Dose related risk of motor vehicle crashes after cannabis use

The role of Delta(9)-tetrahydrocannabinol (THC) in driver impairment and motor vehicle crashes has traditionally been established in experimental and epidemiological studies. Experimental studies have repeatedly shown that THC impairs cognition, psychomotor function and actual driving performance in a dose related manner. The degree of performance impairment observed in experimental studies after doses up to 300 microg/kg THC were equivalent to the impairing effect of an alcohol dose producing a blood alcohol concentration (BAC) >/=0.05 g/dl, the legal limit for driving under the influence in most European countries. Higher doses of THC, i.e. >300 microg/kg THC have not been systematically studied but can be predicted to produce even larger impairment. Detrimental effects of THC were more prominent in certain driving tasks than others. Highly automated behaviors, such as road tracking control, were more affected by THC as compared to more complex driving tasks requiring conscious control. Epidemiological findings on the role of THC in vehicle crashes have sometimes contrasted findings from experimental research. Case-control studies generally confirmed experimental data, but culpability surveys showed little evidence that crashed drivers who only used cannabis are more likely to cause accidents than drug free drivers. However, most culpability surveys have established cannabis use among crashed drivers by determining the presence of an inactive metabolite of THC in blood or urine that can be detected for days after smoking and can only be taken as evidence for past use of cannabis. Surveys that established recent use of cannabis by directly measuring THC in blood showed that THC positives, particularly at higher doses, are about three to seven times more likely to be responsible for their crash as compared to drivers that had not used drugs or alcohol. Together these epidemiological data suggests that recent use of cannabis may increase crash risk, whereas past use of cannabis does not. Experimental and epidemiological research provided similar findings concerning the combined use of THC and alcohol in traffic. Combined use of THC and alcohol produced severe impairment of cognitive, psychomotor, and actual driving performance in experimental studies and sharply increased the crash risk in epidemiological analyses.     

Drugs, alcohol and driving.

Driving a car is a complex psychomotor and perceptual task which is subject to impairment by many factors. Several workers have studied the potential effects of drugs and alchol in crash production by epidemiological and laboratory studies. Both types of studies have yielded useful data but their limitations must be borne in mind when applying the results in pratice. Alcohol is obviously the most common single cause of traffic accidents. A progessively increased risk with increasing blood alcohol levels is well documented; fatigue and/or drugs increase this risk. Drugs are related much more infrequently to traffic accidents although on the basis of statistics, there is a potential risk with drug use. However, drugs alone are not as important as alcohol. The most significant drugs as regards driving risk are obviously certain antianxiety agents, hypnotics, stimulants, hallucinogens, marihuana, lithium and narcotic analgesics, as well as ganglionic blocking agents, insulin and sulphonylurea derivates. Patients should not drive after taking these drug until they are objectively fully alert and capable. Anticholinergics, antihistamines, antidepressants, antipsychotics, phenybutazone, indomethacin, alpha-methyldopa, and beta-blockers may in some cases cause central side effects (e.g. drowsiness) strong enough to affect driving performance. After starting therapy with these drugs, or after a significant change in dose, driving should be avoided until it is known that unwanted effects do not occur. Psychotropic drugs may enhance the deleterious effect of alcohol, and with most hypnotics there is still an effect the next morning. Some drugs (e.g. anticonvulsants or antiparkinsonian drugs) may make driving safer, but the disease (epilepsy, Parkinsonism, cardiovascular diseases, psychic disorders, etc.) ofter precludes driving. Clinicians should warn their patients about an impairment of driving skills if this is likely to occur due to the drug or the illness concerned.     

Effects of combined alcohol and benzodiazepine: a review

Both human and animal studies relating to the combined effects of alcohol and benzodiazepine (BZD) are reviewed. Although the combination of alcohol and BZD is sometimes associated with drug-induced deaths, drug overdoses and traffic accidents or fatalities, epidemiological information is lacking on the true extent of the combined abuse and on the patterns and prevalence of use of these two drugs. Since BZD are widely used for the short- and long-term treatment of alcoholics, these patients are deemed more at risk of developing BZD or alcohol/BZD dependence than the general population. There is a dire need for large-scale controlled studies concerning the efficacy of BZD in the long-term treatment of alcoholics. Compared to men, women are at a higher risk as far as the potential for BZD addiction is concerned, since they tend to use BZD more often. Epidemiologic studies on the patterns of use of BZD, alcohol or alcohol/BZD in pregnant women are called for. Animal models are also needed to ascertain whether prenatal exposure to both alcohol and BZD can impart long-lasting behavioral changes in the progeny. It is possible that BZD can exacerbate the damaging prenatal effects of alcohol.     

A review of drug use and driving: epidemiology, impairment, risk factors and risk perceptions

The existing literature on the prevalence of drug driving, the effects of drugs on driving performance, risk factors and risk perceptions associated with drug driving was reviewed. The 12-month prevalence of drug driving among the general population is approximately 4%. Drugs are detected commonly among those involved in motor vehicle accidents, with studies reporting up to 25% of accident-involved drivers positive for drugs. Cannabis is generally the most common drug detected in accident-involved drivers, followed by benzodiazepines, cocaine, amphetamines and opioids. Polydrug use is common among accident-involved drivers. Studies of impairment indicate an undeniable association between alcohol and driving impairment. There is also evidence that cannabis and benzodiazepines increase accident risk. The most equivocal evidence surrounds opioids and stimulants. It is apparent that drugs in combination with alcohol, and multiple drugs, present an even greater risk. Demographically, young males are over-represented among drug drivers. Although there is an association between alcohol use problems and drink driving, it is unclear whether such an association exists between drug use problems and drug driving. Evidence surrounding psychosocial factors and driving behaviour is also equivocal at this stage. While most drivers perceive drug driving to be dangerous and unacceptable, there is less concern about impaired driving among drug drivers and drink drivers than from those who have not engaged in impaired driving. Risk perceptions differ according to drug type, with certain drugs (e.g. cannabis) seen as producing less impairment than others (e.g. alcohol). It is concluded that drug driving is a significant problem, both in terms of a general public health issue and as a specific concern for drug users. [Kelly E, Darke S, Ross J. A review of drug use and driving: epidemiology, impairment, risk factors and risk perceptions. Drug Alcohol Rev 2004;23:319-344]     

Demographic and substance use factors related to violent and accidental injuries: results from an emergency room study.

OBJECTIVE: The primary goal of this study was to identify demographic and substance use factors associated with violent injuries, accidental injuries, and medical conditions or illnesses (non-injured). METHOD: Data were examined from a sample of 1701 admissions to emergency rooms at two Canadian hospitals. These patients were interviewed and provided urine samples to detect the presence of drug metabolites for alcohol, THC, benzodiazepines, barbiturates, morphine, and codeine. RESULTS: Those with violent injuries were significantly (P<0.0001) more likely to be male and have lower incomes compared with both the accidental injury and non-injury groups. About 37% of violent injuries occurred at a bar or restaurant, which was significantly more than 3% for accidental injuries and 2% for non-injuries (P<0.00001). The violent injury group was significantly more likely than the other two groups to report feeling the effects of alcohol at the time of the injury and to report negative consequences of alcohol use (P<0.00001). Furthermore, about 42% of those with violent injuries had a blood alcohol level (BAL) over 80 mg% compared to only 4% with accidental injuries (P<0.00001) and 2% of non-injuries (P<0.00001). In terms of drug tests for other substances, the violent injury group was significantly more likely to test positive for benzodiazepines than the accidental injury group (P<0.01) while all between group comparisons for other drugs were not significant.     

Speed freaks? A literature review detailing the nature and prevalence of dance drugs and driving

Considerable interest has lately been expressed in motor car driving whilst under the influence of drugs. Unlike depressant drugs (e.g. alcohol) dance drugs are often perceived to enhance driving skills. The physical effects and the current lack of police roadside testing are possible contributing reasons for dance drug driving. This paper aims to show through a literature review on the subject, the demographics of those involved in dance drug driving and the extent to which certain dance drugs are implicated in drug driving incidents. Drug driving is found to be highest amongst the 18-35 year age group and more prevalent amongst adult males. Prevalence figures for driving under the influence of individual drugs are also given. The numbers of people involved in accidents/fatalities and testing positive for amphetamine, cocaine and other dance drugs is small. Although self-reporting especially of illegal activities is difficult to accurately evaluate, most of the reported studies use actual blood/urine samples and so can be considered accurate. The literature does not highlight any real concerns regarding dance drug driving in terms of prevalence although it does highlight the paucity of research in this area, in particular 'Culture E and driving'.     

Drug testing in the Australian workplace: overview of the issues

This paper is an overview of the issues surrounding employee drug testing programs as they apply to the Australian workplace. Drug testing may be seen within a historical context of control over workers. Its practice is most prevalent in the USA, but it is also occurring in Australia, Canada and England. It is undeniable that alcohol and other drug use causes significant problems in many workplaces, though the apparently substantial costs to industry and the prevalence of drug use among workers are difficult to estimate with any degree of precision. Drug testing programs in the workplace appear to have majority public support in the USA and are even supported by some unions in Australia and the USA; there are, however, critics of the programs. The evaluation evidence to date is sparse, but is promising in that it suggests that drug testing programs can be responsible for reducing the prevalence of drug use among workers as well as dramatically reducing company costs for absenteeism, accidents and medical insurance claims. However, due to methodological shortcomings one cannot state conclusively that drug testing programs are as effective as they appear to be. Research using more rigorous designs and generating data that can be compared across studies is needed. Distasteful though drug testing is, we may see benefits in its use, similar in concept to random breath testing on our roads. Many of the procedural and legal problems in early US programs have been eliminated, refinements which should assist Australians. The legal issues, however, are quite different in Australia. A drug testing program should not be the sole remedy for reducing alcohol and other drug problems in the workplace and such a program must also be accompanied by rehabilitation and educational components. Ethical issues are briefly discussed.     

Addressing gay men's use of methamphetamine and other substances

Gay men's use of methamphetamine has aroused great anxiety. In some countries such as the USA and Australia as many as 40% of gay men use this drug, while use is lower in others such as the UK. However, across all these countries gay men's use of other substances such as alcohol, poppers and cannabis surpasses that of methamphetamine. Recent evidence from case-crossover studies suggests that use of not only methamphetamine but also of alcohol, cannabis, poppers, cocaine, amphetamines and Viagra is associated with increased risk behaviour during episodes of anal intercourse. However national drugs and alcohol strategies do not refer to gay men, drug treatment services tend to focus on opiates and do not target gay men, and HIV prevention for gay men rarely mentions use of substances other than methamphetamine. This is a missed opportunity given the evidence for the effectiveness or drug treatment and prevention interventions, and evidence that such interventions can be tailored to gay clients.     

Psychomotor effects of astemizole and chlorpheniramine, alone and in combination with alcohol

Road traffic accidents are a leading cause of mortality and morbidity, and their association with alcohol and drugs such as minor tranquillizers is well established (Seppala et al., 1979). There is also epidemiological evidence to associate the older, sedative antihistamines with motorcycle accidents (Skegg et al., 1979). Astemizole is a recently introduced H1-antagonist which, unlike older antihistamines, does not cause central nervous system sedation. The present study was designed to compare the effects of astemizole and chlorpheniramine, alone and in combination with alcohol, on an objective measure of psychomotor performance relating to car-driving ability.     

A drug policy for our times

Three erroneous assumptions have influenced illicit drug abuse control policy. The first states that dependence-producing drugs are not different from many other substances consumed by people. This assumption underestimates the inherent neuro-behavioural properties of dependence-producing drugs that lead their users to adopt a compulsive pattern of daily consumption that is damaging to health. The second assumption states that even a young person may learn to use these drugs in a reasonable and responsible fashion, taking advantage of their redeeming qualities and avoiding their damaging effects. This assumption overestimates the ability of the human neocortex (new brain) to override the chemical stimuli induced by dependence-producing drugs in the pleasure and reward centres, which seem to be located in the limbic system of the old primitive brain. The third assumption states that social acceptance and commercial availability of illicit drugs would eliminate the social costs associated with their illegal traffic, which breeds crime and corruption. This assumption ignores historical precedents and the results of epidemiological surveys that demonstrate the damaging effects that social acceptance of these drugs and their widespread use may have on the individual and society. Surveys of drug consumers indicate that the percentage of addicts is significantly related to the dependence-producing potential of the drug used. In a population where alcohol is commonly consumed, 7-9 per cent of the consumers drink in amounts that are damaging to health. In a population where cannabis is socially accepted and easily available, more than half of cannabis consumers use the drugs in doses damaging to health. Approximately 90-95 per cent of cocaine or heroin users consume their drug of choice on a daily basis. Therefore, the dependence-producing potential of cannabis and that of cocaine or heroin would be, respectively, 7 and 14 times greater than the dependence potential of alcohol. Current illicit drug control policy should be based on scientific evidence and successful historical precedents, some of which are summarized in this article. This policy should concurrently aim at curtailing the supply of illicit drugs and reducing their demand.     

Illicit drugs, medications and traffic accidents

The European Union (EU) has 25 member-states and 455 million inhabitants. Statistics on traffic accidents in the EU show that more than 45,000 people are killed annually, including 5200 in France. At the same time, nearly two million persons in the EU require medical treatment for traffic-accident-related injuries, including 109,000 in France. In addition, traffic accidents are the major cause of death of those individuals aged 15 to 24 years. One third of the EU inhabitants will be hospitalized during their life due to a traffic accident with a cost over 160 billion euro (2-3% of the Gross Domestic Product). An important contributing factor to crashes is the use of alcohol and/or illicit drugs or medication when driving, as they exert negative effects on cognition and psychomotor functions. For illicit drugs, abuse of cannabis with or without alcohol is a major concern for the EU. In fact, three million Europeans use cannabis daily and 80% of them drive after use. A number of French studies since 1999 have underlined the high prevalence of cannabis found in the blood of injured or killed drivers. From medical or judicial observations, it is clear that cannabis use increases the risk of traffic accidents. Many groups outside Europe have also shown the association between drug abuse and crashes. The number of casualties related to certain medicines, especially benzodiazepines remains at a high level, particularly in the elderly. In many countries the prevalence of medicinal drugs associated with car accidents is higher than with cannabis. Annex III of the European Union Council Directive of July the 29th 1991 in fact states that a driving license should not be issued to or renewed for applicants or drivers who are dependent on psychotropic substances or use them regularly. Recently, France has categorized the medicinal drugs available in the country by using three pictograms: level one yellow, "be careful"; level two orange, "be very careful"; level three red, "don't drive". It is an important campaign that increases awareness among the public and the medical professionals about the potential dangerous effects of medicinal drugs when driving. The EU objective of reducing the number of fatalities to 25,000 by 2010 will require strengthening measures against the use of alcohol, illicit and medicinal drugs by not well-informed drivers. It is not only a really great challenge, but also a significant investment towards improving public health in France as well as in Europe.     

Teenagers do not always lie: characteristics and correspondence of telephone and in-person reports of adolescent drug use

Because of the widespread use of drugs by adolescents, there is demand for scientific rigor in sampling and accuracy in methods for ascertaining drug use patterns. The present study: (1) characterized adolescents who responded to advertisements for marijuana users; (2) compared rates of drug use reported on the telephone versus an on-site interview; and (3) examined drug use patterns as a function of parental awareness of drug use. Adolescents, identifying themselves as marijuana users during telephone interviews, reported more use of other drugs than those denying marijuana use. There was a high degree of correspondence between telephone and on-site interviews for all drugs except alcohol, which was reported at a higher rate on-site. Of those reporting marijuana use in the past week, 69% tested positive for marijuana in their urine-drug screens. Finally, marijuana and alcohol use patterns were higher among adolescents whose parents were aware of drug use than those whose parents indicated that their adolescent did not use marijuana. These results indicate that adolescents are willing to self-identify as marijuana users and report drug and alcohol use during telephone interviews. Additionally, parents appear to become more aware of their adolescent's drug use with increased frequency of use.     

Is cannabis a gateway drug? Testing hypotheses about the relationship between cannabis use and the use of other illicit drugs

We outline and evaluate competing explanations of three relationships that have consistently been found between cannabis use and the use of other illicit drugs, namely, (1) that cannabis use typically precedes the use of other illicit drugs; and that (2) the earlier cannabis is used, and (3) the more regularly it is used, the more likely a young person is to use other illicit drugs. We consider three major competing explanations of these patterns: (1) that the relationship is due to the fact that there is a shared illicit market for cannabis and other drugs which makes it more likely that other illicit drugs will be used if cannabis is used; (2) that they are explained by the characteristics of those who use cannabis; and (3) that they reflect a causal relationship in which the pharmacological effects of cannabis on brain function increase the likelihood of using other illicit drugs. These explanations are evaluated in the light of evidence from longitudinal epidemiological studies, simulation studies, discordant twin studies and animal studies. The available evidence indicates that the association reflects in part but is not wholly explained by: (1) the selective recruitment to heavy cannabis use of persons with pre-existing traits (that may be in part genetic) that predispose to the use of a variety of different drugs; (2) the affiliation of cannabis users with drug using peers in settings that provide more opportunities to use other illicit drugs at an earlier age; (3) supported by socialisation into an illicit drug subculture with favourable attitudes towards the use of other illicit drugs. Animal studies have raised the possibility that regular cannabis use may have pharmacological effects on brain function that increase the likelihood of using other drugs. We conclude with suggestions for the type of research studies that will enable a decision to be made about the relative contributions that social context, individual characteristics, and drug effects make to the relationship between cannabis use and the use of other drugs.     

Emerging ethical issues in pharmacogenomics: from research to clinical practice

Pharmacogenomics holds much promise for the application of genetic information to the improvement of clinical care. Ethical issues for pharmacogenomics arise at the intersection of the spheres of drug development and genetic testing. Clinical drug trial designs which use subject selection based on genotype must consider the features of scientific validity, social value and risk-benefit ratio, and later, the impact of this strategy on post-market studies and clinical use of drugs. Although the testing context for pharmacogenomic tests is different from other genetic tests, decisions to use any new clinical tests in medical practice will require evaluation of not only the benefit linked to improved drug use but also the risks arising in part from the scale of testing, predictive value and collateral potential of the genetic test. Integration of pharmacogenomic information into clinical practice will require clinical trials to assess their clinical usefulness, including the impact of tests on therapeutic outcomes. Trials will also be needed to demonstrate the effectiveness of education, informed consent and counseling.     

Drinking behaviour and social change among youths in Nigeria--a study of two cities

Earlier studies on alcohol use in Nigeria identified young and middle-aged male adults as mainly concerned. In the last decade however, there has been a noticeable trend of youths getting more and more involved in alcohol use. Some of these latter studies, apart from indicating the increasing involvement of the female sex, have also shown various pathologies associated with alcohol use in Nigeria youths. Most of these reports only looked at alcohol use in the broader context of drug and alcohol abuse in the Nigerian society. However, in the present cross-sectional study of drug use involving 2079 senior secondary school students in two major cities of Nigeria (Ibadan and Abeokuta), prevalence rates of alcohol use was 56% for Ibadan and 51.5% for Abeokuta. The male/female ratio of the users was 1.1:1 in Ibadan and 1.2:1 in Abeokuta. Males used alcohol significantly more than females in each of the two cities (P less than 0.025). Alcohol use was found more common among younger students in the lower school classes and also among those from higher and medium socioeconomic background. Among contributing factors were parental deprivation and delinquency. Alcohol users were also found to be more involved in accidents and the use of other psycho-active drugs than non-users.     

Factors related to self-reported violent and accidental injuries

The main objective of this study is to gain a better understanding of factors that distinguish violent and accidental injuries. A secondary analysis was conducted on data from a randomized telephone survey of 10 385 Canadian residents. Three groups were compared using chi-square tests and logistic regression analyses: respondents who reported no injuries in the previous year, those with at least one accidental injury and those with at least one violent injury. In the bivariate analyses, the violent injury group was significantly more likely than the accidental injury and non-injury groups to be single, widowed, separated or divorced, have more than five drinks on a usual drinking occasion, experience harmful effects of alcohol and to have used illicit drugs, such as cocaine and marijuana, and licit drugs, such as antidepressants and sleeping pills. Finally, the violent injury group was significantly more likely than those with non-violent injuries to report that the incident was related to either their own or someone else's alcohol or drug use. In the final multiple logistic regression analysis, variables significantly associated with injuries due to criminal victimizations compared with accidental injuries were being female, single, cocaine use of the injured and substance use of someone else during the injury.