Modulation of the effects of alcohol on driving-related psychomotor skills by chronic exposure to cannabis

Daily diary study of associations between alcohol, cannabis, co-use and sleep quality in individuals with intentions to use cannabis to cope with anxiety

INTRODUCTION

Sleep problems and anxiety conditions are common comorbidities and may be influenced by cannabis and alcohol use. This study examined daily within-person variation in subjective sleep quality among individuals with anxiety symptoms after cannabis or alcohol were used alone, and after co-use.

METHODS

A total of 347 individuals with intentions to use cannabis to cope with anxiety reported their cannabis and alcohol use in the previous 24 h and their previous nights' sleep quality for 30 consecutive days. Mixed-effects models examined whether the within-person daily variation in use of cannabis and alcohol (alone and co-use) was associated with subjective sleep quality. Models also examined whether daily cannabis and alcohol use associations with sleep were moderated by frequency of cannabis, alcohol and co-use during the study period.

RESULTS

Compared to non-use, participants reported better sleep after cannabis-use-only and after co-use, but not after alcohol-use-only. People who more frequently use alcohol and cannabis reported sleeping better after cannabis-use-only days compared to those who use cannabis and alcohol less frequently.

DISCUSSION AND CONCLUSIONS

The study's utilisation of naturalistic data among individuals with anxiety symptoms replicated previously reported experimental findings among individuals without sleep and anxiety problems that overall, cannabis is associated with higher subjective sleep quality. The results expand upon other research to suggest that more frequent use of alcohol and cannabis may moderate daily associations of cannabis use and sleep, potentially through pharmacokinetics and cross-sensitisation.

Driving under the influence of cannabis: A 5-year retrospective Italian study

INTRODUCTION

Cannabis consumption is associated with driving impairment and increased crash risk, endangering road safety. Toxicological analyses play a fundamental role in detecting a recent consumption of psychoactive substances. The aim of this study was to examine the concentration of cannabinoids in blood samples of driving-under-the-influence (DUI) offenders in order to investigate whether delayed sample collection affects the toxicological assessment of the offenders.

MATERIALS AND METHODS

An observational retrospective study was performed using anonymized toxicological data referring to cannabis-related DUI offenders involved in road traffic accidents (RTA) or apprehended by the police from 1 January 2017-31 December 2021 archived at Legal Medicine and Toxicology Department of the University Hospital of Padova, Italy.

RESULTS

In a total sample of 318 drivers, 143 blood samples tested positive for tetrahydrocannabinol (THC) and metabolites 11-hydroxy-Δ9-tetrahydrocannabinol (11-OH-THC) and 11-nor-Δ9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH), and 173 blood samples were positive for THC-COOH with THC negative. In the first group, the mean concentrations of THC and THC-COOH were 4.05 ng/mL and 28.29 ng/mL, respectively. In THC-negative cases, the mean THC-COOH concentration was 7.3 ng/mL. The time elapsed between the event and sample collection varied from 15 min to 7 h (mean 2 h 29 min). The average estimated time elapsed after consumption of cannabinoids was 3 h 7 min (Model I) and 2 h 36 min (Model II).

CONCLUSIONS

The present research discussed the main difficulties in the toxicological evaluation of drivers under the influence of Cannabis. Issues related to the time between RTA and sample collection, the laws and legal limits in force in various Countries were presented.

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.

Differential effects of stimulant versus opiate drugs on driving performance

BACKGROUND AND AIMS

Pharmacological differences among different drug classes influence human cognition, visual, and motor behavior in different ways. These differences impact driving safety, and therefore individuals who use stimulant and opioid drugs might experience different patterns in driving safety and impairment in driving performance. This study examined the effect of long-term use of stimulant drugs and of opiate drugs on driving performance, hazard perception, visual search skills and psychomotor skills related to driving.

METHODS

A total of 75 individuals, including 28 predominantly stimulant users, 22 predominantly opiate users and 25 healthy non-drug users, participated. Driving performance and psychomotor skills were assessed via a 15-minute drive in a simulator; hazard perception was assessed via a computerized task; and visual search skill was assessed by eye tracking.

RESULTS

ANOVA analyses indicate both stimulant and opiate users drove at higher speeds and experienced more crashes than the healthy non-drug users. Stimulant but not opiate users violated red light regulations more often than the healthy non-drug users. In the hazard perception task, stimulant drug users performed more poorly than both opioid drug users and healthy non-drug users. Specifically, they had lower saccade movement scores and higher average fixation times.

CONCLUSIONS

Results confirm that both stimulant drug users and opiate drug users show impaired driving performance compared to healthy non-drug users. Stimulant drug users possessed poorer hazard perception skills compared to the opiate users and the control group, perhaps as a result of cognitive deficits created by the drug use.

Alcohol Use Disorder Symptoms Rather than Alcohol Exposure Predict Experiences of Cannabis Use Disorder Symptoms among Adolescents and Young Adults

Background: Alcohol and cannabis use are highly comorbid. Objective: We evaluate if alcohol use and/or alcohol use disorder symptoms predict experiences of cannabis use disorder symptoms among adolescents and young adults and whether the relationships differ based on frequency of cannabis use, recency of cannabis initiation and age. Method: Data were drawn from five annual surveys of the National Survey on Drug Use and Health (2014-2018) to include adolescents and young adults (age 12 to 21 years) who reported using cannabis and alcohol at least once in the past 30 days. Results: Number of alcohol use disorder symptoms, over and above alcohol quantity or frequency, was positively associated with each of the cannabis use disorder symptoms as well as the total number of cannabis use disorder symptoms endorsed. The association between alcohol and cannabis use disorder symptoms was stronger among those who were younger and those who initiated cannabis use within the past 2 years. Conclusions: Treatment should consider these and other cross-over effects of substance disorder symptoms when addressing risk for chronic and dependent use.

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

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

Cannabis effects on driving lateral control with and without alcohol

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Impact of alcohol on sexual decision making: Intentions to have unprotected sex

The impact of alcohol on intentions to have sex with a new partner and the antecedents of intentions were investigated in three studies (N = 139, 60, and 218, respectively). In all three studies, respondents were intoxicated or not intoxicated with alcohol and completed measures based on the Theory of Planned Behaviour in relation to having sex whilst imagining him- or her-self in the scenario. The scenario described unprotected sex between two individuals not in an existing relationship. Consistently across studies, intoxication had a significant effect on intentions for men but not for women. Also consistently across studies, affective attitudes were significantly stronger determinants of intentions for women than for men. Alcohol intoxication consistently moderated the impact of affective attitudes on intentions in women but not men, with greater intoxication associated with stronger impacts (Studies 1, 2, and 3). Implications for understanding the impacts of alcohol intoxication on sexual decision making in men and women are discussed.

The moderating effect of stimulus attractiveness on the effect of alcohol consumption on attractiveness ratings

AIMS

To explore the enhancing effect of alcohol consumption on attractiveness ratings, in that few studies on the Beer Goggles effect control the stimuli attractiveness level and researchers have seldom considered extending the effect to stimuli other than faces.

METHODS

Male and female participants (n = 103) were randomly assigned to alcohol consumption or placebo groups. Both groups were asked to assess the attractiveness of two types of pictures (faces and landscapes) with three levels of attractiveness for each stimulus category (high, moderate and low).

RESULTS

We found significant interactions between beverage type and attractiveness level. Attractiveness ratings for moderate- and low-attractiveness faces were significantly higher in the alcohol compared with placebo condition, while there was no significant difference for high-attractiveness stimuli between these two conditions. As for landscapes, only low-attractiveness stimuli were rated significantly higher in the alcohol condition.

CONCLUSION

Whether or not alcohol consumption leads to an increase in attractiveness ratings depends on the initial attractiveness of the stimulus materials. Alcohol consumption tends to affect ratings for stimuli with relatively low attractiveness. Furthermore, this effect is not limited to faces; it extends to other types of stimuli like landscapes.

The effects of cannabis and alcohol on simulated driving: Influences of dose and experience

BACKGROUND

Cannabis and alcohol are the most popular drugs amongst recreational users, and most prevalent in injured and deceased drivers. Clarification of the interactive effects of these drugs upon driving behaviour is critical for reducing drug-related road deaths.

OBJECTIVES

The current study had two objectives, to examine the effects of cannabis and alcohol on driving performance, and identify if any differences between the effects of cannabis and alcohol on driving performance exist between regular cannabis users and non-regular cannabis users.

METHODS

The project involved 80 participants (49 male, 31 female) who were abstinent recreational users of alcohol and marijuana. They participated in six experimental sessions that involved the consumption of cannabis cigarettes containing no THC, 1.8% THC or 3% THC together with the consumption of alcohol to obtain either 0% BAC, 0.03% BAC or 0.05% BAC. The six sessions were double-blind, counter-balanced, placebo-controlled and medically supervised. Forty participants were allocated to the cannabis with low alcohol (0.03% BAC) group, and 40 participants were allocated to the cannabis with high alcohol (0.05% BAC) group. Driving simulator performance was assessed at 20min post-drug administration and blood samples were taken before and after driving.

RESULTS

Driving simulator performance was more impaired in the THC and alcohol combined conditions. Consistent with past research, the level of THC detected in blood is higher when THC is consumed with alcohol, than when cannabis is consumed alone, and regular cannabis users returned higher levels of THC in plasma than non-regular users. Generally, regular cannabis users displayed more driving errors than non-regular cannabis users.

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

INTRODUCTION

Previous research has shown that heavy cannabis users develop tolerance to the impairing effects of Δ9-tetrahydrocannabinol (THC) on neurocognitive functions. Animal studies suggest that chronic cannabis consumption may also produce cross-tolerance for the impairing effects of alcohol, but supportive data in humans is scarce.

PURPOSE

The present study was designed to assess tolerance and cross-tolerance to the neurocognitive effects of THC and alcohol in heavy cannabis users.

METHODS

Twenty-one heavy cannabis users participated in a double-blind, placebo-controlled, three-way study. Subjects underwent three alcohol-dosing conditions that were designed to achieve a steady blood alcohol concentration of about 0, 0.5, and 0.7 mg/ml during a 5-h time window. In addition, subjects smoked a THC cigarette (400 μg/kg) at 3 h post-onset of alcohol dosing during every alcohol condition. Performance tests were conducted repeatedly between 0 and 7 h after onset of drinking and included measures of perceptual motor control (critical tracking task), dual task processing (divided-attention task), motor inhibition (stop-signal task), and cognition (Tower of London).

RESULTS

Alcohol significantly impaired critical tracking, divided attention, and stop-signal performance. THC generally did not affect task performance. However, combined effects of THC and alcohol on divided attention were bigger than those by alcohol alone.

CONCLUSION

In conclusion, the present study generally confirms that heavy cannabis users develop tolerance to the impairing effects of THC on neurocognitive task performance. Yet, heavy cannabis users did not develop cross-tolerance to the impairing effects of alcohol, and the presence of the latter even selectively potentiated THC effects on measures of divided attention.

The effect of cannabis compared with alcohol on driving

The prevalence of both alcohol and cannabis use and the high morbidity associated with motor vehicle crashes has lead to a plethora of research on the link between the two. Drunk drivers are involved in 25% of motor vehicle fatalities, and many accidents involve drivers who test positive for cannabis. Cannabis and alcohol acutely impair several driving-related skills in a dose-related fashion, but the effects of cannabis vary more between individuals than they do with alcohol because of tolerance, differences in smoking technique, and different absorptions of Delta(9)-tetrahydrocannabinol (THC), the active ingredient in marijuana. Detrimental effects of cannabis use vary in a dose-related fashion, and are more pronounced with highly automatic driving functions than with more complex tasks that require conscious control, whereas alcohol produces an opposite pattern of impairment. Because of both this and an increased awareness that they are impaired, marijuana smokers tend to compensate effectively while driving by utilizing a variety of behavioral strategies. Combining marijuana with alcohol eliminates the ability to use such strategies effectively, however, and results in impairment even at doses which would be insignificant were they of either drug alone. Epidemiological studies have been inconclusive regarding whether cannabis use causes an increased risk of accidents; in contrast, unanimity exists that alcohol use increases crash risk. Furthermore, the risk from driving under the influence of both alcohol and cannabis is greater than the risk of driving under the influence of either alone. Future research should focus on resolving contradictions posed by previous studies, and patients who smoke cannabis should be counseled to wait several hours before driving, and avoid combining the two drugs.

Dissociations between motor timing, motor coordination, and time perception after the administration of alcohol or caffeine

RATIONALE

The impacts of psychoactive drugs on timing have usefully informed theories of timing and its substrates.

OBJECTIVES

The objectives of the study are to test the effects of alcohol and caffeine on the explicit timing involved in tapping with the implicit timing observed in the coordinated picking up of an object, and with the temporal discrimination.

MATERIALS AND METHODS

Participants in the "alcohol" experiment (N = 16) received placebo, "low" (0.12 g/kg or 0.14 g/kg for women/men, respectively) or "high" (0.37 g/kg or 0.42 g/kg, respectively) doses of alcohol, and those in the "caffeine" experiment (N = 16) received placebo, 200 or 400 mg caffeine. Time production variability was measured by repetitive tapping of specified intervals, and sources of variance attributable to central timer processes and peripheral motor implementation were dissociated. The explicit timing in tapping was compared with the implicit timing in the coordinated picking up of an object. Time perception was measured as discrimination thresholds for intervals of similar duration. Drug effects on reaction time were also measured.

RESULTS

For tapping, alcohol significantly increased timer variability, but not motor variability; it did not affect coordination timing in the grip-lift task. Conversely, for time perception, the low dose of alcohol improved temporal discrimination. Caffeine produced no effects on any of the timing tasks, despite significantly reducing reaction times.

CONCLUSIONS

The effects of alcohol argue against a common clock process underlying time interval perception and production in the range below 1 s. In contrast to reaction time measures, time perception and time production appear relatively insensitive to caffeine.

Driving under the influence of cannabis: a 10-year study of age and gender differences in the concentrations of tetrahydrocannabinol in blood

BACKGROUND

Delta(9)-Tetrahydrocannabinol (THC) is the major psychoactive constituent of cannabis and its various preparations. Increasing use of cannabis for recreational purposes has created a problem for road-traffic safety. This paper compares age, gender and the concentrations of THC in blood of individuals apprehended for driving under the influence of drugs (DUID) in Sweden, where a zero-tolerance law operates.

MEASUREMENTS

Specimens of blood or urine were subjected to a broad screening analysis by enzyme immunoassay methods. THC positives were verified by analysis of blood by gas chromatography-mass spectrometry (GC-MS) with a deuterium-labelled internal standard (d(3)-THC). All toxicology results were entered into a database (TOXBASE) along with the age and gender of apprehended drivers.

FINDINGS

Over a 10-year period (1995-2004), between 18% and 30% of all DUID suspects had measurable amounts of THC in their blood (> 0.3 ng/ml) either alone or together with other drugs. The mean age [+/- standard deviation (SD)] of cannabis users was 33 +/- 9.4 years (range 15-66 years), with a strong predominance of men (94%, P < 0.001). The frequency distribution of THC concentrations (n = 8794) was skewed markedly to the right with mean, median and highest values of 2.1 ng/ml, 1.0 ng/ml and 67 ng/ml, respectively. The THC concentration was less than 1.0 ng/ml in 43% of cases and below 2.0 ng/ml in 61% of cases. The age of offenders was not correlated with the concentration of THC in blood (r = -0.027, P > 0.05). THC concentrations in blood were higher when this was the only psychoactive substance present (n = 1276); mean 3.6 ng/ml, median 2.0 ng/ml compared with multi-drug users; mean 1.8 ng/ml, median 1.0 ng/ml (P < 0.001). In cases with THC as the only drug present the concentration was less than 1.0 ng/ml in 26% and below 2.0 ng/ml in 41% of cases. The high prevalence of men, the average age and the concentrations of THC in blood were similar in users of illicit drugs (non-traffic cases).

CONCLUSIONS

The concentration of THC in blood at the time of driving is probably a great deal higher than at the time of sampling (30-90 minutes later). The notion of enacting science-based concentration limits of THC in blood (e.g. 3-5 ng/ml), as discussed in some quarters, would result in many individuals evading prosecution. Zero-tolerance or limit of quantitation laws are a much more pragmatic way to enforce DUID legislation.

The Toxicology of Cannabis and Cannabis Prohibition

The acute side effects caused by cannabis use are mainly related to psyche and cognition, and to circulation. Euphoria, anxiety, changes in sensory perception, impairment of memory and psychomotor performance are common effects after a dose is taken that exceeds an individually variable threshold. Cannabis consumption may increase heart rate and change blood pressure, which may have serious consequences in people with heart disease. Effects of chronic use may be induction of psychosis and development of dependency to the drug. Effects on cognitive abilities seem to be reversible after abstinence, except possibly in very heavy users. Cannabis exposure in utero may have negative consequences on brain development with subtle impairment of cognitive abilities in later life. Consequences of cannabis smoking may be similar to those of tobacco smoking and should be avoided. Use by young people has more detrimental effects than use by adults. There appear to be promising therapeutic uses of cannabis for a range of indications. Use of moderate doses in a therapeutic context is usually not associated with severe side effects. Current prohibition on cannabis use may also have harmful side effects for the individual and the society, while having little influence on prevalence of use. Harm is greatest for seriously ill people who may benefit from a treatment with cannabis. This makes it difficult to justify criminal penalties against patients.

Involvement of the endogenous cannabinoid system in the effects of alcohol in the mesolimbic reward circuit: electrophysiological evidence in vivo

RATIONALE

Several lines of evidence indicate that the endogenous cannabinoid system is involved in the pharmacological and behavioural effects of alcohol. The mesolimbic dopaminergic (DA) system and the nucleus accumbens (NAc) process rewarding properties of drugs of abuse, including alcohol and cannabinoids, whereas endocannabinoids in these regions modulate synaptic function and mediate short- and long-term forms of synaptic plasticity.

OBJECTIVES

The present study was designed to investigate the contribution of the endogenous cannabinoid system in alcohol electrophysiological effects in the mesolimbic reward circuit.

METHODS

We utilized extracellular single cell recordings from ventral tegmental area (VTA) DA and NAc neurons in anesthetized rats. DA neurons were antidromically identified as projecting to the shell of NAc, whereas NAc putative medium spiny neurons were identified by their evoked responses to basolateral amygdala (BLA) stimulation.

RESULTS

Alcohol stimulated firing rate of VTA DA neurons and inhibited BLA-evoked NAc neuron spiking responses. The cannabinoid type-1 receptor (CB1) antagonist rimonabant (SR141716A) fully antagonized alcohol effect in both regions. In the NAc, either inhibition of the major catabolic enzyme of the endocannabinoid anandamide, the fatty-acid amyd hydrolase, with URB597 or a pretreatment with the CB1 receptor agonist WIN55212-2 significantly depressed alcohol-induced effects in the NAc.

CONCLUSIONS

These results corroborate the notion of the involvement of endocannabinoids and their receptors in the actions of alcohol and highlight the endocannabinoid system as a valuable target in the therapy for alcoholism.

Driving while impaired (DWI) by alcohol convictions among alcohol, cocaine, and cannabis clients in treatment

OBJECTIVE

Although studies have demonstrated that clients in treatment for alcohol abuse are more at risk of driving while impaired (DWI) by alcohol than normal licensed drivers from the general population, no research was found on DWI convictions among those in treatment for abusing cannabis or cocaine. The purpose of this article is to compare DWI convictions among clients in treatment for alcohol, cannabis, cocaine, or various combinations of these substances, compared to a matched population control group.

METHOD

A stratified random sample of driver records was drawn from seven client groups who sought treatment in 1994 for alcohol, cannabis, cocaine, or any combination of these substances (n = 445). A random sample of drivers, frequency matched by age and sex (n = 566), served as control subjects.

RESULTS

Logistic regression analysis, controlling for sex and age, was conducted to assess whether DWI convictions were elevated for each of the client groups, compared to controls. Two sets of analyses were conducted, before treatment (from 1985 to 1993) and after treatment (from 1995 to 2000). In the time period before treatment, every drug group except the "cannabis only" group had significantly more DWI convictions than controls (p < .05). In the period after treatment, the "alcohol only," "cocaine only," "alcohol and cocaine," and the "cocaine and cannabis" groups still had significantly more DWI convictions than controls (p < .05).

CONCLUSION

The results show that DWI convictions are elevated among those who abused cocaine but not among those who abused cannabis. The results suggest that cross-addiction of alcohol and cocaine is common, and problematic drinking among cocaine clients can go undetected when clients are being diagnosed for treatment.

The safety of cannabinoids for the treatment of multiple sclerosis

The evidence for the therapeutic efficacy of cannabinoids in the treatment of multiple sclerosis (MS) is increasing but is not as yet convincing. Although several trials have reported no significant effect, the majority of the evidence which supports a beneficial effect on spasticity and pain is based on subjective measurements in trials where unblinding was likely to be a problem. The available clinical trial data suggest that the adverse side effects associated with using cannabis-based medicinal extracts (CBMEs) are generally mild, such as dry mouth, dizziness, somnolence, nausea and intoxication, and in no case did toxicity develop. However, most of these trials were run over a period of months and it is possible that other adverse side effects, not seen in these short-term studies, could develop with long-term use. Despite the evidence that cannabinoids can disrupt cognitive function and promote depression, on the basis of current data, such adverse effects seem unlikely to be associated with the use of CBMEs. Likewise, there is no evidence to suggest that their effects on balance and motor control, or immune function, may be clinically significant. There is, however, reason to be concerned about the use of therapeutic cannabinoids by people predisposed to psychosis and by pregnant women, given the increasing evidence of their adverse effects on the fetus. In conclusion, given the modest therapeutic effects of cannabinoids demonstrated so far, and the risk of long-term adverse side effects, there is reason to be cautious about their use in the treatment of MS.

Adverse effects of cannabis on health: an update of the literature since 1996

Recent research has clarified a number of important questions concerning adverse effects of cannabis on health. A causal role of acute cannabis intoxication in motor vehicle and other accidents has now been shown by the presence of measurable levels of Delta(9)-tetrahydrocannabinol (THC) in the blood of injured drivers in the absence of alcohol or other drugs, by surveys of driving under the influence of cannabis, and by significantly higher accident culpability risk of drivers using cannabis. Chronic inflammatory and precancerous changes in the airways have been demonstrated in cannabis smokers, and the most recent case-control study shows an increased risk of airways cancer that is proportional to the amount of cannabis use. Several different studies indicate that the epidemiological link between cannabis use and schizophrenia probably represents a causal role of cannabis in precipitating the onset or relapse of schizophrenia. A weaker but significant link between cannabis and depression has been found in various cohort studies, but the nature of the link is not yet clear. A large body of evidence now demonstrates that cannabis dependence, both behavioral and physical, does occur in about 7-10% of regular users, and that early onset of use, and especially of weekly or daily use, is a strong predictor of future dependence. Cognitive impairments of various types are readily demonstrable during acute cannabis intoxication, but there is no suitable evidence yet available to permit a decision as to whether long-lasting or permanent functional losses can result from chronic heavy use in adults. However, a small but growing body of evidence indicates subtle but apparently permanent effects on memory, information processing, and executive functions, in the offspring of women who used cannabis during pregnancy. In total, the evidence indicates that regular heavy use of cannabis carries significant risks for the individual user and for the health care system.