driving performance through a York driving simulator were evaluated 7 times. A pharmacokinetic-pharmacodynamic analysis was performed using R software.

RESULTS

Whole blood peak THC was 2 times higher in CC than in OC for a same dose and occurred 5 min after the end of consumption. THC remained detectable only in CC after 24 h. Despite standardized consumption, CC consumed more available THC from each cigarette regardless of dose. Maximal effect for reaction time was dose- and group-dependent and only group-dependent for driving performance, both being decreased and more marked in OC than in CC. These effects were maximal around 5 h after administration, and the duration was longer in OC than in CC. A significant pharmacokinetic-pharmacodynamic relationship was observed only between T _max for blood THC and the duration effect on mean reciprocal reaction time.

CONCLUSIONS

Inhalation from cannabis joints leads to a rapid increase in blood THC with a delayed decrease in vigilance and driving performance, more pronounced and lasting longer in OC than in CC. ClinicalTrials.gov Identifier: NCT02061020.

Urinary Kinetics of Heroin Metabolites in Pigs Shortly After Intake

In previous experimental studies on heroin metabolites excretion in urine, the first sample was often collected a few hours after intake. In forensic cases, it is sometimes questioned if a positive urine result is expected e.g., 30 min after intake. The aim of this study was to investigate urinary excretion of heroin metabolites (morphine, 6-monoacetylmorphine (6-MAM) and morphine-3-glucuronide (M3G)) every 30 min until 330 min after injection of a 20 mg heroin dose in six pigs. Samples were analyzed using a previously published, fully validated liquid chromatography-tandem mass spectrometry method. All metabolites were detected after 30 min in all pigs. The time to maximum concentration (Tmax) median (range) for 6-MAM and morphine was 30 min (first sample) (30-120), and 90 min (30-330) for M3G. In four of the six pigs, the Tmax of 6-MAM and morphine was reached within 30 min. All analytes were still detectable at the end of study. This study showed that positive results in urine are expected to be seen shortly after use of heroin in pigs. Detection times were longer than previously indicated, especially for 6-MAM, but previous studies used lower doses. As the physiology of these animals resembles that of the humans, transferability to man is expected.

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.

THC and CBD in blood samples and seizures in Norway: Does CBD affect THC-induced impairment in apprehended subjects?

BACKGROUND AND AIMS

Several publications have suggested increasing cannabis potency over the last decade, which, together with lower amounts of cannabidiol (CBD), could contribute to an increase in adverse effects after cannabis smoking. Naturalistic studies on tetrahydrocannabinol (THC) and CBD in blood samples are, however, missing. This study aimed to investigate the relationship between THC- and CBD concentrations in blood samples among cannabis users, and to compare cannabinoid concentrations with the outcome of a clinical test of impairment (CTI) and between traffic accidents and non-accident driving under the influence of drugs (DUID)-cases. Assessment of THC- and CBD contents in cannabis seizures was also included.

METHODS

THC- and CBD concentrations in blood samples from subjects apprehended in Norway from April 2013-April 2015 were included (n=6134). A CTI result was compared with analytical findings in cases where only THC and/or CBD were detected (n=705). THC- and CBD content was measured in 41 cannabis seizures.

RESULTS

Among THC-positive blood samples, 76% also tested positive for CBD. There was a strong correlation between THC- and CBD concentrations in blood samples (Pearson's r=0.714, p<0.0005). Subjects judged as impaired by a CTI had significantly higher THC- (p<0.001) and CBD (p=0.008) concentrations compared with not impaired subjects, but after multivariate analyses, impairment could only be related to THC concentration (p=0.004). Analyzing seizures revealed THC/CBD ratios of 2:1 for hashish and 200:1 for marijuana.

CONCLUSIONS

More than ¾ of the blood samples testing positive for THC, among subjects apprehended in Norway, also tested positive for CBD, suggesting frequent consumption of high CBD cannabis products. The simultaneous presence of CBD in blood does, however, not appear to affect THC-induced impairment on a CTI. Seizure sample analysis did not reveal high potency cannabis products, and while CBD content appeared high in hashish, it was almost absent in marijuana.

Risk Factors for Driving After and During Marijuana Use

OBJECTIVE

Use of marijuana before or while driving significantly contributes to driving impairment and elevated risk of motor vehicle accidents; however, this risk behavior is common among users. Little is known about the etiology of driving while under the influence of marijuana.

METHOD

Guided by social learning theory, this study examined marijuana outcome expectancies and other driving-related cognitions as predictors of the frequency of driving after smoking marijuana (DASM) and smoking marijuana while driving (SMWD). A community sample of 151 (64% male) non-treatment-seeking frequent marijuana users completed questionnaires on variables of interest.

RESULTS

Perceived driving-related peer norms (i.e., perception that fewer friends disapprove of DASM and SMWD and of riding with a driver under the influence of marijuana) were associated with lower frequency of both DASM and SMWD. Perceived dangerousness of DASM was also associated with decreased frequency of DASM.

CONCLUSIONS

Our findings suggest a range of potentially important targets for interventions intended to reduce the likelihood and frequency of driving while under the influence of marijuana.

The rapidly increasing trend of cannabis use in burn injury

The use of cannabis is currently increasing according to U.S. Department of Health and Human Services (HHS). Surprisingly, cannabis use among burn patients is poorly reported in literature. In this study, rates of cannabis use in burn patients are compared with general population. Data from the National Burn Repository (NBR) were used to investigate incidence, demographics, and outcomes in relation to use of cannabis as evidenced by urine drug screen (UDS). Thousands of patients from the NBR from 2002 to 2011 were included in this retrospective study. Inclusion criteria were patients older than 12 years of age who received a drug screen. Data points analyzed were patients' age, sex, UDS status, mechanism of burn injury, total body surface area, length of stay, ICU days, and insurance characteristics. Incidence of cannabis use in burn patients from the NBR was compared against national general population rates (gathered by Health and Human Services) using chi-square tests. Additionally, the burn patient population was analyzed using bivariate analysis and t-tests to find differences in the characteristics of these patients as well as differences in outcomes. Seventeen thousand eighty out of over 112,000 patients from NBR had information available for UDS. The incidence of cannabis use is increasing among the general population, but the rate is increasing more quickly among patients in the burn patient population (P = .0022). In 2002, 6.0% of patients in burn units had cannabis+ UDS, which was comparable with national incidence of 6.2%. By 2011, 27.0% of burn patients tested cannabis+ while national incidence of cannabis use was 7.0%. Patients who test cannabis+ are generally men (80.1%, P < .0001) and are younger on average (35 years old vs 42, P < .0001). The most common mechanisms of injury among patients who test cannabis+ or cannabis- are similar. Flame injury makes up >60% of injuries, followed by scalds that are >15%. In comparing cannabis+/- patients, cannabis+ patients are more likely to be uninsured (25.2% vs 17.26%, P < .0001). Finally, patients who test cannabis+ have larger burns (TBSA% of 12.94 vs 10.98, P < .0001), have a longer length of stay (13.31 days vs 12.6, P = .16), spend more days in the ICU (7.84 vs 6.39, P = .0006), and have more operations (2.78 vs 2.05, P < .0001). The rate patients testing positive for cannabis in burn units is growing quickly. These patients are younger and are less likely to be insured. These patients also have larger burns, spend more time in ICUs, and have a greater number of operations. The increasing use of cannabis, as expected from legalization of cannabis in multiple states, among burn patient population may lead to increased burden on already tenuous health care resources.

Marijuana's acute effects on cognitive bias for affective and marijuana cues

Marijuana produces acute increases in positive subjective effects and decreased reactivity to negative affective stimuli, though may also acutely induce anxiety. Implicit attentional and evaluative processes may explicate marijuana's ability to acutely increase positive and negative emotions. This within-subjects study examined whether smoked marijuana with 2.7-3.0% delta-9-tetrahydrocannabinol (THC), relative to placebo, acutely changed attentional processing of rewarding and negative affective stimuli as well as marijuana-specific stimuli. On 2 separate days, regular marijuana users (N = 89) smoked placebo or active THC cigarette and completed subjective ratings of mood, intoxication, urge to smoke marijuana, and 2 experimental tasks: pleasantness rating (response latency and perceived pleasantness of affective and marijuana-related stimuli) and emotional Stroop (attentional bias to affective stimuli). On the pleasantness rating task, active marijuana increased response latency to negatively valenced and marijuana-related (vs. neutral) visual stimuli, beyond a general slowing of response. Active marijuana also increased pleasantness ratings of marijuana images, although to a lesser extent than placebo due to reduced marijuana urge after smoking. Overall, active marijuana did not acutely change processing of positive emotional stimuli. There was no evidence of attentional bias to affective word stimuli on the emotional Stroop task with the exception of attentional bias to positive word stimuli in the subgroup of marijuana users with cannabis dependence. Marijuana may increase allocation of attentional resources toward marijuana-specific and negatively valenced visual stimuli without altering processing of positively valenced stimuli. Marijuana-specific cues may be more attractive with higher levels of marijuana craving and less wanted with low craving levels.

Cross-sectional and prospective relation of cannabis potency, dosing and smoking behaviour with cannabis dependence: an ecological study

BACKGROUND AND AIMS

Increased delta-9-tetrahydrocannabinol (THC) concentrations in cannabis may lead to higher THC exposure, cannabis dependence and treatment need, but users may also adapt the actual intake of THC through reduced inhalation of THC containing smoke (titration). We investigated whether consumers of stronger cannabis use less cannabis per joint or inhale less smoke than those using less potent cannabis and whether these factors predict cannabis dependence severity.

METHODS

Heavy cannabis users (n = 98) brought their own cannabis, rolled a joint and smoked it ad libitum in a naturalistic setting. We analysed the content of the joint, its association with smoking behaviour and the cross-sectional and prospective (1.5-year follow-up) relations between smoking behaviour and cannabis dependence severity (total number of DSM-IV dependence symptoms).

RESULTS

THC concentration in cannabis (range 1.10-24.70%) was correlated positively with cannabis dose per joint (b = 0.008, P = 0.01), but the resulting THC concentration per joint (range 0.24-15.72%) was associated negatively with inhalation volume (b = -0.05, P = 0.03). Smoking behaviour measures (number of puffs, inhaled volume, reduction of puff volume and puff duration while smoking) predicted follow-up dependence severity, independently of baseline dependence severity and monthly THC dose (number of joints × cannabis dose × cannabis THC concentration). Monthly THC dose only predicted follow-up dependence severity when unadjusted for baseline severity.

CONCLUSIONS

Cannabis users titrate their delta-9-tetrahydrocannabinol intake by inhaling lower volumes of smoke when smoking strong joints, but this does not fully compensate for the higher cannabis doses per joint when using strong cannabis. Thus, users of more potent cannabis are generally exposed to more delta-9-tetrahydrocannabinol. Smoking behaviour appears to be a stronger predictor for cannabis dependence severity than monthly delta-9-tetrahydrocannabinol dose.

Δ(9)-Tetrahydrocannabinol treatment during human monocyte differentiation reduces macrophage susceptibility to HIV-1 infection

The major psychoactive component of marijuana, Δ(9)-tetrahydrocannabinol (THC), also acts to suppress inflammatory responses. Receptors for THC, CB1, CB2, and GPR55, are differentially expressed on multiple cell types including monocytes and macrophages, which are important modulators of inflammation in vivo and target cells for HIV-1 infection. Use of recreational and medicinal marijuana is increasing, but the consequences of marijuana exposure on HIV-1 infection are unclear. Ex vivo studies were designed to investigate effects on HIV-1 infection in macrophages exposed to THC during or following differentiation. THC treatment of primary human monocytes during differentiation reduced HIV-1 infection of subsequent macrophages by replication competent or single cycle CCR5 using viruses. In contrast, treatment of macrophages with THC immediately prior to or continuously following HIV-1 exposure failed to alter infection. Specific receptor agonists indicated that the THC effect during monocyte differentiation was mediated primarily through CB2. THC reduced the number of p24 positive cells with little to no effect on virus production per infected cell, while quantitation of intracellular viral gag pinpointed the THC effect to an early event in the viral life cycle. Cells treated during differentiation with THC displayed reduced expression of CD14, CD16, and CD163 and donor dependent increases in mRNA expression of selected viral restriction factors, suggesting a fundamental alteration in phenotype. Ultimately, the mechanism of THC suppression of HIV-1 infection was traced to a reduction in cell surface HIV receptor (CD4, CCR5 and CXCR4) expression that diminished entry efficiency.

Prevalence of synthetic cannabinoids in blood samples from Norwegian drivers suspected of impaired driving during a seven weeks period

From early year 2000 different herbal products containing synthetic cannabinoids (SC) have appeared on the drug market all over the world, and new substances are frequently introduced. The prevalence of SC use in different populations is however still mainly unknown, also in Norway. This information is difficult to obtain, but studies of drivers suspected of driving under the influence of drugs (DUID), might provide important information. The aim of this study was to assess the prevalence of SC in drivers suspected of being under the influence of drugs in Norway, and investigate if SCs impair driving performance. For two periods of three and four weeks all blood samples from drivers suspected of DUID in Norway were analyzed for the presence of 12 and 18 different SCs, respectively. A new ultra performance liquid chromatography tandem mass spectrometry method was developed. A total of 726 cases were analyzed during our study period, and SCs were detected in 16 cases (2.2%) in total. The mean age of these drivers was 29.6 years. High concentrations of other psychoactive drugs were detected in all the blood samples where a SC was found. AM-2201 and JWH-018 were the most frequently detected SCs, each found in five cases. In addition RSC-4, JWH-122, JWH-081 and JWH-250 were detected. None of the drivers had reported using SCs prior to driving. Despite the limited number of SCs investigated in this 7 week study period, a considerable percent of the cases were positive. Other psychoactive drugs of abuse were always found concomitant with the SCs, and the age of these drivers indicates that experienced drug users also ingest SCs. Since other drugs were found in all the samples, the psychomotor impairment caused by the SCs is difficult to estimate. Our study shows the importance of screening analyses of biological samples from different populations to assess the prevalence of drug use, since self-reporting might be encumbered with significant under-reporting.