Improving the quality of the cannabis debate: defining the different domains

Cannabis Prevalence and National Drug Policy in 27 Countries: An Analysis of Adolescent Substance Use

Prior research that assesses the relationship between cannabis policy and prevalence rates has yielded mixed results, perhaps due to the varying rigor of these investigations. Addressing some of these issues in rigor and informed by a rational choice theory (RCT), we hypothesize that those policies on the more punitive end of McDonald and colleagues' classification will be most effective. Examining legislation in 27 countries utilizing the Second International Self-Report Delinquency Study (ISRD-2) through hierarchical linear modeling (HLM) models with both individual- and country-level controls, we find little support for these hypotheses. Instead, results from our analysis largely indicate that the variation in country prevalence rates from 2005 to 2007 was not significantly related to cannabis control policy. We comment on possible policy implications for these preliminary results.

The Cardiovascular Effects of Marijuana: Are the Potential Adverse Effects Worth the High?

Marijuana is the most commonly abused illicit drug in the United States (US) and much of the Westernized World with a steadily increasing prevalence in usage and abuse over the past decade, especially among adolescents. Much of the available data on 9-tetrahydrocannabinol (THC), the main psychoactive ingredient in marijuana, relates to its neurological effects and anti-emetic properties, with very little on the cardiovascular (CV) effects of THC. Available literature shows that THC has three major effects on the CV and the peripheral vasculature in the form of "cannabis arteritis," cannabis-induced vasospasms, and platelet aggregation, with an unknown verdict on the relationship between marijuana use and atherosclerosis progression. This manuscript reviews these effects and possible mechanisms of action. Moreover, limitations on current views of marijuana and indirect causes of CV toxicity will be investigated, such as concurrent drug use, lifestyle, and mental health. The effects of marijuana on the CV system are extremely worrisome and likely need more attention due to the growing legalization of cannabis for medicinal and recreational use across the US. As a result, awareness among health care professionals about potential side effects and toxicities associated with acute and chronic exposure of cannabis will increase in importance.

Time to acknowledge the mixed effects of cannabis on health: a summary and critical review of the NASEM 2017 report on the health effects of cannabis and cannabinoids

This is a summary and critical review of The National Academies of Sciences, Engineering and Medicine (NASEM) report of cannabis’ health effects. The report stated that effects of cannabis are understudied and research findings are mixed. It concluded that the under developed evidence base poses a public health risk and rightly addressed complications of cannabis research that need to be collaboratively resolved. We support NASEM’s urgent call for research, but add that the mixed evidence base cannot be solely attributed to research limitations. Rather, we propose a need to acknowledge the heterogeneity in cannabis’ effects to advance the field.

Cannabis use and psychosis: the origins and implications of an association

Evidence for the effectiveness of treatment or secondary prevention of psychotic illness such as schizophrenia is often disappointing. This situation reflects our limited understanding of the aetiology of psychosis. There is good evidence that both genetic and environmental factors are implicated but the precise identity of these is unclear. Cannabis use is one candidate as a possible, modifiable environmental influence on both incidence and prognosis of psychosis. Evidence supporting this candidature is exclusively observational, and its strength has perhaps been overestimated and problems related to its interpretation underestimated by some. Nevertheless the possibility that cannabis does cause psychosis remains. Because of this, and because there are other good public health reasons to prevent cannabis use, interventions targeting use need to be evaluated. This evaluation, along with other imaginative approaches to future research, is needed to further our understanding of the determinants of mental illness and how we can most effectively improve the population's mental health.

Cannabis Use in Adolescence and Young Adulthood: A Review of Findings from the Victorian Adolescent Health Cohort Study

The Victorian Adolescent Health Cohort Study (VAHCS) is a long-term Australian cohort study that has documented cannabis use in young Australians from the mid-teens to the mid-30s. The study findings have described the natural history of early cannabis use, remission, and escalation and the social and mental health consequences of different patterns of use. The adverse consequences of cannabis use are most clear-cut in heavy early adolescent users. These consequences include educational failure, persisting mental health problems, and progression to other substance use. For later onset and occasional users, the risks are lower and appear to entail modest elevations in risk for other drug use compared with never users. With growing evidence of health consequences, there is a strong case for actions around early heavy adolescent users. Prevention of early use, identification and treatment of early heavy users, and harm reduction through diversion of early heavy users away from the custodial justice system into health care are all priority responses.

Prevalence of cannabis residues in psychiatric patients: a case study of two mental health referral hospitals in Uganda

Various studies have reported that abuse of cannabis is a risk factor for psychosis. The aims of this study were to determine the prevalence of delta 9-tetrahydrocanabinol (Δ(9)-THC), a major metabolite of cannabis, in psychiatric patients in Uganda, and to assess the diagnostic capacity of two referral mental health hospitals to screen patients for exposure to cannabis in Uganda. Socio-demographic characteristics of the patients were collected through questionnaires and review of medical records. Urine samples were collected from 100 patients and analyzed using Δ(9)-THC immunochromatographic kit (Standard Diagnostics(®), South Korea). Seventeen percent of the patients tested positive for Δ(9)-THC residues in their urine. There was strong association (P < 0.05) between history of previous abuse of cannabis and presence of Δ(9)-THC residues in the urine. Alcohol, cocaine, heroin, pethidine, tobacco, khat and kuber were the other substances abused in various combinations. Both referral hospitals lacked laboratory diagnostic kits for detection of cannabis in psychiatric patients. In conclusion, previous abuse of cannabis is associated with occurrence of the residues in psychiatric patients, yet referral mental health facilities in Uganda do not have the appropriate diagnostic kits for detection of cannabis residues as a basis for evidence-based psychotherapy.

Cannabis use in Canada: the need for a 'public health' approach

Cannabis is the most commonly used illicit drug in Canada, used by 1 in 7 adults and 1 in 4 students. Other forms of drug use (e.g., alcohol or injection drug use) are increasingly approached within a public health policy framework that focuses on reducing harms rather than use per se. Cannabis, by contrast, remains formally controlled by a criminal justice approach that focuses on enforcing abstinence. Its use is associated with a variety of possible acute or chronic health problems that include cognitive and respiratory impairment, psychotic episodes, dependence and injury risk. The incidence of these outcomes, however, is predicted by early onset and a high frequency and length of use that only apply to a minority of users. In a public health framework, cannabis use - especially in young populations - should be systematically monitored and high-risk patterns of use screened for in appropriate settings, e.g., schools and GP offices. Evidence-based primary and secondary prevention, treatment and enforcement need to be targeted at these high-risk patterns of use. Given the large cannabis user population, especially among young people, and the failure of the criminalization approach to discourage use, a public health framework for cannabis use is urgently needed in Canada.

Typologies of cannabis users and associated characteristics relevant for public health: a latent class analysis of data from a nationally representative Canadian adult survey

Cannabis is the most prevalently used illicit drug in Canada. Current policy consists primarily of universal use prohibition rather than interventions targeting specific risks and harms relevant for public health. This study aimed to identify distinct groups of cannabis users based on defined use characteristics in the Canadian population, and examine the emerging groups' associations with differential risk and harm outcomes. One thousand three hundred and three current (i.e. use in the past three months) cannabis users, based on data from the representative cross-sectional 2004 Canadian Addiction Survey (N = 13,909), were statistically assessed by a 'latent class analysis' (LCA). Emerging classes were examined for differential associations with socio-demographic, health and behavioral indicators on the basis of chi-square and analysis of variance techniques. Four distinct classes based on use patterns were identified. The class featuring earliest onset and highest frequency of use [22% of cannabis user sample or 2.2% (95% confidence interval (CI) = 1.8-2.7%) of the Canadian adult population] was disproportionately linked to key harms, including other illicit drug use, health problems, cannabis use and driving, and cannabis use problems. A public health framework for cannabis use is needed in Canada, meaningfully targeting effective interventions towards the minority of users experiencing elevated levels of risks and harms.

Age of onset of cannabis use is associated with age of onset of high-risk symptoms for psychosis

OBJECTIVE

Increasing interest in the prodromal stage of schizophrenia over the past decade led us to perform our study to monitor people at high risk for developing a psychosis. We hypothesized that cannabis use or a cannabis use disorder at a younger age relates to high-risk symptoms at a younger age.

METHOD

People referred to the Academic Medical Centre in Amsterdam, the Netherlands, with an ultra-high risk (UHR) for psychosis were interviewed with the Composite International Diagnostic Interview to assess their cannabis consumption. The Interview for the Retrospective Assessment of the Onset of Schizophrenia was used to collect data about age of onset of high-risk or prodromal symptoms. Nine high-risk symptoms were selected and clustered because of their known relation with cannabis use.

RESULTS

Among the 68 included participants, 35 had used cannabis (51.5%), of whom 15 had used recently. Twenty-two participants had been cannabis abusers or cannabis-dependent (32.4%) in the past. Younger age at onset of cannabis use was related to younger age of onset of the cluster of symptoms (rho = 0.48, P = 0.003) and also to 6 symptoms individually (rho = 0.47 to 0.90, P < 0.001 to 0.04). Younger age at onset of a cannabis use disorder was related to younger age of onset of the cluster of symptoms (rho = 0.67, P = 0.001) and also to 6 symptoms individually (rho = 0.50 to 0.93, P = 0.007 to 0.03).

CONCLUSION

Cannabis use or a cannabis use disorder at a younger age in a group with an UHR for transition to psychosis is related to onset of high-risk symptoms for psychosis at a younger age.

Evaluation of the DNA damaging potential of cannabis cigarette smoke by the determination of acetaldehyde derived N2-ethyl-2'-deoxyguanosine adducts

Acetaldehyde is an ubiquitous genotoxic compound that has been classified as a possible carcinogen to humans. It can react with DNA to form primarily a Schiff base N(2)-ethylidene-2'-deoxyguanosine (N(2)-ethylidene-dG) adduct. An online column-switching valve liquid chromatography tandem mass spectrometry (LC-MS/MS) selected reaction monitoring (SRM) method was developed for the determination of N(2)-ethylidene-dG adducts in DNA following reduction with sodium cyanoborohydride (NaBH(3)CN) to the chemically stable N(2)-ethyl-2'-deoxyguanosine (N(2)-ethyl-dG) adduct. Accurate quantitation of the adduct was obtained by the addition of the [(15)N(5)]N(2)-ethyl-dG stable isotope-labeled internal standard prior to enzymatic hydrolysis of the DNA samples to 2'-deoxynucleosides with the incorporation of NaBH(3)CN in the DNA hydrolysis buffer. The method required 50 microg of hydrolyzed DNA on column for the analysis, and the limit of detection for N(2)-ethyl-dG was 2.0 fmol. The analysis of calf thymus DNA treated in vitro with acetaldehyde (ranging from 0.5 to 100 mM) or with the smoke generated from 1, 5, and 10 cannabis cigarettes showed linear dose-dependent increases in the level of N(2)-ethyl-dG adducts (r = 0.954 and r = 0.999, respectively). Similar levels (332.8 +/- 21.9 vs 348.4 +/- 19.1 adducts per 10(8) 2'-deoxynucleosides) of N(2)-ethyl-dG adducts were detected following the exposure of calf thymus DNA to 10 tobacco or 10 cannabis cigarettes. No significant difference was found in the levels of N(2)-ethyl-dG adducts in human lung DNA obtained from nonsmokers (n = 4) and smokers (n = 4) with the average level observed as 13.3 +/- 0.7 adducts per 10(8) 2'-deoxynucleosides. No N(2)-ethyl-dG adducts were detected in any of the DNA samples following analysis with the omission of NaBH(3)CN from the DNA hydrolysis buffer. In conclusion, these results provide evidence for the DNA damaging potential of cannabis smoke, implying that the consumption of cannabis cigarettes may be detrimental to human health with the possibility to initiate cancer development.

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.

Hospital separations for cannabis- and methamphetamine-related psychotic episodes in Australia

OBJECTIVE

To examine trends in hospital separations related to "drug-induced" psychosis for cannabis and methamphetamine, in the context of patterns of cannabis and methamphetamine use in the Australian population.

DESIGN AND SETTING

Analysis of prospectively collected data from the National Hospital Morbidity Database on hospital separations primarily attributed to drug-induced psychosis (July 1993 - June 2004), and specifically for cannabis and amphetamines (1999-2004). Calculation of Australian population-adjusted rates of drug-induced psychosis hospital separations using estimated resident population data from the Australian Bureau of Statistics (at 30 June each year) and data on cannabis and methamphetamine use from the 2004 National Drug Strategy Household Survey.

MAIN OUTCOME MEASURES

Number of hospital separations due to drug-induced psychosis, and standardised (age-specific) rates per million population and per million users.

RESULTS

There have been notable increases in hospital separations due to drug-induced psychosis, which appear to have been driven by amphetamine-related rather than cannabis-related episodes. The rate of hospital separations was higher for amphetamine users than for cannabis users in all age groups, and the rate increased among older amphetamine users.

CONCLUSIONS

The risk of hospitalisation for a drug-induced psychotic episode associated with amphetamine use appears to be greater than that for cannabis use in all age groups.

The impact of cannabis on driving

BACKGROUND

Cannabis is known to have detrimental effects on human performance and may also affect driving adversely. However, studies designed to examine this issue have provided equivocal findings. We set up this study to further determine the effect of cannabis on driving.

METHODS

We used a cross-sectional, case-control design with drivers aged 20-49 who were involved in a fatal crash in the United States from 1993 to 2003; drivers were included if they had been tested for the presence of cannabis and had a confirmed blood alcohol concentration of zero. Cases were drivers who had at least one potentially unsafe driving action recorded in relation to the crash (e.g., speeding); controls were drivers who had no such driving action recorded. We calculated the crude and adjusted odds ratios (ORs) of any potentially unsafe driving action in drivers who tested positive for cannabis but negative for alcohol consumption. In computing for the adjusted OR, we controlled for age, sex, and prior driving record.

RESULTS

Five percent of drivers tested positive for cannabis. The crude OR of a potentially unsafe action was 1.39 (99% CI = 1.21-1.59) for drivers who tested positive for cannabis. Even after controlling for age, sex, and prior driving record, the presence of cannabis remained associated with a higher risk of a potentially unsafe driving action (1.29, 99% CI = 1.11-1.50).

CONCLUSION

Cannabis had a negative effect on driving, as would be predicted from human performance studies. This finding supports the need for interventions to decrease the prevalence of driving under the influence of cannabis, and indicates that further studies should be conducted to investigate the dose-response relationship between cannabis and safe driving.

The impact of cannabis on driving

BACKGROUND

Cannabis is known to have detrimental effects on human performance and may also affect driving adversely. However, studies designed to examine this issue have provided equivocal findings. We set up this study to further determine the effect of cannabis on driving.

METHODS

We used a cross-sectional, case-control design with drivers aged 20-49 who were involved in a fatal crash in the United States from 1993 to 2003; drivers were included if they had been tested for the presence of cannabis and had a confirmed blood alcohol concentration of zero. Cases were drivers who had at least one potentially unsafe driving action recorded in relation to the crash (e.g., speeding); controls were drivers who had no such driving action recorded. We calculated the crude and adjusted odds ratios (ORs) of any potentially unsafe driving action in drivers who tested positive for cannabis but negative for alcohol consumption. In computing for the adjusted OR, we controlled for age, sex, and prior driving record.

RESULTS

Five percent of drivers tested positive for cannabis. The crude OR of a potentially unsafe action was 1.39 (99% CI = 1.21-1.59) for drivers who tested positive for cannabis. Even after controlling for age, sex, and prior driving record, the presence of cannabis remained associated with a higher risk of a potentially unsafe driving action (1.29, 99% CI = 1.11-1.50).

CONCLUSION

Cannabis had a negative effect on driving, as would be predicted from human performance studies. This finding supports the need for interventions to decrease the prevalence of driving under the influence of cannabis, and indicates that further studies should be conducted to investigate the dose-response relationship between cannabis and safe driving.

Behavioral effects in adult rats of chronic prepubertal treatment with the cannabinoid receptor agonist WIN 55,212-2

Human and animal studies provide evidence for vulnerable periods of brain development for deleterious effects of cannabinoids. We have recently shown that pubertal chronic cannabinoid treatment leads to long-lasting behavioral deficits, whereas a comparable treatment in adult rats did not affect the animals' behavior. In the present study we examined the effects of an identical chronic cannabinoid treatment in juvenile rats, just before the onset of puberty. Treatment with the synthetic cannabinoid agonist WIN 55,212-2 (WIN) (1.2 mg/kg) or vehicle was extended over 25 days throughout the prepubertal period (postnatal days 15-40) in juvenile rats. The rats received a total of 20 injections intraperitoneally. Adult rats were tested for object recognition memory, performance in a progressive ratio (PR) operant behavior task, locomotor activity and prepulse inhibition (PPI) of the acoustic startle response. Juvenile chronic WIN administration had no effect on object recognition memory, PR performance and locomotor activity in adulthood. However, a PPI deficit was observed in WIN-treated rats when tested as adults that could be reversed by the acute administration of the dopamine receptor antagonist haloperidol (0.1 mg/kg). Additionally, juvenile cannabinoid treatment reduced the number of rearings, as well as the time spent in the center of the open field in adult rats, suggesting increased anxiety. Juvenile chronic cannabinoid treatment induced behavioral disturbances in adult rats that are less severe than those observed after pubertal cannabinoid administration. However, based on the observations of sensorimotor gating deficits and increased anxiety, we conclude that the prepubertal developmental phase, in addition to puberty, also represents a vulnerable time period for persistent adverse effects of cannabinoids.

Motor vehicle collision risk and driving under the influence of cannabis: evidence from adolescents in Atlantic Canada

OBJECTIVE

Employing a sample of 6087 senior students in Atlantic Canada, this paper examines the relationship between driving under the influence of cannabis (DUIC) and motor vehicle collision (MVC) risk. A series of models were analyzed adjusting for demographic characteristics, driver experience, and substance use.

METHODS

Participants were drawn from the 2002/2003 Student Drug Use Survey in the Atlantic Provinces, an anonymous cross-sectional survey of adolescent students in the Atlantic provinces of Canada. Logistic regression techniques were employed in the analysis of unadjusted and adjusted models.

RESULTS

Among senior students, the prevalence of DUIC in the past year was 15.1% while the prevalence of MVCs was 8.1%. The predictors of DUIC were gender, driver experience, use of a fake ID, and driving under the influence of alcohol (DUIA). The predictors of MVC were gender, driver experience, DUIC, and DUIA.

CONCLUSIONS

These findings extend our knowledge of DUIC as a socio-legal and public health issue with implications on road safety. Effort must be placed on educating new drivers about cannabis use in the context of driving.

Reverse gateways? Frequent cannabis use as a predictor of tobacco initiation and nicotine dependence

AIMS

To examine the risk posed by cannabis use in young people for tobacco use disorders. Specifically we examined whether cannabis use in non-smokers predicted later initiation of tobacco use and whether cannabis use predicted later nicotine dependence in tobacco users.

DESIGN

A 10-year eight-wave cohort study.

SETTING

State of Victoria, Australia.

PARTICIPANTS

A community sample of 1943 participants initially aged 14-15 years.

MEASUREMENTS

Self-report of tobacco and cannabis use was assessed in the teens using a computerized interview assessment and in young adulthood with a CATI assessment. The Fagerström Test for Nicotine Dependence was used to define nicotine dependence.

FINDINGS

For teen non-smokers, at least one report of weekly cannabis use in the teens predicted a more than eightfold increase in the odds of later initiation of tobacco use (OR 8.3; 95% CI 1.9-36). For 21-year-old smokers, not yet nicotine-dependent, daily cannabis use raised the odds of nicotine dependence at the age of 24 years more than threefold (OR 3.6, 1.2, 10) after controlling for possible confounders, including level of tobacco use and subsyndromal signs of nicotine dependence.

CONCLUSIONS

Weekly or more cannabis use during the teens and young adulthood is associated with an increased risk of late initiation of tobacco use and progression to nicotine dependence. If this effect is causal, it may be that a heightened risk of nicotine dependence is the most important health consequence of early frequent cannabis use.

Swiss adolescents' and adults' perceptions of cannabis use: a qualitative study

Few studies have attempted to investigate the nature of adolescents' and adults' conceptions and perceptions of cannabis use. Our objectives were to explore adolescent and adult perception of use and misuse of cannabis, and their opinions and beliefs about the current legal context and preventive strategies. We used focus group discussions with four categories of stakeholders: younger (12-15 year old) adolescents, older (16-19 year old) adolescents, parents of teenagers and professionals working with young people. In some areas (legal framework, role of the media, importance of early preventive interventions), we found consensual attitudes and beliefs across the four groups of participants. In all four groups, participants did not have any consensual vision of the risks of cannabis use or the definition of misuse. In the area of the prevention of cannabis use/misuse, while parents focused on the potential role of professionals and the media, thus minimizing their own educational and preventive role, professionals stressed the importance of parental control and education. Within the Swiss context, we conclude there exists an urgent need for information and clarification of the issues linked with cannabis use and misuse directed at parents and professionals.

A tale of two jurisdictions. Can Australia and Canada learn from each other's experience with cannabis control?

OBJECTIVE

To compare public health and legal policies to reduce the harm associated with cannabis use in Canada and Australia, given similarities between both countries.

METHOD

A review of the epidemiological and health policy literature.

RESULTS

Although both countries have adopted harm minimization, a continued heavy reliance on legislative and punitive approaches in both Canada and Australia has failed to arrest the increase in cannabis use, especially among young people. A Senate inquiry in Canada has recommended the liberalization of laws on the possession and use of cannabis, while tightening legislation against operating vehicles or machinery while intoxicated.

CONCLUSIONS

Existing policies are not evidence-based and lead to adverse outcomes such as criminalization of otherwise law-abiding citizens and diversion of resources from more effective policing or health service initiatives.

Role of endocannabinoid system in mental diseases

In the last decade, a large number of studies using Delta9-tetrahydrocannabinol (THC), the main active principle derivative of the marijuana plant, or cannabinoid synthetic derivatives have substantially contributed to advance the understanding of the pharmacology and neurobiological mechanisms produced by cannabinoid receptor activation. Cannabis has been historically used to relieve some of the symptoms associated with central nervous system disorders. Nowadays, there are anecdotal evidences for the use of cannabis in many patients suffering from multiple sclerosis or chronic pain. Following the historical reports of the use of cannabis for medicinal purposes, recent research has highlighted the potential of cannabinoids to treat a wide variety of clinical disorders. Some of these disorders that are being investigated are pain, motor dysfunctions or psychiatric illness. On the other hand, cannabis abuse has been related to several psychiatric disorders such as dependence, anxiety, depression, cognitive impairment, and psychosis. Considering that cannabis or cannabinoid pharmaceutical preparations may no longer be exclusively recreational drugs but may also present potential therapeutic uses, it has become of great interest to analyze the neurobiological and behavioral consequences of their administration. This review attempts to link current understanding of the basic neurobiology of the endocannabinoid system to novel opportunities for therapeutic intervention and its effects on the central nervous system.

Cannabis use and mental health in young people: cohort study

OBJECTIVE

To determine whether cannabis use in adolescence predisposes to higher rates of depression and anxiety in young adulthood.

DESIGN

Seven wave cohort study over six years.

SETTING

44 schools in the Australian state of Victoria.

PARTICIPANTS

A statewide secondary school sample of 1601 students aged 14-15 followed for seven years.

MAIN OUTCOME MEASURE

Interview measure of depression and anxiety (revised clinical interview schedule) at wave 7.

RESULTS

Some 60% of participants had used cannabis by the age of 20; 7% were daily users at that point. Daily use in young women was associated with an over fivefold increase in the odds of reporting a state of depression and anxiety after adjustment for intercurrent use of other substances (odds ratio 5.6, 95% confidence interval 2.6 to 12). Weekly or more frequent cannabis use in teenagers predicted an approximately twofold increase in risk for later depression and anxiety (1.9, 1.1 to 3.3) after adjustment for potential baseline confounders. In contrast, depression and anxiety in teenagers predicted neither later weekly nor daily cannabis use.

CONCLUSIONS

Frequent cannabis use in teenage girls predicts later depression and anxiety, with daily users carrying the highest risk. Given recent increasing levels of cannabis use, measures to reduce frequent and heavy recreational use seem warranted.

Cannabis use and traffic accidents in a birth cohort of young adults

OBJECTIVE

to examine linkages between cannabis use and traffic accident risks in a birth cohort of 907 young New Zealanders studied from 18 to 21 years.

METHODS

during the course of a 21-year longitudinal study of a birth cohort of 907 New Zealand born children information was gathered on (a) annual frequency of cannabis use over the period from 18 to 21 years; (b) annual rates of traffic accidents during the period 18-21 years; (c) measures of driver behaviours and characteristics. The association between cannabis use and traffic accident risk was examined among the 907 sample members who reported driving a motor vehicle between the ages of 18 and 21 years.

RESULTS

there were statistically significant relationships between reported annual cannabis use and annual accident rates. This association was present only for 'active' accidents in which driver behaviours contributed to the accident; those using cannabis more than 50 times per year had estimated rates of active accidents that were 1.6 (95% CI 1.2-2.0) times higher than the rate for non-users. However, statistical control for driver behaviours and characteristics related to cannabis use (drink driving behaviour; risky/illegal driving behaviours; driver attitudes; gender) eliminated the association between cannabis use and traffic accident risks.

CONCLUSIONS

although cannabis use was associated with increased risks of traffic accidents among members of this birth cohort, these increased risks appear to reflect the characteristics of the young people who used cannabis rather than the effects of cannabis use on driver performance.

Preliminary study of chronic pain patients' concerns about cannabinoids as analgesics

OBJECTIVE

This was a preliminary investigation of patients' beliefs about cannabinoids and the associations between those beliefs, beliefs about medication, and personal and pain variables with regard to patients' willingness to try cannabinoids as analgesics.

DESIGN

A self-completion questionnaire was used.

SETTING

The investigation took place in an outpatient pain clinic.

PATIENTS

Sixty-seven patients with chronic pain were involved.

OUTCOME MEASURES

The outcome measures were patients' stated willingness to use cannabinoids and the extent of their agreement or disagreement with statements concerning cannabinoids and medicines in general.

RESULTS

Fifty-two percent of patients were doubtful about taking cannabinoids: unwillingness was strongly associated with specific concerns about side effects, addiction, tolerance, and losing control but not with general beliefs about medication or personal or medical variables other than age.

CONCLUSIONS

The concerns of patients with chronic pain about taking cannabinoids as analgesics may reduce their utility and efficacy; accurate information is required to counter this effect.