The effects of moderate alcohol concentrations on driving and cognitive performance during ascending and descending blood alcohol concentrations

Drinking and driving: A systematic review of the impacts of alcohol consumption on manual and automated driving performance

INTRODUCTION

Almost a third of car accidents involve driving after alcohol consumption. Autonomous vehicles (AVs) may offer accident-prevention benefits, but at current automation levels, drivers must still perform manual driving tasks when automated systems fail. Therefore, understanding how alcohol affects driving in both manual and automated contexts offers insight into the role of future vehicle design in mediating crash risks for alcohol-impaired driving.

METHOD

This study conducted a systematic review on alcohol effects on manual and automated (takeover) driving performance. Fifty-three articles from eight databases were analyzed, with findings structured based on the information processing model, which can be extended to the AV takeover model.

RESULTS

The literature indicates that different Blood Alcohol Concentration (BAC) levels affect driving skills essential for traffic safety at various information processing stages, such as delayed reacting time, impaired cognitive abilities, and hindered execution of driving tasks. Additionally, the driver's driving experience, drinking habits, and external driving environment play important roles in influencing driving performance.

CONCLUSIONS

Future work is needed to examine the effects of alcohol on driving performance, particularly in AVs and takeover situations, and to develop driver monitoring systems.

PRACTICAL APPLICATIONS

Findings from this review can inform future experiments, AV technology design, and the development of driver state monitoring systems.

Acute administration of alprazolam, alcohol and their combination on cognitive performance and mood: A randomised, double-blind, placebo-controlled study

BACKGROUND

Recreational co-consumption of benzodiazepines and alcohol is a common practise; yet, the cognitive effects of this combination remain poorly understood. This study aimed to investigate the acute cognitive effects of combining a 1 mg dose of alprazolam with a moderate dose of alcohol (target 0.04% blood alcohol concentration (BAC)) in a non-clinical population.

METHODS

In this randomised, double-blind, placebo-controlled, crossover trial, participants completed computerised cognitive assessments and the brief biphasic alcohol effects scale (B-BAES) after consuming 1 mg of alprazolam, both with and without a moderate dose of alcohol (target 0.04% BAC).

RESULTS

Among 20 healthy participants (mean age = 28.6, SD ± 4.0 years, 60% female), we found that a peak BAC of 0.03% had no significant impact on cognitive performance. Both the individual use of alprazolam and its combination with alcohol resulted in impaired reaction time, digit vigilance, and verbal, spatial and numeric working memory tasks, although an additive effect when alcohol and alprazolam were consumed together was not evident. The most pronounced cognitive effects occurred at 100 min after dosing, coinciding with increased alprazolam concentrations. Sedative effects were heightened with alcohol, alprazolam and their combination while no stimulative effects were reported.

CONCLUSIONS

Our findings highlight the significant implications of a therapeutic dose of alprazolam on impairing cognitive performance. This is particularly relevant considering the frequency of non-medical alprazolam use. Future studies should explore different dosages, administration timings and long-term effects to inform the development of public health policies and guidelines regarding the combined use of alcohol and benzodiazepines.

The effects of cannabis and alcohol on driving performance and driver behaviour: a systematic review and meta-analysis

BACKGROUND AND AIMS

Cannabis and alcohol are frequently detected in fatal and injury motor vehicle crashes. While epidemiological meta-analyses of cannabis and alcohol have found associations with an increase in crash risk, convergent evidence from driving performance measures is insufficiently quantitatively characterized. Our objectives were to quantify the magnitude of the effect of cannabis and alcohol-alone and in combination-on driving performance and behaviour.

METHODS

Systematic review and meta-analysis. We systematically searched Academic Search Complete, CINAHL, Embase, Scopus, Google Scholar, MEDLINE, PsycINFO, SPORTDiscus and TRID. Of the 616 studies that underwent full-text review, this meta-analysis represents 57 studies and 1725 participants. We extracted data for hazard response time, lateral position variability, lane deviations or excursions, time out of lane, driving speed, driving speed variability, speed violations, time speeding, headway, headway variability and crashes from experimental driving studies (i.e. driving simulator, closed-course, on-road) involving cannabis and/or alcohol administration. We reported meta-analyses of effect sizes using Hedges' g and r.

RESULTS

Cannabis alone was associated with impaired lateral control [e.g. g = 0.331, 95% confidence interval (CI) = 0.212-0.451 for lateral position variability; g = 0.198, 95% CI = 0.001-0.395 for lane excursions) and decreased driving speed (g = -0.176, 95% CI = -0.298 to -0.053]. The combination of cannabis and alcohol was associated with greater driving performance decrements than either drug in isolation [e.g. g = 0.480, 95% CI = 0.096-0.865 for lateral position variability (combination versus alcohol); g = 0.525, 95% CI = 0.049-1.002 for time out of lane (versus alcohol); g = 0.336, 95% CI = 0.036-0.636 for lateral position variability (combination versus cannabis; g = 0.475, 95% CI = 0.002-0.949 for time out of lane (combination versus cannabis)]. Subgroup analyses indicated that the effects of cannabis on driving performance measures were similar to low blood alcohol concentrations. A scarcity of data and study heterogeneity limited the interpretation of some measures.

CONCLUSIONS

This meta-analysis indicates that cannabis, like alcohol, impairs driving, and the combination of the two drugs is more detrimental to driving performance than either in isolation.

The hazardous (mis)perception of Self-estimated Alcohol intoxication and Fitness to drivE-an avoidable health risk: the SAFE randomised trial

BACKGROUND

Worldwide, alcohol-related road traffic accidents represent a major avoidable health risk. The aim of this study was to evaluate the accuracy of self-estimating the degree of acute alcohol intoxication regarding the legal driving limit, and to identify risk factors for misjudgement.

METHODS

In this prospective randomised controlled crossover trial, 90 social drinkers (mean age 23.9 ± 3.5 years, 50% female) consumed either beer or wine. Study group subjects were made aware when exceeding the legal driving limit (BrAC = 0.05%). Controls received no information about their BrAC. For crossover, beer or wine were consumed in the opposite order.

RESULTS

39-53% of all participants exceeded the legal driving limit whilst under the impression to be still permitted to drive. Self-estimation was significantly more accurate on study day 2 (p = 0.009). Increasing BrAC positively correlated with self-estimation inaccuracy, which was reproducible during crossover. Multiple regression analysis revealed fast drinking and higher alcohol levels as independent risk factors for inaccurate self-estimation.

CONCLUSIONS

Social drinkers are commonly unaware of exceeding the legal driving limit when consuming alcohol. Self-estimating alcohol intoxication can be improved through awareness. Dedicated awareness programs, social media campaigns and government advice communications should be utilised to address this avoidable hazard. Trial registration The trial was registered prospectively at the Witten/Herdecke University Ethics Committee (trial registration number 140/2016 on 04/11/2016) and at the DRKS-German Clinical Trials Register (trial registration number DRKS00015285 on 08/22/2018-Retrospectively registered). Trial protocol can be accessed online.

Are blood and oral fluid Δ9-tetrahydrocannabinol (THC) and metabolite concentrations related to impairment? A meta-regression analysis

Blood and oral fluid Δ⁹-tetrahydrocannabinol (THC) concentrations are often used to identify cannabis-impaired drivers. We used meta-analytic techniques to characterise the relationships between biomarkers of cannabis use, subjective intoxication, and impairment of driving and driving-related cognitive skills. Twenty-eight publications and 822 driving-related outcomes were reviewed. Each outcome was measured in concert with one or more biomarkers of cannabis/THC use and/or subjective intoxication. Higher blood THC and 11-OH-THC concentrations, oral fluid THC concentrations and subjective ratings of intoxication were associated with greater impairment in 'other' (mostly occasional) cannabis users (p's<0.05). Blood 11-COOH-THC concentrations were associated with impairment after inhaling, but not orally ingesting, cannabis/THC. However t these 'biomarker-performance' relationships (R) were only very weak (blood THC_{post-ingestion}: -0.08; blood THC_{post-inhalation}: -0.10; blood 11-OH-THC_{post-ingestion}: -0.13), weak (blood 11-OH-THC_{post-inhalation}: -0.24; oral fluid THC_{post-inhalation}: -0.36; subjective intoxication: -0.29) or moderate (blood 11-COOH-THC_{post-inhalation}: -0.43) in strength. No significant biomarker-performance relationships were observed in 'regular' (weekly or more often) cannabis users (p's>0.10), although the analyses were less robust. Blood and oral fluid THC concentrations are relatively poor indicators of cannabis/THC-induced impairment.

The effects of alcohol intoxication on cognitive functions critical for driving: A systematic review

Alcohol is the most frequently detected substance in drivers involved in road traffic collisions. Given that up to 35% of fatal road collisions are alcohol-related, it is important to determine the influence of alcohol intoxication on driving-related skills. This review provides an updated and systematic evaluation of the available research concerning the effect of alcohol intoxication on cognitive functions critical for driving. Databases EBSCOhost, PsycInfo, PubMed, Scopus, Transport Research International Documentation (TRID) and Web of Science were searched for controlled trials examining the effect of alcohol on divided attention, executive functioning, perception, psychomotor skills, reaction time and/or vigilance. Fourteen studies met the inclusion criteria and were included in this review. We found that each of the cognitive domains assessed in this review showed impairment at blood alcohol concentrations equal to or below the legal driving limit in many jurisdictions. Future research could determine the effects of alcohol on cognitive functioning with greater accuracy by employing more consistent, reliable and comparable measures while considering the translation of deficits to real-life driving.

Intoxicated aggression: Do alcohol and stimulants cause dose-related aggression? A review

RATIONALE

Violence and drug use are significant public health challenges that are strongly linked. It is known that alcohol plays a major role in the causation of unnatural deaths and that stimulants like cocaine and amphetamine are often implicated in aggressive acts or violence. However, a clear causal relationship between these substances and aggression, and more specifically a blood concentration threshold at which intoxicated aggression emerges is lacking. In case of a crime and subsequent law enforcement, knowledge about dose-response relationships could be of pivotal importance when evaluating the role of alcohol and drugs in aggressive offences.

AIMS

The present review aimed to determine whether there is a causal relation between intoxication with these psychoactive substances and aggression, and to define blood concentration thresholds above which these substances elicit aggression.

METHODS

Empirical articles published between 2013 and 2017 and review papers containing the predefined search strings were identified through searches in the PubMed and Embase databases and additional reference list searches. The complete search query yielded 1578 publications. Initially all articles were manually screened by title and abstract. Articles with irrelevant titles, given the selected search terms and review aims were discarded. Remaining articles were carefully studied and those that did not comply with the main objectives of this review were discarded. At the end of this process, 167 titles were found eligible for review.

FINDINGS AND CONCLUSION

While placebo-controlled experimental studies clearly showed a causal link between alcohol and aggression, it is evident that such a link has not yet been established for cocaine and amphetamines. In case of alcohol, it is clear that there are various individual and contextual factors that may contribute to the occurrence of an aggressive act during intoxication. A clear threshold blood alcohol concentration has not been defined yet for alcohol, but a statistically significant increase of aggression has been demonstrated at a dose of 0.75 g/kg and higher. Future studies into intoxicated aggression should include multiple doses of alcohol and stimulants and take into account individual and contextual factors.

Effects of alcohol intoxication goggles (fatal vision goggles) with a concurrent cognitive task on simulated driving performance

Objective: Fatal vision goggles (FVGs) are image-distorting equipment used to simulate alcohol impairment in driver education programs. Unlike alcohol, which disrupts cognitive processes, FVG only induces visual impairment. Performing concurrent cognitive tasks while wearing FVG may reduce the wearer's attentional resources and provide a better simulation of alcohol intoxication. This study examined the impact of wearing FVG with/without administration of a concurrent cognitive task on simulated driving.Methods: Twenty-one males (23 ± 3 y, mean ± SD) participated in this randomized, repeated-measures study involving two experimental trials. In each trial, participants completed a baseline drive then an experimental drive under one of two conditions: (1) FVG and (2) FVG with additional cognitive demand (FVG + CD). The driving test included 3 separate scenarios (Task 1, 2, 3) lasting ∼5min each. Lateral (standard deviation of lane position [SDLP]; number of lane crossings [LCs]) and longitudinal control parameters (average speed; standard deviation of speed [SDSP]; distance headway; minimum distance headway) were monitored in Tasks 1 and 2. Latency to two different stimuli (choice reaction time [CRT]) was examined in Task 3.Results: In Task 1, SDLP and LC were unaffected by either condition. However, SDSP increased significantly from baseline with FVG, irrespective of cognitive demand. In Task 2, distance headway decreased significantly from baseline with FVG, but increased significantly with FVG + CD. Minimum distance headway was significantly decreased, while SDLP increased significantly and LC increased (although not statistically significant) in both conditions relative to baseline. In Task 3, a significant increase in CRT occurred with FVG + CD, but not with FVG alone.Conclusions: Wearing FVG negatively impacted simulated driving performance. However, effects were isolated to specific performance outcomes and were dependent on complexity of the driving task. Addition of a secondary cognitive task exacerbates the effects of FVG on select driving outcomes (i.e. lane position, SDSP), influences the effect direction on other measures (i.e. distance headway), and has a detrimental effect on reaction time to stimuli embedded in the scenario, that is not observed with FVG alone. Future studies using FVG as a surrogate means to alcohol intoxication should consider these results, informing methodological decisions to reduce potential for confounding effects.

Gaze entropy measures detect alcohol-induced driver impairment

Driving under the influence of alcohol is an ongoing cause of road traffic accidents. The biphasic nature of alcohol effects on subjective experience appears to contribute to the prevalence of drink-driving, as people perceive the declining phase of the BAC curve as recovery from intoxication and are more willing to drive despite significant impairments in objectively measured functions. The present study investigates whether alcohol-induced changes in gaze behaviour can be detected during engagement in a simulated driving task. In a repeated-measures and placebo-controlled design, this study examines the biphasic influence of moderate alcohol intake (0.6 g/kg) on measures of gaze behaviour and simulated driving performance. Twenty-two healthy young adults completed three driving sessions (baseline, ascending and descending) under two conditions (placebo, alcohol) while their eye movements were simultaneously recorded. The results revealed that gaze behaviour as measured by gaze transition entropy (GTE) and stationary gaze entropy (SGE) and driving performance measured by the standard deviation of lateral position (SDLP) of the vehicle, were significantly affected by alcohol across the ascending and descending sessions. The alcohol-induced reduction in GTE with an increase in SGE is discussed as alcohol's impact on top-down modulation of gaze resulting in more dispersed and erratic pattern of visual scanning. The observed changes in gaze behaviour also mediated the influence of alcohol upon driving performance. These results have significant implications for the development of driver monitoring systems that can detect alcohol-induced impairment.

Correlates of Breath Alcohol Concentration Among Driving Under the Influence Program Clients in Southern California

Understanding factors correlated with breath alcohol concentration (BrAC) at time of arrest for driving under the influence (DUI) may lead to informed rehabilitation programs. This study describes correlations between BrAC at time of arrest and sociodemographic, mental, and physical health, and alcohol-related characteristics among clients in a large California DUI Program. Client reported data ( n = 17,282) were collected at an intake from 2009 to 2014. BrACs ranged from 0.083% to 0.390%, with an average of 0.159% ( SD = 0.051), almost twice the legal limit in the state. Approximately 10.6% of the variance in BrAC was explained by 11 significant correlates. Two sociodemographic factors (age and race/ethnicity) as well as several alcohol-related characteristics were related to higher BrAC levels, whereas comorbid mental and physical health factors played less of a role. Factors associated with BrAC are complex and warrant further investigation to identify causality and inform future interventions.

Can an app help identify psychomotor function impairments during drinking occasions in the real world? A mixed-method pilot study

BACKGROUND

Being able to measure the acute effects of alcohol consumption on psychomotor functions in natural settings could be useful in injury prevention interventions. This study examined the feasibility and acceptability of collecting app-based measures of information processing, working memory, and gait stability during times of typical alcohol consumption among young adults.

METHODS

Ten young adults (aged 21-26) with hazardous drinking completed a baseline assessment and ecological momentary assessments (EMA) on 4 consecutive Fridays and Saturdays, every hour from 8 pm to 12 am. EMA assessed alcohol consumption and perceived intoxication, followed by a digit symbol substitution task (DSST), a visuospatial working memory task (VSWMT), and a 5-step tandem gait task (TGT). Exit interviews probed user experiences. Multilevel models explored relationships between estimated blood alcohol concentration (eBAC; mg/dL) and DSST and VSWMT performance.

RESULTS

Participants completed 32% of EMA. Higher rates of noninitiation occurred later in the evening and over time. In multilevel models, higher eBAC was associated with lower DSST scores. Eight out of 10 individuals had at least 1 drinking occasion when they did not perceive any intoxication. Lower DSST scores would identify impairment in 45% of these occasions. Exit interviews indicated that adding real-time feedback on task performance could increase awareness of alcohol effects.

CONCLUSIONS

Collecting app-based psychomotor performance data from young adults during drinking occasions is feasible and acceptable, but strategies to reduce barriers to task initiation are needed. Mobile DSST is sensitive to eBAC levels and could identify occasions when an individual may not perceive impairments.

Alcohol hangover impacts learning and reward processing within the medial-frontal cortex

It is common knowledge that alcohol intoxication impairs motor coordination, judgment, and decision making. Indeed, an abundance of literature links intoxication to impaired cognitive control that leads to accidents and injury. A broadening body of research, however, suggests that the impact of alcohol may continue beyond the point of intoxication and into the period of alcohol hangover. Here, we examined differences in the amplitude of reward positivity-a component of the human ERP associated with learning-between control and hangover participants. During performance of a learnable gambling task, we found a reduction in the reward positivity during alcohol hangover. Additionally, participants experiencing alcohol hangover demonstrated reduced performance in the experimental task in comparison to their nonhangover counterparts. Our results suggest that the neural systems that underlie performance monitoring and reward-based learning are impaired during alcohol hangover.

Driving under the influence of drugs: Perceptions and attitudes of New Zealand drivers

This study explored the patterns of drug driving in New Zealand by investigating 1) drivers' perceptions about impairment caused by legal and illegal drugs 2) countermeasures employed by drivers when under the influence of drugs (e.g., decisions not to drive) 3) drivers' attitudes about police enforcement of drug driving and 4) the factors that predict the likelihood of engaging in drug driving. Participants (n=434) were licensed drivers who completed an online questionnaire. Results of the questionnaire indicated that drivers rated hallucinogens and opiates as being the illegal drugs producing the highest level of driving impairment and cannabis the lowest. For legal drugs, sedatives were rated as having the highest driving impairment and anti-nausea and anti-depressants the lowest. Respondents' drug use history had an effect on their ratings of impairment for anti-anxiety drugs, anti-depressants, kava, sedatives, cannabis and hallucinogens such that drug users reported higher impairment ratings than Non-user. Making a decision not to drive after taking drugs was reported by users of alcohol (73.6%), cannabis (57.0%), strong painkillers (42.5%), and anti-depressants (10.0%). Respondents who reported drink driving were 3.26 times more likely to report drug driving than those reporting no drink driving. Respondents also showed greater acceptance towards driving under the influence of legal drugs (43.5%) compared to illegal drugs (10.3%). Those who did not have favourable attitudes about drug driving were less likely to report having driven under the influence of drugs. Drivers in this sample were less aware of the potential negative effects of legal drugs on driving compared to illegal drugs. More than half the respondents from this study acknowledged drug driving as a road safety issue which needs more resources dedicated to it.

Risk factors affecting injury severity determined by the MAIS score

OBJECTIVE

Traffic crashes result in a loss of life but also impact the quality of life and productivity of crash survivors. Given the importance of traffic crash outcomes, the issue has received attention from researchers and practitioners as well as government institutions, such as the European Commission (EC). Thus, to obtain detailed information on the injury type and severity of crash victims, hospital data have been proposed for use alongside police crash records. A new injury severity classification based on hospital data, called the maximum abbreviated injury scale (MAIS), was developed and recently adopted by the EC. This study provides an in-depth analysis of the factors that affect injury severity as classified by the MAIS score.

METHOD

In this study, the MAIS score was derived from the International Classification of Diseases. The European Union adopted an MAIS score equal to or greater than 3 as the definition for a serious traffic crash injury. Gains are expected from using both police and hospital data because the injury severities of the victims are detailed by medical staff and the characteristics of the crash and the site of its occurrence are also provided. The data were obtained by linking police and hospital data sets from the Porto metropolitan area of Portugal over a 6-year period (2006-2011). A mixed logit model was used to understand the factors that contribute to the injury severity of traffic victims and to explore the impact of these factors on injury severity. A random parameter approach offers methodological flexibility to capture individual-specific heterogeneity. Additionally, to understand the importance of using a reliable injury severity scale, we compared MAIS with length of hospital stay (LHS), a classification used by several countries, including Portugal, to officially report injury severity. To do so, the same statistical technique was applied using the same variables to analyze their impact on the injury severity classified according to LHS.

RESULTS

This study showed the impact of variables, such as the presence of blood alcohol, the use of protection devices, the type of crash, and the site characteristics, on the injury severity classified according to the MAIS score. Additionally, the sex and age of the victims were analyzed as risk factors, showing that elderly and male road users are highly associated with MAIS 3+ injuries. The comparison between the marginal effects of the variables estimated by the MAIS and LHS models showed significant differences. In addition to the differences in the magnitude of impact of each variable, we found that the impact of the road environment variable was dependent on the injury severity classification.

CONCLUSIONS

The differences in the effects of risk factors between the classifications highlight the importance of using a reliable classification of injury severity. Additionally, the relationship between LHS and MAIS levels is quite different among countries, supporting the previous conclusion that bias is expected in the assessment of risk factors if an injury severity classification other than MAIS is used.

Alcohol consumption for simulated driving performance: A systematic review

PURPOSE

Alcohol consumption can lead to risky driving and increase the frequency of traffic accidents, injuries and mortalities. The main purpose of our study was to compare simulated driving performance between two groups of drivers, one consumed alcohol and the other not consumed, using a systematic review.

METHODS

In this systematic review, electronic resources and databases including Medline via Ovid SP, EMBASE via Ovid SP, PsycINFO via Ovid SP, PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (CINHAL) via EBSCOhost were comprehensively and systematically searched. The randomized controlled clinical trials that compared simulated driving performance between two groups of drivers, one consumed alcohol and the other not consumed, were included. Lane position standard deviation (LPSD), mean of lane position deviation (MLPD), speed, mean of speed deviation (MSD), standard deviation of speed deviation (SDSD), number of accidents (NA) and line crossing (LC) were considered as the main parameters evaluating outcomes. After title and abstract screening, the articles were enrolled for data extraction and they were evaluated for risk of biases.

RESULTS

Thirteen papers were included in our qualitative synthesis. All included papers were classified as high risk of biases. Alcohol consumption mostly deteriorated the following performance outcomes in descending order: SDSD, LPSD, speed, MLPD, LC and NA. Our systematic review had troublesome heterogeneity.

CONCLUSION

Alcohol consumption may decrease simulated driving performance in alcohol consumed people compared with non-alcohol consumed people via changes in SDSD, LPSD, speed, MLPD, LC and NA. More well-designed randomized controlled clinical trials are recommended.

Effects of acute alcohol consumption on measures of simulated driving: A systematic review and meta-analysis

Driving simulators are used in a wide range of research settings to help develop an understanding of driver behavior in complex environments. Acute alcohol impairment is an important research topic for traffic safety and a large number of studies have indicated levels of simulated driving impairment imposed by alcohol across a range of performance outcome variables. The aim of the present study was to examine the impact of acute alcohol consumption on simulated driving performance by conducting a systematic review and meta-analysis of the available evidence. The online databases PubMed (MEDLINE), Web of Science (via Thomas Reuters) and Scopus were searched to identify studies that measured simulated car driving performance under control ('no alcohol' or 'placebo alcohol' ingestion) and intervention (acute alcohol ingestion) conditions, using repeated-measures experimental designs. Primary research outcomes were standard deviation of lane position (SDLP) and standard deviation of speed (SDSP); (total number of lane crossings (LC) and average speed (Speed) were secondary research outcomes). Meta-analytic procedures were used to quantify the effect of acute alcohol consumption on vehicle control, and to determine the influence of methodological variables (i.e. the duration of the simulated driving task, the limb of the BAC curve (ascending vs. descending) and the type of driving simulator employed (i.e. car vs. PC-based)) on the magnitude of the performance change due to alcohol consumption. 423 records were screened, and 50 repeated-measures trials (n=962 participants, 62% male) derived from 17 original publications were reviewed. 37 trials (n=721 participants) used a 'placebo alcohol' comparator to determine the effect of alcohol consumption on SDLP (32/37) and SDSP (22/37). Alcohol consumption significantly increased SDLP by 4.0±0.5cm (95% CI: 3.0, 5.1) and SDSP by 0.38±0.10km⋅h^-1 (95% CI: 0.19, 0.57). Regression analyses indicate BAC (p=0.004) and driving simulator platform (p<0.001) influence the magnitude of the SDLP change, such that higher BAC levels and the use of PC-based driving simulators were associated with larger performance decrements (R²=0.80). The limb of the BAC curve and the duration of the driving task did not significantly alter the magnitude of the performance change. Eleven trials (n=205 participants) used a 'no alcohol' comparator to measure the effect of alcohol consumption on SDLP (10/11); few trials assessed SDSP (3/11). Alcohol consumption resulted in a small significant increase in SDLP under these conditions (standardized difference in means=0.23, 95% CI: 0.06, 0.39). These results demonstrate that lateral (SDLP and LC) and longitudinal (SDSP) vehicle control measures in a driving simulator are impaired with acute alcohol consumption. However, SDLP appears to be a more sensitive indicator of driving impairment than other driving performance variables and the results of the present study support its use as a performance outcome when examining alcohol-induced simulated driving impairment.

A systematic review of the evidence for acute tolerance to alcohol - the "Mellanby effect"

OBJECTIVE

To review the evidence for "the Mellanby effect", that is, whether the response to a given blood alcohol concentration (BAC) is more marked when BAC is rising than at the same concentration when BAC is falling.

METHODS

We systematically searched the databases EMBASE, Medline, and Scopus up to and including December 2016 using text words "tolerance", "ascending", "descending" or "Mellanby" with Medline term "exp *alcohol/" or "exp *drinking behavior/" or equivalent. Articles were identified for further examination by title or abstract; full text articles were retained for analysis if they dealt with acute (within dose) alcohol tolerance in human subjects and provided quantitative data on both the ascending and descending parts of the BAC-time curve. Reference lists of identified works were scanned for other potentially relevant material. We extracted and analyzed data on the subjective and objective assessment of alcohol effects.

RESULTS

We identified and screened 386 unique articles, of which 127 full-text articles were assessed; one provided no qualitative results, 62 involved no human study, 25 did not consider acute tolerance within dose, and 13 failed to provide data on both ascending and descending BAC. We extracted data from the 26 remaining articles. The studies were highly heterogeneous. Most were small, examining a total of 770 subjects, of whom 564 received alcohol and were analyzed in groups of median size 10 (range 5-38), sometimes subdivided on the basis of drinking or family history. Subjects were often young white men. Doses of alcohol and rates of administration differed. Performance was assessed by at least 26 different methods, some of which measured many variables. We examined only results of studies which compared results for a given alcohol concentration (C) measured on the ascending limb (C_up) and the descending limb (C_down) of the BAC-time curve, whether in paired or parallel-group studies. When subjects were given alcohol in more than one session, we considered results from the first session only. Rating at C_down was better than at C_up for some measures, as expected if the Mellanby effect were operating. For example, subjects rated themselves less intoxicated on the descending limb than at the same concentration on the ascending limb in 12/13 trials including 229 subjects that gave statistically significant results. In 9 trials with a total of 139 subjects, mean difference could be calculated; weighted for study size, it was 29% [range 24-74%]. Willingness to drive was significantly greater in 4 of 6 studies including a total of 105 subjects; weighted mean difference increased by 207% [range 79-300%]. By contrast, measure of driving ability in three groups of a total of 200 trials in 57 subjects showed worse performance by a weighted mean of 96% [range 3-566%]. In three trials that tested inhibitory control (cued go or no-go response times), weighted mean performance was 30% [range 14-65%] worse on the descending limb.

CONCLUSIONS

The "Mellanby effect" has been demonstrated for subjective intoxication and willingness to drive, both of which are more affected at a stated ethanol concentration when BAC is rising than at the same concentration when BAC is falling. By contrast, objective measures of skills necessary for safe driving, such as response to inhibitory cues and skills measured on driving simulators, were generally worse on the descending part of the BAC-time curve for the same BAC.

Effect of chronic opioid therapy on actual driving performance in non-cancer pain patients

RATIONALE

Chronic non-cancer pain (CNCP) is a major health problem. Patients are increasingly treated with chronic opioid therapy (COT). Several laboratory studies have demonstrated that long-term use of opioids does not generally impair driving related skills. But there is still a lack of studies investigating on-the-road driving performance in actual traffic.

OBJECTIVES

The present study assessed the impact of COT on road-tracking and car-following performance in CNCP patients.

METHODS

Twenty CNCP patients, long-term treated with stable doses of opioid analgesics, and 19 healthy controls conducted standardized on-the-road driving tests in normal traffic. Performance of controls with a blood alcohol concentration (BAC) of 0.5 g/L was used as a reference to define clinically relevant changes in driving performance.

RESULTS

Standard Deviation of Lateral Position (SDLP), a measure of road-tracking control, was 2.57 cm greater in CNCP patients than in sober controls. This difference failed to reach statistical significance in a superiority test. Equivalence testing indicated that the 95% CI around the mean SDLP change was equivalent to the SDLP change seen in controls with a BAC of 0.5 g/L and did not include zero. When corrected for age differences between groups the 95% CI widened to include both the alcohol reference criterion and zero. No difference was found in car-following performance.

CONCLUSIONS

Driving performance of CNCP patients did not significantly differ from that of controls due to large inter-individual variations. Hence in clinical practice determination of fitness to drive of CNCP patients who receive opioid treatments should be based on an individual assessment.

Using alcohol intoxication goggles (Fatal Vision® goggles) to detect alcohol related impairment in simulated driving

OBJECTIVE

Fatal vision goggles (FVGs) are image-distorting equipment used within driver education programs to simulate alcohol-related impairment. However, there is no empirical evidence comparing the behavioral effects associated with wearing FVGs to alcohol intoxication. The purpose of this study was to determine the validity of FVGs in producing alcohol-related impairment in simulated driving.

METHODS

Twenty-two healthy males (age: 23 ± 3 years, mean ± SD) participated in a placebo-controlled crossover design study involving 4 experimental trials. In each trial, participants completed a baseline level simulated driving task followed by an experimental driving task, involving one of 4 treatments: (1) a dose of alcohol designed to elicit 0.080% breath alcohol concentration (BrAC; AB), (2) an alcohol placebo beverage (PB), (3) FVG (estimated % blood alcohol concentration [BAC] 0.070-0.100+), and (4) placebo goggles (PGs). The driving tasks included 3 separate scenarios lasting ∼5 min each; these were a simple driving scenario, a complex driving scenario, and a hazard perception driving scenario. Selected lateral control parameters (standard deviation of lane position [SDLP]; total number of lane crossings [LCs]) and longitudinal control parameters (average speed; standard deviation of speed [SDSP]; distance headway; minimum distance headway) were monitored during the simple and complex driving scenarios. Latency to 2 different stimuli (choice reaction time [CRT]) was tested in the hazard perception driving scenario. Subjective ratings of mood and attitudes toward driving were also provided during each of the trials.

RESULTS

Neither placebo treatment influenced simulated driving performance. Mean BrAC was 0.060 ± 0.010% at the time of driving on the AB trial. Lateral control: In the simple driving scenario, SDLP and LC were not affected under any of the experimental treatments. However, in the complex driving scenario, significantly greater SDLP was observed on both the FVG and AB trials compared to their respective baseline drives. LC increased significantly from baseline on the AB trial only. Longitudinal control: Speed was not affected by any of the experimental treatments; however, SDSP increased significantly from baseline on the FVG trial. A significant reduction in distance headway and minimum distance headway was detected on the FVG trial compared to baseline. Hazard perception: Neither AB nor FVG trials were influential on CRT. Subjective mood ratings were significantly altered on the AB and FVG trials compared to baseline and placebo conditions. Participants reported reduced willingness and ability to drive under the active treatments (AB and FVG) than the placebo treatments (PB and PG).

CONCLUSIONS

FVGs may have some utility in replicating alcohol-related impairment on specific driving performance measurements. Hence, the equipment may offer an alternative approach to researching the impact of alcohol intoxication on simulated driving performance among populations where the provision of alcohol would otherwise be unethical (e.g., prelicensed drivers).

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.

Biomolecules and Biomarkers Used in Diagnosis of Alcohol Drinking and in Monitoring Therapeutic Interventions

BACKGROUND

The quantitative, measurable detection of drinking is important for the successful treatment of alcohol misuse in transplantation of patients with alcohol disorders, people living with human immunodeficiency virus that need to adhere to medication, and special occupational hazard offenders, many of whom continually deny drinking. Their initial misconduct usually leads to medical problems associated with drinking, impulsive social behavior, and drunk driving. The accurate identification of alcohol consumption via biochemical tests contributes significantly to the monitoring of drinking behavior.

METHODS

A systematic review of the current methods used to measure biomarkers of alcohol consumption was conducted using PubMed and Google Scholar databases (2010-2015). The names of the tests have been identified. The methods and publications that correlate between the social instruments and the biochemical tests were further investigated. There is a clear need for assays standardization to ensure the use of these biochemical tests as routine biomarkers.

FINDINGS

Alcohol ingestion can be measured using a breath test. Because alcohol is rapidly eliminated from the circulation, the time for detection by this analysis is in the range of hours. Alcohol consumption can alternatively be detected by direct measurement of ethanol concentration in blood or urine. Several markers have been proposed to extend the interval and sensitivities of detection, including ethyl glucuronide and ethyl sulfate in urine, phosphatidylethanol in blood, and ethyl glucuronide and fatty acid ethyl esters in hair, among others. Moreover, there is a need to correlate the indirect biomarker carbohydrate deficient transferrin, which reflects longer lasting consumption of higher amounts of alcohol, with serum γ-glutamyl transpeptidase, another long term indirect biomarker that is routinely used and standardized in laboratory medicine.

Effects of methadone plus alcohol on cognitive performance in methadone-maintained volunteers

BACKGROUND

Methadone maintenance patients (MMP) often abuse other drugs, including alcohol. The combined use of methadone and alcohol could impair performance and daily functioning.

OBJECTIVE

To examine the effects of methadone in combination with alcohol, as well as acute increases in methadone, on performance outcomes.

METHODS

This double-blind, double-dummy, crossover study included eight opioid-dependent participants stabilized on methadone. Participants completed six inpatient sessions corresponding to methadone (100% or 150% of daily dose) and beverage (placebo, 0.25 or 0.50 g/kg alcohol). Performance tasks were completed before and after drug administration. Area under the time-course values were analyzed by a 2 (methadone dose) by 3 (alcohol dose) repeated measures analysis of variance.

RESULTS

Main effects of methadone were observed for two attention outcomes, suggesting reduced accuracy and slowed responding at an elevated methadone dose. In addition, main effects of alcohol were observed for episodic memory (false alarms and response bias) suggesting more impulsive responding as alcohol dose increased. No robust interactions of methadone and alcohol were observed for any outcome.

CONCLUSIONS

Study findings indicate that an acute increase in methadone (150%) and a moderate dose of alcohol (2-3 drinks) can impair distinct aspects of performance, although no significant interactive effect between methadone and alcohol was found. Future studies with larger sample sizes, larger doses, and more clinically informative tasks could expand on the present findings and further explore the cognitive consequences of concurrent opioid and alcohol use.

Driving while drinking: performance impairments resulting from social drinking

Previous research has shown that the effects of alcohol on drivers' performance can differ depending on whether blood alcohol concentrations are increasing or decreasing. The present research used a more ecologically representative alcohol consumption protocol in order to determine whether the same pattern of driver impairment would occur when drinking occurred in social groups over a longer period of time. Forty-four participants were assigned to one of two alcohol dose conditions or a placebo control group and consumed alcohol in groups of three (typically one participant from each condition) such that they gradually reached their target BAC (.05 or .08) and maintained it for 1 h. The participants completed a series of cognitive tests (Cogstate test battery) and a simulated driving task (driver attention inhibition and reaction test) over the course of their intoxication curve (approximately 4 h). The results showed strong placebo effects on ratings of subjective intoxication. Driving and cognitive performance both showed dose-dependent alcohol impairment, and some measures displayed acute protracted error. The findings provide strong evidence of expectancy effects in contributing to self-perceptions of intoxication.