Effects of alcohol on risk-taking during simulated driving

Effects of alcohol intoxication on driving performance, confidence in driving ability, and psychomotor function: a randomized, double-blind, placebo-controlled study

RATIONALE

Alcohol-induced driving impairment can occur with any departure from a zero-blood alcohol concentration (BAC). Because intoxication is characterised by impaired judgement, drivers under the influence of alcohol may overestimate their capacity to safely operate a vehicle.

OBJECTIVES

This study examined the effects of alcohol on driving performance, four-choice reaction time (FCRT), and self-rated confidence in driving ability. It specifically focused on alcohol doses equal to commonly enforced legal BAC limits (i.e. 0.05% and 0.08%).

METHODS

A randomized, double-blind, placebo-controlled design was utilised. Seventeen participants were tested in three conditions: placebo and two alcohol conditions aiming for BACs of 0.05% and 0.08%. Participants underwent a baseline FCRT task and a 1-h simulated highway driving task before completing another FCRT task and rated their confidence in their driving ability.

RESULTS

The high and low alcohol dose conditions resulted in a mean BAC of 0.07%, and 0.04%, respectively (n = 17). The high BAC treatment significantly increased standard deviation of lateral position (SDLP) by 4.06 ± 5.21 cm and standard deviation of speed (SDS) by 0.69 ± 0.17 km/h relative to placebo, while confidence in driving ability remained unchanged across treatments. FCRT performance was impaired by the high BAC treatment (all < 0.01), but there we no significant differences between placebo and low BAC conditions.

CONCLUSIONS

The findings of this study show that driving performance and associated psychomotor functioning become significantly impaired below legally permissible driving limits in some jurisdictions. We identified a dissociation between driving performance and subjective awareness of impairment. Despite a significantly diminished driving ability at 0.07% BAC, drivers were unaware of their impairment.

Mechanisms of cannabis impairment: Implications for modeling driving performance

Past research on cannabis has been limited in scope to THC potencies lower than legally available and efforts to integrate the effects into models of driving performance have not been attempted to date. The purpose of this systematic review is to understand the implications for modeling driving performance and describe future research needs. The risk of motor vehicle crashes increases 2-fold after smoking marijuana. Driving during acute cannabis intoxication impairs concentration, reaction time, along with a variety of other necessary driving-related skills. Changes to legislation in North America and abroad have led to an increase in cannabis' popularity. This has given rise to more potent strains, with higher THC concentrations than ever before. There is also rising usage of novel ingestion methods other than smoking, such as oral cannabis products (e.g., brownies, infused drinks, candies), vaping, and topicals. The PRISMA guidelines were followed to perform a systematic search of the PubMed database for peer-reviewed literature. Search terms were combined with keywords for driving performance: driving, performance, impairment. Grey literature was also reviewed, including congressional reports, committee reports, and roadside surveys. There is a large discrepancy between the types of cannabis products sold and what is researched. Almost all studies that used inhalation as the mode of ingestion with cannabis that is around 6% THC. This pales in comparison to the more potent strains being sold today which can exceed 20%. Which is to say nothing of extracts, which can contain 60% or more THC. Experimental protocol is another gap in research that needs to be filled. Methodologies that involve naturalistic (real world) driving environments, smoked rather than vaporized cannabis, and non-lab certified products introduce uncontrollable variables. When considering the available literature and the implications of modeling the impacts of cannabis on driving performance, two critical areas emerge that require additional research: The first is the role of cannabis potency. Second is the route of administration. Does the lower peak THC level result in smaller impacts on performance? How long does potential impairment last along the longer time-course associated with different pharmacokinetic profiles. It is critical for modeling efforts to understand the answers to these questions, accurately model the effects on driver performance, and by extension understand the risk to the public.

DUI offenders display reduced perception of intoxication and heightened impulsive choice in response to alcohol

Driving under the influence (DUI) of alcohol continues to be a major contributor in traffic fatalities. There is growing evidence for heightened trait impulsivity in DUI offenders, but little is known about how impulsivity could interact with alcohol intoxication in a manner that would increase the likelihood of driving while intoxicated. This placebo-controlled study examined the acute effects of 0.65g/kg alcohol on 2 facets of impulsivity (impulsive choice and response inhibition), simulated risky driving behavior, and subjective intoxication in a group of 20 DUI offenders and 20 control drivers with no history of DUI. It was predicted that compared with controls, DUI offenders would self-report greater impulsivity, and display greater impulsive choice and driver risk taking, particularly in response to alcohol. Results showed that alcohol impaired drivers' inhibitory control and increased their impulsive choice behavior and risky driving behavior. Alcohol selectively increased impulsive choice of DUI offenders, as control drivers showed no alcohol-induced increase in their impulsive choices. Results also showed that, compared with controls, offenders reported feeling less intoxicated and were more willing to drive after drinking. Laboratory studies are beginning to show that DUI offenders differ from nonoffenders in their acute responses to alcohol. This study identified two alcohol response characteristics of DUI offenders that indicate their lack of risk awareness during intoxication: heightened impulsivity and reduced subjective intoxication. Strategies and treatments to alter these response characteristics in DUI offenders could enhance their risk awareness during the intoxicated state and possibly reduce risk of DUI recidivism. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Identifying the Population Sources of Alcohol Impaired Driving: An Assessment of Context Specific Drinking Risks

OBJECTIVE

High-risk drinkers who drink in high-risk contexts like bars are recognized as a primary source of alcohol-impaired drivers and motor vehicle crashes within communities. We assess the contributions of drinking in other contexts to these outcomes.

METHOD

Self-report survey data from 8,553 adults in 50 California cities were used to estimate rates of driving after drinking (DAD; driving within 4 hours of drinking any alcohol) and a measure of alcohol-impaired driving (AID; driving when having had "too much" to safely drive home) associated with drinking in bars, homes, restaurants, parties, and other contexts.

RESULTS

Frequent drinking (b = .0588, z = 2.17, p = .030) and drinking outside the home, χ²(4) = 74.46, p < .001, at bars (b = .1418, z = 1.97, p = .049), and at restaurants (b = .2694, z = 5.60, p < .001) were related to greater DAD; lower risks were associated with drinking at home (b = -.0607, z = -2.16, p = .031). AID frequency was directly proportional to DAD (b = .0863, z = 8.43, p < .001) with no differences observed across contexts. Within a community of 100,000 persons over 6 months, 879 AID events were attributed to drinking at 102 restaurants and 726 AID events to drinking at 15 bars.

CONCLUSIONS

Drinking at bars and restaurants contributes about equally to DAD and AID, with AID events concentrated in small populations that frequent relatively few bars and broadly distributed across large populations that frequent many restaurants. High frequencies of drinking at home were also associated with surprisingly large numbers of DAD and AID events. Observed differences between individual and community risks for DAD and AID must be addressed in place-based community prevention programs.

Seat belt use among patients in motor vehicle collisions: Clinical and demographic factors

OBJECTIVE

Proper use of automobile seat belt in a motor vehicle crash is associated with reduced morbidity and mortality, shorter hospital stays, reduced resource utilization, and fewer missed work days. Seatbelt compliance nationwide is 86%. This study was undertaken to identify factors associated with noncompliance with seatbelt use among admitted patients following a motor vehicle crash.

METHODS

This study was a retrospective analysis of motor vehicle crashes at an Urban Level 1 Trauma Center. Eligible subjects included patients age 18 and over, who were admitted by the Trauma Service following a motor vehicle crash from January to December 2017.

RESULTS

Among 766 participants, the overall rate of seatbelt noncompliance was 32% (N = 245). Some participants met the legal limit of intoxication (80 mg/dl) (N = 119 patients; 22%). Drug use was high among this population, including THC (30%), opiates (29%), benzodiazepines (24%), cocaine (10%), and methamphetamine (10%). Patients who did not wear seat belts were more likely to be male (62.4% no seat belt vs. 51.8% seat belt), intoxicated (30.5% vs. 17.0%), screen positive for cocaine (18.2% vs. 4.7%), THC (37.7% vs. 24.2%), and methamphetamine (15.6% vs. 5.9%). We did not detect significant differences by seat belt use with respect to ethnicity, mode of arrival, day of week, opiate use, or benzodiazepine use.

CONCLUSIONS

In this study, 32% of patients in motor vehicle crashes were not compliant with seat belt use. Noncompliance with seat belt use was higher among patients who were male, younger age, intoxicated, or who had positive screens for cocaine, THC, or methamphetamine.

The role of restraint omission in alcohol-related traffic fatalities

BACKGROUND AND AIMS

Fatal traffic accidents affect thousands of people in the US alone every year. Alcohol consumption has been identified as a strong predictor of traffic fatalities. This result is hardly surprising as drivers who decide to consume alcohol and then drive are more likely to exhibit poor driving performance. In this paper, I argue that alcohol consumption can lead to traffic fatalities by increasing restraint omission.

METHODS

I analyzed individual-level data about victims (n=488,829) of fatal traffic accidents that occurred in the US between January 1, 1999 and December 31, 2015 from the Fatality Analysis Reporting System of the National Highway Traffic and Safety Administration.

RESULTS

There is a strong relationship between alcohol consumption and restraint use. Both vehicle drivers and occupants are far less likely to be restrained when inebriated. Additional analyses show that part of the effect of alcohol consumption on traffic fatalities can be attributed to restraint omission.

CONCLUSIONS

There is a significant relationship between alcohol consumption and restraint omission for both drivers and occupants of vehicles that were involved in fatal traffic accidents in the US between January 1999 and December 2015. Past public health campaigns have focused on preventing traffic fatalities by persuading drivers to refrain from getting behind the wheel after consuming alcohol. My data suggest that public health campaigns should inform both drivers and occupants of vehicles about the relationship between alcohol and restraint omission in order to minimize future casualties.

Drinking and driving behavior at stop signs and red lights

Alcohol is one of the principal risk factors for motor vehicle crashes. One factor that contributes to vehicle crashes is noncompliance with stop signs and red lights. The present experiment investigated the effects of alcohol and drinking patterns on driving behavior at stop signs and red lights. 28 participants participated in drinking and simulated driving sessions during which they received a moderate dose of alcohol (0.08% BAC) or a placebo. Simulated driving tasks measured participants' driving performance at stop signs and red lights in response to each dose. Results suggested that alcohol impaired the driver control of speed and direction and prolonged their simple and complex reaction time, which were exhibited by impaired speed and lateral control, longer reaction time when the lights turned yellow, and lower deceleration towards stop signs and red lights. Visual degradation may also occur under alcohol intake. It was also suggested that alcohol impaired non-binge drinkers more severely. To be specific, higher acceleration was observed in impaired non-binge drinkers.

Laboratory analysis of risky driving at 0.05% and 0.08% blood alcohol concentration

BACKGROUND

The public health costs associated with alcohol-related traffic crashes are a continuing problem for society. One harm reduction strategy has been to employ per se limits for blood alcohol concentrations (BACs) at which drivers can legally operate motor vehicles. This limit is currently 0.08% in all 50 US states. Recently, the National Transportation Safety Board proposed lowering the legal limit to 0.05% (NTSB, 2013). While research has well-validated the ability of alcohol to impair driving performance and heighten crash-risk at these BACs, relatively little is known about the degree to which alcohol might increase drivers' risk-taking.

METHODS

Risk-taking was examined in 20 healthy adults who were each tested in a driving simulator following placebo and two doses of alcohol calculated to yield peak BACs of 0.08% and 0.05%, the respective current and proposed BAC limits. The drive test emphasized risk-taking by placing participants in a multiple-lane, high-traffic environment. The primary measure was how close drivers maneuvered relative to other vehicles on the road (i.e., time-to-collision, TTC).

RESULTS

Alcohol increased risk-taking by decreasing drivers' TTC at the 0.08% target BAC relative to placebo. Moreover, risk-taking at the 0.05% target was less than risk-taking at 0.08% target BAC.

CONCLUSIONS

These findings provide evidence that reducing the legal BAC limit in the USA to 0.05% would decrease risk-taking among drivers. A clearer understanding of the dose-response relationship between various aspects of driving behaviors, such as drivers' accepted level of risk while driving, is an important step to improving traffic safety.

A simulation study of the effects of alcohol on driving performance in a Chinese population

Driving under the influence of alcohol (DUIA) is a significant factor contributing to road traffic crashes, injuries, and fatalities. Although the effects of alcohol on driving performance are widely acknowledged, studies of the effects of alcohol impairment on driving performance and particularly on the control system of Chinese adults are rare. This study attempts to evaluate the effects of alcohol on the driving performance of Chinese adults using a driving simulator.

METHOD

A double-blind experimental study was conducted to evaluate the effects of alcohol impairment on the driving performance of 52 Chinese participants using a driving simulator. A series of simulated driving tests covering two driving modules, including emergency braking (EB) and following braking (FB), at 50km/h and 80km/h were performed. Linear mixed models were established to evaluate driving performance in terms of braking reaction time (BRT), the standard deviation of lateral position (SD-LANE), and the standard deviation of speed (SD-SPEED).

RESULTS

Driving performance in terms of BRT and SD-LANE was highly correlated with the level of alcohol consumption, with a one-unit increase in breath alcohol concentration (BrAC) degrading BRT and SD-LANE by 0.3% and 0.2%, respectively. Frequent drinkers generally reacted faster in their BRT than less-frequent drinkers and non-drinkers by 10.2% and 30.6%, respectively. Moreover, alcohol impairment had varying effects on certain aspects of the human control system, and automatic action was less likely to be affected than voluntary action from a psychological viewpoint.

CONCLUSION

The findings should be useful for planning and developing effective measures to combat drink driving in Chinese communities.

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.

Personality, Executive Control, and Neurobiological Characteristics Associated with Different Forms of Risky Driving

Background

Road crashes represent a huge burden on global health. Some drivers are prone to repeated episodes of risky driving (RD) and are over-represented in crashes and related morbidity. However, their characteristics are heterogeneous, hampering development of targeted intervention strategies. This study hypothesized that distinct personality, cognitive, and neurobiological processes are associated with the type of RD behaviours these drivers predominantly engage in.

Methods

Four age-matched groups of adult (19–39 years) males were recruited: 1) driving while impaired recidivists (DWI, n = 36); 2) non-alcohol reckless drivers (SPEED, n = 28); 3) drivers with a mixed RD profile (MIXED, n = 27); and 4) low-risk control drivers (CTL, n = 47). Their sociodemographic, criminal history, driving behaviour (by questionnaire and simulation performance), personality (Big Five traits, impulsivity, reward sensitivity), cognitive (disinhibition, decision making, behavioural risk taking), and neurobiological (cortisol stress response) characteristics were gathered and contrasted.

Results

Compared to controls, group SPEED showed greater sensation seeking, disinhibition, disadvantageous decision making, and risk taking. Group MIXED exhibited more substance misuse, and antisocial, sensation seeking and reward sensitive personality features. Group DWI showed greater disinhibition and more severe alcohol misuse, and compared to the other RD groups, the lowest level of risk taking when sober. All RD groups exhibited less cortisol increase in response to stress compared to controls.

Discussion

Each RD group exhibited a distinct personality and cognitive profile, which was consistent with stimulation seeking in group SPEED, fearlessness in group MIXED, and poor behavioural regulation associated with alcohol in group DWI. As these group differences were uniformly accompanied by blunted cortisol stress responses, they may reflect the disparate behavioural consequences of dysregulation of the stress system. In sum, RD preference appears to be a useful marker for clarifying explanatory pathways to risky driving, and for research into developing more personalized prevention efforts.

Acute alcohol exposure impairs neural representation of visual motion speed in the visual cortex area posteromedial lateral suprasylvian cortex of cats

BACKGROUND

Psychophysical and behavioral studies have demonstrated that perception of motion can be impaired by acute alcohol exposure. The neural activities of posteromedial lateral suprasylvian cortex (PMLS) of cats are directly linked to the perception of visual motion speed. To date, there have been no studies on the effects of acute alcohol exposure in vivo upon the representation of speed in PMLS neurons.

METHODS

Alcohol was administered intravenously as a 20% (v/v) saline solution via a syringe at a dose levels of 0.5, 1, or 2 g/kg to generate a series of blood alcohol concentrations. Using extracellular single-unit recording technique, we recorded the speed-tuning properties of PMLS neurons that responded to random-dot patterns before and after alcohol administration, and simultaneously monitored the concentration of ethanol by detecting the breath alcohol concentration using a breath analyzer.

RESULTS

After acute alcohol treatment, PMLS cells preferred lower speeds. A broadened speed-tuning bandwidth of PMLS cells was also observed after acute alcohol administration. Additionally, response modulation and discriminative capacity for speed of visual motion in the PMLS cells were significantly impaired after acute alcohol exposure. Concurrently, PMLS cells after acute alcohol exposure showed decreased spontaneous activity, peak responses, and signal-to-noise ratios.

CONCLUSIONS

There is a significant functional degradation in the neural representation of visual motion speed in PMLS of cats after acute alcohol exposure. These neural changes may contribute to the alcohol-related deficits in visual motion perception observed in behavioral studies.

Self-reported risk-taking behavior during matched-frequency sessions of alcohol versus combined alcohol and energy drinks consumption: does co-ingestion increase risk-taking?

BACKGROUND

Emerging evidence indicates that consumers of alcohol mixed with energy drink (AmED) self-report lower odds of risk-taking after consuming AmED versus alcohol alone. However, these studies have been criticized for failing to control for relative frequency of AmED versus alcohol-only consumption sessions. These studies also do not account for quantity of consumption and general alcohol-related risk-taking propensity. The aims of the present study were to (i) compare rates of risk-taking in AmED versus alcohol sessions among consumers with matched frequency of use and (ii) identify consumption and person characteristics associated with risk-taking behavior in AmED sessions.

METHODS

Data were extracted from 2 Australian community samples and 1 New Zealand community sample of AmED consumers (n = 1,291). One-fifth (21%; n = 273) reported matched frequency of AmED and alcohol use.

RESULTS

The majority (55%) of matched-frequency participants consumed AmED and alcohol monthly or less. The matched-frequency sample reported significantly lower odds of engaging in 18 of 25 assessed risk behaviors in AmED versus alcohol sessions. Similar rates of engagement were evident across session type for the remaining behaviors, the majority of which were low prevalence (reported by <15%). Regression modeling indicated that risk-taking in AmED sessions was primarily associated with risk-taking in alcohol sessions, with increased average energy drink (ED) intake associated with certain risk behaviors (e.g., being physically hurt, not using contraception, and driving while over the legal alcohol limit).

CONCLUSIONS

Bivariate analyses from a matched-frequency sample align with past research showing lower odds of risk-taking behavior after AmED versus alcohol consumption for the same individuals. Multivariate analyses showed that risk-taking in alcohol sessions had the strongest association with risk-taking in AmED sessions. However, hypotheses of increased risk-taking post-AmED consumption were partly supported: Greater ED intake was associated with increased likelihood of specific behaviors, including drink-driving, sexual behavior, and aggressive behaviors in the matched-frequency sample after controlling for alcohol intake and risk-taking in alcohol sessions. These findings highlight the need to consider both personal characteristics and beverage effects in harm reduction strategies for AmED consumers.

Testing a social ecological model of alcohol use: the California 50-city study

BACKGROUND AND AIMS

Social ecological theories suggest that greater community alcohol availability and individual drinker characteristics should jointly affect drinking patterns and the use of drinking contexts. We assessed relationships of demographic and personality characteristics of individual drinkers and environmental characteristics at the city-level to measures of drinking patterns and use of drinking contexts.

DESIGN

Multi-level statistical analyses of archival and survey data from 50 cities in California, USA.

SETTINGS

An ecological sample of 50 geographically distinct cities with populations from 50 000 to 500 000 people.

PARTICIPANTS

General population telephone survey of 8553 adults 18 years of age and older stratified by cities.

MEASUREMENTS

Archival data on city-level alcohol outlet densities were combined with individual survey data identifying community conditions, individual demographic and psychosocial characteristics, frequencies of use of drinking contexts and drinking patterns.

FINDINGS

Greater on-premise outlet densities were related to greater drinking frequencies (b = 2.9671, z = 4.688, P < 0.001) and volumes (b = 0.6274, z = 3.394, P < 0.001) and use of on-premises drinking places (bars, b = 0.3340, z = 2.645, P < 0.006 and restaurants, b = 0.1712, z = 2.770, P = 0.005). Individual demographic and personality characteristics were related to drinking and use of drinking contexts. For example, greater impulsivity was related to greater drinking frequencies (b = 0.2001, z = 2.088, P = 0.023) and logged quantities (b = 0.0151, z = 2.009, P = 0.026) and proportionately more drinking at bars (b = 0.0332, z = 2.016, P = 0.026) and parties (b = 0.1712, z = 2.770, P = 0.004).

CONCLUSION

Community availability of alcohol and individual drinker characteristics appear to act jointly to affect drinking levels and use of drinking contexts. These effects may increase risks related to drinking in some contexts (e.g. bars) much more than others (e.g. at friends' or relatives' homes).

Interactions between age and moderate alcohol effects on simulated driving performance

RATIONALE

There is a substantial body of literature documenting the deleterious effects of both alcohol consumption and age on driving performance. There is, however, limited work examining the interaction of age and acute alcohol consumption.

OBJECTIVES

The current study was conducted to determine if moderate alcohol doses differentially affect the driving performance of older and younger adults.

METHODS

Healthy older (55-70) and younger (25-35) adults were tested during a baseline session and again following consumption of one of three beverages [0.0 % (placebo), 0.04 % or 0.065 % target breath alcohol concentration]. Measures of driving precision and average speed were recorded.

RESULTS

Older adults performed more poorly on precision driving measures and drove more slowly than younger adults at baseline. After controlling for baseline performance, interactions between alcohol and age were observed following beverage consumption on two measures of driving precision with older adults exhibiting greater impairment as a result of alcohol consumption.

CONCLUSIONS

These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance. An investigation of mechanisms accounting for alcohol's effects on driving in older and younger adults is required. Further evaluation using more complex driving environments is needed to assess the real-world implication of this interaction.

A review of alcohol-impaired driving: the role of blood alcohol concentration and complexity of the driving task

The operation of a motor vehicle requires the integrity of sensory, motor, and intellectual faculties. Impairment of these faculties following the consumption of alcohol has been studied extensively through laboratory, closed-course and on-road driving, and epidemiological studies. The scientific literature was reviewed critically, with a focus on low-to-moderate blood alcohol concentrations (BAC ≤ 0.100%), to identify the most reliable determinants of alcohol-impaired driving. Variables such as age, gender, driving skill, and tolerance were shown to have limited impact on impairment. It was concluded the most relevant variables are BAC and complexity of the driving task. The scientific literature provides a high degree of confidence to support the conclusion that a BAC of 0.050% impairs faculties required in the operation of a motor vehicle. Whether impairment is apparent depends upon the complexity of the driving task, which applies to both study design and actual driving.

Alcohol attenuates amygdala-frontal connectivity during processing social signals in heavy social drinkers: a preliminary pharmaco-fMRI study

RATIONALE

Convergent evidence shows that alcohol exerts its effects on social behavior via modulation of amygdala reactivity to affective stimuli. Given that affective processing involves dynamic interactions between the amygdala and the prefrontal cortex (PFC), alcohol's effects are likely to extend beyond regional changes in brain activity to changes that manifest on a broader functional circuit level.

OBJECTIVE

The current study examines alcohol's effects on functional connectivity (i.e., "coupling") between the amygdala and the PFC during the processing of socio-emotional stimuli using functional magnetic resonance imaging (fMRI).

METHODS

In a randomized, double blind, placebo-controlled, within-subjects cross-over design, 12 heavy, social drinkers performed an fMRI task designed to probe amygdala response to socio-emotional stimuli (angry, fearful, and happy faces) following acute ingestion of alcohol or placebo. Functional connectivity between the amygdala and PFC was examined and compared between alcohol and placebo sessions using a conventional generalized psychophysiological interaction (gPPI) analysis.

RESULTS

Relative to placebo, alcohol reduced functional coupling between the amygdala and the right orbitofrontal cortex (OFC) during processing of both angry and fearful faces. Alcohol also reduced functional coupling between the amygdala and left OFC during processing of happy faces.

CONCLUSIONS

These preliminary findings suggest that alcohol's effects on social behavior may be mediated by alternations in functional connectivity between the amygdala and OFC during processing of emotional faces.

A diffusion model decomposition of the effects of alcohol on perceptual decision making

RATIONALE

Even in elementary cognitive tasks, alcohol consumption results in both cognitive and motor impairments (e.g., Schweizer and Vogel-Sprott, Exp Clin Psychopharmacol 16: 240-250, 2008).

OBJECTIVES

The purpose of this study is to quantify the latent psychological processes that underlie the alcohol-induced decrement in observed performance.

METHODS

In a double-blind experiment, we administered three different amounts of alcohol to participants on different days: a placebo dose (0 g/l), a moderate dose (0.5 g/l), and a high dose (1 g/l). Following this, participants performed a "moving dots" perceptual discrimination task. We analyzed the data using the drift diffusion model. Model parameters drift rate, boundary separation, and non-decision time allow a decomposition of the alcohol effect in terms of their respective cognitive components, that is, rate of information processing, response caution, and non-decision processes (e.g., stimulus encoding, motor processes).

RESULTS

We found that alcohol intoxication causes higher mean RTs and lower response accuracies. The diffusion model decomposition showed that alcohol intoxication caused a decrease in drift rate and an increase in non-decision time.

CONCLUSIONS

In a simple perceptual discrimination task, even a moderate dose of alcohol decreased the rate of information processing and negatively affected the non-decision component. However, alcohol consumption left response caution largely intact.

Alcohol effects on simulated driving in frequent and infrequent binge drinkers

OBJECTIVE

Compared with non‐bingers, binge drinkers are more likely to drive while intoxicated. The extent to which binge frequency impacts confidence in driving and subsequent driving impairment is unknown. This study compared the effects of an experimenter‐delivered alcohol binge on subjective impairment and simulated driving ability in female high‐frequency and low‐frequency bingers.

METHODS

Female drinkers were assigned to high‐frequency (n = 30) or low‐frequency (n = 30) binge groups based on their Alcohol Use Questionnaire responses. At 30‐min intervals within a 2‐h period, participants received either a placebo drink (n = 15 per group) or a 0.2 g/kg dose of alcohol (n = 15 per group; cumulative dose 0.8 g/kg). Self‐reported impairment, driving confidence, and simulated driving were then measured.

RESULTS

Self‐reported confidence in driving was significantly lower after alcohol than after placebo in low‐frequency but not highfrequency bingers. Self‐reported impairment and collisions during simulated driving were significantly greater after alcohol than after placebo in both low‐frequency and high‐frequency bingers.

CONCLUSIONS

The impairing effects of a single alcohol binge on driving ability in women are not influenced by binge frequency. However, high binge frequency may be associated with a less cautious approach to post‐binge driving.

The effect of cannabis compared with alcohol on driving

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

Lorazepam dose-dependently decreases risk-taking related activation in limbic areas

RATIONALE

Several studies have examined the role of different neurotransmitter systems in modulating risk-taking behavior.

OBJECTIVE

This investigation was aimed to determine whether the benzodiazepine lorazepam dose-dependently alters risk-taking behavior and underlying neural substrates.

MATERIALS AND METHODS

Fifteen healthy, nonsmoking, individuals (six women, nine men), aged 18-39 years (mean 27.6 +/- 1.4 years) with 12-18 years of education (mean 15.6 +/- 0.3 years) underwent functional magnetic resonance imaging while performing a risk-taking decision-making task.

RESULTS

Our results show that lorazepam did not affect risky behavior at 0.25 and 1 mg, but dose-dependently attenuated activation in (a) the amygdala and medial prefrontal cortex during the response selection phase, and in (b) the bilateral insular cortex and amygdala during the outcome (i.e., rewarded or punished) phase. Furthermore, a lorazepam-induced increase in insular cortex activation was associated with less risky responses.

CONCLUSIONS

Taken together, our findings support the idea that GABAergic modulation in limbic and paralimbic structures is important during both the response selection and outcome phase of risk-taking decision-making.

Effects of prolonged wakefulness combined with alcohol and hands-free cell phone divided attention tasks on simulated driving

Simulated driving ability was assessed following administration of alcohol, at an estimated blood level of 0.05%, and combined prolonged wakefulness, while participants were undertaking divided attention tasks over a hands-free mobile phone. Divided attention tasks were structured to provide a sustained cognitive workload to the subjects. Twenty three young healthy individuals drove 10 km simulated driving under four conditions in a counterbalanced, within-subject design: alcohol, alcohol and 19 h wakefulness, alcohol and 24 h wakefulness, and while sober. Study measures were: simulated driving, self-reported sleepiness, critical flicker fusion threshold (CFFT), Stroop word-colour interference test (Stroop) and simple visual reaction times (SVRT). As expected, subjective sleepiness was highly correlated with both sleep restriction and alcohol consumption. The combination of alcohol and 24 h sustained wakefulness produced the highest driving impairment, significantly beyond the alcohol effect itself. Concurrent alcohol and 19 h wakefulness significantly affected only driving time-to-collision. No significant changes of study measures occurred following alcohol intake in unrestricted sleep conditions. CFFT, SVRT and Stroop results showed a similar trend in the four study conditions. Thus apparently 'safe' blood alcohol levels in combination with prolonged wakefulness resulted in significant driving impairments. In normal sleep conditions alcohol effects on driving were partially counteracted by the concomitant hands-free phone based psychometric tasks.

United States male students who heavily consume alcohol in Mexico are at greater risk of travelers' diarrhea than their female counterparts

BACKGROUND

The relationship between alcohol consumption and travelers' diarrhea has not been well studied.

METHODS

A cohort of US college students (n=171), who attended 2001 or 2002 summer educational sessions in Guadalajara, Mexico, were followed prospectively to examine the frequency of alcohol consumption and the development of travelers' diarrhea.

RESULTS

More male students reported consuming >5 drinks/day of drinking while in Mexico compared to female students (p <.001). Males who consumed >5 drinks/day of drinking while in Mexico were more likely to develop diarrhea than their female counterparts who drank the same amount (79% vs. 46%; p=.035). No association was found between the development of travelers' diarrhea and the consumption of fewer than 5 drinks per day in Mexico. Non-drinkers accounted for only 8% of the population and had a relatively high attack rate of diarrhea (69%).

CONCLUSIONS

This study suggests that males who drink heavily are at high risk for developing travelers' diarrhea and may be a group of people to target for education about the moderation of use of alcohol while traveling. Nondrinkers also deserve further study in larger numbers to confirm an apparently high attack rate of diarrhea and to explore what risk factors might be involved.

Alcohol and cognitive control: implications for regulation of behavior during response conflict

Alcohol intoxication often leads to dysregulated behavior in contexts characterized by conflict between prepotent response tendencies and incompatible alternative responses. Recent research has identified 2 components of an anterior executive attention system that are essential for adaptive behavior when response conflict exists. Event-related potential (ERP) measures of evaluative and regulative cognitive control were collected to determine if impaired executive attention was responsible for observed behavior deficits when intoxicated. Intoxicated participants displayed task performance deficits on incongruent color-naming trials relative to sober controls. Alcohol did not affect P3 magnitude/latency, indicating that timing and integrity of stimulus evaluation remained intact. In contrast, alcohol did reduce frontal components of ERP that index evaluative and regulative cognitive control processes.

Differential effects of alcohol and alcohol expectancy on risk-taking during simulated driving

This study examined the separate and combined effects of alcohol (0.0 or 0.5 g/kg) and alcohol expectancies (none or 2-3 standard drinks) on risk-taking using a simulated-driving lane choice task. In this task, risk-taking was operationalized as choosing a cone-defined lane with a higher relative probability of hitting a cone. When alcohol was received but not expected, the probability of a risky lane choice increased compared with when alcohol was neither expected nor received. However, when subjects both expected and received alcohol, the probability of a risky lane choice was significantly decreased compared with when alcohol was neither expected nor received. These findings suggest that the knowledge of dose received can differentially influence the pharmacological effect of alcohol on decision-making.