Effects of stimulant drugs on actual and simulated driving: perspectives from four experimental studies conducted as part of the DRUID research consortium

Driving under the influence of drugs: Correlation between blood psychoactive drug concentrations and cognitive impairment. A narrative review taking into account forensic issues

Driving under the influence of alcohol has been shown to increase the risk of involvement in road traffic collisions (RTCs) however, less is known about the effects of illicit drugs, and a clear correlation between drug concentrations and RTC risk is still debated. The goal of this narrative review is to assess the current literature regarding the most detected psychoactive drugs in RTC (ethanol, amphetamines, cannabis, opioids and cocaine), in relation to driving performance. Evidence on impaired driving due to psychoactive substances, forensic issues relating to the assessment of the impact of drugs, blood cut-off values proposed to date as well as scientific basis for proposed legislative limits are discussed. At present there is no unequivocal evidence demonstrating a clear dose/concentration dependent impairment in many substances. Per se and zero tolerance approaches seem to have negative effect on drugged driving fatalities. However, the weight of these approaches needs further investigation.

•

Driving under the influence of psychotropic substances has become a widespread phenomenon.

•

Only a few substances have been reported to have a clear dose/concentration dependent impairment.

•

Statistically significant differences should not be considered as clinically significant per se

•

There is wide variability in legislative cut-offs.

•

Detection limits seems to be the most public safety-oriented legislative approach.

Patterns, Consequences, and Motives in Simultaneous Use of Prescription Stimulant Medication with Alcohol and Marijuana

Nonmedical use of prescription stimulants (NPS) continues to be a concern on college campuses. Previous research demonstrates a strong link between NPS and use of other substances, particularly alcohol and marijuana among college students. Simultaneous use of NPS with other substances has become an increasing concern. Given the high rates of NPS and simultaneous NPS with other substances, research examining substance use patterns and motives among students is warranted. Method: This study evaluated group differences in alcohol and marijuana use patterns, consequences, and motives among college students: a) with no NPS history (No NPS); b) engaged in NPS with no simultaneous use (Non-Sim NPS); and c) engaged in simultaneous NPS with alcohol and/or marijuana (Sim NPS). Participants included 1,108 students from three universities who reported past-year marijuana and alcohol use. Results: Overall, 32.8% reported lifetime NPS with 12.5% indicating NPS in the previous 3 months, of which 51.1% reported simultaneous NPS with alcohol and 40.2% with marijuana. Significant group differences for all drinking and marijuana outcomes were found, with heaviest rates among the Sim NPS group, followed by the Non-Sim NPS group, and the No NPS group. The Sim NPS group reported greater motives for using marijuana to alter the effects of other substances. Conclusions: College students engaged in simultaneous NPS with alcohol and marijuana are a high-risk group that should be the focus of prevention and intervention programs in the campus setting.

Trends in the use of psychoactive substances by truck drivers in São Paulo State, Brazil: A time-series cross sectional roadside survey (2009-2016)

OBJECTIVE

Truck drivers represent a group that is susceptible to the use of stimulant substances to reduce the symptoms of fatigue, which may be caused by a stressful and exhausting work environment. The use of psychoactive substances may increase the risk for involvement in road traffic crashes. Previous studies have demonstrated that amphetamine, cocaine, and cannabis are the 3 main drugs used by Brazilian truck drivers. We studied the prevalence of amphetamine, benzoylecgonine (indicating use of cocaine), and Δ-9-tetrahydrocannabinol-9-carboxylic acid (THC-COOH; indicating use of cannabis) in urine samples from truck drivers in the state of São Paulo, Brazil, using the same methodology during 8 years (2009-2016).

METHODS

Samples were collected during a health program supported by the Federal Highway Police. Toxicological analyses were performed using immunoassays and gas chromatography-mass spectrometry.

RESULTS

The total prevalence of illicit drugs was 7.8%. Benzoylecgonine was the most prevalent substance (3.6%), followed by amphetamine (3.4%) and THC-COOH (1.6%). We found the highest drug prevalence in 2010 (11.3%) and the lowest in 2011 (6.1%). We could detect a slight change in the pattern of stimulant use: until 2010, amphetamine was the most prevalent substance; however, in 2011 benzoylecgonine became the most frequently detected substance. This lasted until 2015, probably due to changes in Brazilian legislation regarding appetite suppressants; the most common one is metabolized to amphetamine.

CONCLUSION

These data show that the use of psychoactive substances by truck drivers in Brazil did not decrease during the study period. This reinforces the need for further preventive measures to reduce drug use among drivers, which could lead to a decrease in traffic crashes in Brazil.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prevalence of alcohol and drug use in injured British Columbia drivers

OBJECTIVES

Determine the prevalence of drug use in injured drivers and identify associated demographic factors and crash characteristics.

DESIGN

Prospective cross-sectional study.

SETTING

Seven trauma centres in British Columbia, Canada (2010-2012).

PARTICIPANTS

Automobile drivers who had blood obtained within 6 h of a crash.

MAIN OUTCOME MEASURES

We analysed blood for cannabis, alcohol and other impairing drugs using liquid chromatography/mass spectrometry (LCMS).

RESULTS

1097 drivers met inclusion criteria. 60% were aged 20-50 years, 63.2% were male and 29.0% were admitted to hospital. We found alcohol in 17.8% (15.6% to 20.1%) of drivers. Cannabis was the second most common recreational drug: cannabis metabolites were present in 12.6% (10.7% to 14.7%) of drivers and we detected Δ-9-tetrahydrocannabinol (Δ-9-THC) in 7.3% (5.9% to 9.0%), indicating recent use. Males and drivers aged under 30 years were most likely to use cannabis. We detected cocaine in 2.8% (2.0% to 4.0%) of drivers and amphetamines in 1.2% (0.7% to 2.0%). We also found medications including benzodiazepines (4.0% (2.9% to 5.3%)), antidepressants (6.5% (5.2% to 8.1%)) and diphenhydramine (4.7% (3.5% to 6.2%)). Drivers aged over 50 years and those requiring hospital admission were most likely to have used medications. Overall, 40.1% (37.2% to 43.0%) of drivers tested positive for alcohol or at least one impairing drug and 12.7% (10.7% to 14.7%) tested positive for more than one substance.

CONCLUSIONS

Alcohol, cannabis and a broad range of other impairing drugs are commonly detected in injured drivers. Alcohol is well known to cause crashes, but further research is needed to determine the impact of other drug use, including drug-alcohol and drug-drug combinations, on crash risk. In particular, more work is needed to understand the role of medications in causing crashes to guide driver education programmes and improve public safety.

Drug use and fatal motor vehicle crashes: a case-control study

Drugged driving is a serious safety concern, but its role in motor vehicle crashes has not been adequately studied. Using a case-control design, the authors assessed the association between drug use and fatal crash risk. Cases (n=737) were drivers who were involved in fatal motor vehicle crashes in the continental United States during specific time periods in 2007, and controls (n=7719) were participants of the 2007 National Roadside Survey of Alcohol and Drug Use by Drivers. Overall, 31.9% of the cases and 13.7% of the controls tested positive for at least one non-alcohol drug. The estimated odds ratios of fatal crash involvement associated with specific drug categories were 1.83 [95% confidence interval (CI): 1.39, 2.39] for marijuana, 3.03 (95% CI: 2.00, 4.48) for narcotics, 3.57 (95% CI: 2.63, 4.76) for stimulants, and 4.83 (95% CI: 3.18, 7.21) for depressants. Drivers who tested positive for both alcohol and drugs were at substantially heightened risk relative to those using neither alcohol nor drugs (Odds Ratio=23.24; 95% CI: 17.79, 30.28). These results indicate that drug use is associated with a significantly increased risk of fatal crash involvement, particularly when used in combination with alcohol.

Effects of three therapeutic doses of codeine/paracetamol on driving performance, a psychomotor vigilance test, and subjective feelings

RATIONALE

Some recent pharmacoepidemiological studies revealed an elevated risk of driving accidents after opioid analgesics uses. Among analgesics, codeine is often associated with paracetamol in numerous pharmaceutical specialties.

OBJECTIVES

The objective of this study was to evaluate the dose-effect relationship of three usual therapeutic doses of codeine/paracetamol on driving ability, psychomotor performance, subjective alertness, in link with blood concentrations in healthy young volunteers.

METHODS

Driving performance, responses to psychomotor vigilance tests, and scales reflecting alertness were evaluated during the morning after drug intake in a double-blind, randomized, placebo-controlled study. Sixteen healthy volunteers (23.4 ± 2.7 years old, 8 men and 8 women) participated in this balanced, cross-over study. Three doses of codeine/paracetamol (20/400, 40/800, 60/1200 mg) were evaluated against placebo. Two blood samples were collected, 1 and 4 h after drug intake. In serum, codeine and morphine concentrations were determined in serum using high-performance liquid chromatography electrospray ionization-tandem mass spectrometry, and paracetamol concentrations using fluorescence polarization immunoassay.

RESULTS

Driving and psychomotor performance were not affected by any of the three codeine/paracetamol doses. However, significant, though modest, correlations were observed between the driving parameters and both morphine and codeine blood concentrations.

CONCLUSIONS

This study did not reveal any significant impairment in performance due to the three therapeutic doses used in healthy young volunteers. However, the relationships between drug blood concentration and behavioral measures suggest that an inter-subject variability in blood concentration may influence the power of the observed drug effect.

Alcohol- or drug-use disorders and motor vehicle accident mortality: a retrospective cohort study

A large body of research has linked alcohol consumption and motor vehicle accidents (MVAs), but far fewer studies have estimated the risk of MVA fatality among drug users. Our study addresses this gap. We identified cohorts of individuals hospitalized in California from 1990 to 2005 with ICD-9 diagnoses of methamphetamine- (n=74,170), alcohol- (n=592,406), opioids- (n=68,066), cannabis- (n=47,048), cocaine- (n=48,949), or polydrug-related disorders (n=411,175), and these groups were followed for up to 16 years. Age-, sex-, and race-adjusted standardized mortality rates (SMRs) for deaths due to MVAs were generated in relation to the California general population. Standardized MVA mortality ratios were elevated across all drug cohorts: alcohol (4.5, 95% CI, 4.1-4.9), cocaine (3.8, 95% CI, 2.3-5.3), opioids (2.8, 95% CI, 2.1-3.5), methamphetamine (2.6, 95% CI, 2-3.1), cannabis (2.3, 95% CI, 1.5-3.2) and polydrug (2.6, 95% CI, 2.4-2.9). Males and females had similar MVA SMRs. Our large, population-based study found elevated risk of MVA mortality across all cohorts of individuals with alcohol- or drug-use disorders. Given that illicit drug users are often unaware of or misperceive the impacts of drug use on safe driving, it may be important for health-service or public-health interventions to address such biases and improve road safety.