The effects of dexamphetamine on simulated driving performance

Rationale The number of road fatalities related to the presence of amphetamines in drivers has been relatively constant over the past 10 years. However, there remains uncertainty as to the extent that these drugs induce driving impairment, and whether any such impairments translate to an increase in road fatalities.Objectives To examine the acute effects of 0.42 mg/kg dexamphetamine on simulated driving performance, and to establish which, if any, simulated driving abilities become impaired following dexamphetamine administration.Methods A repeated-measures, counter-balanced, double-blind, placebo-controlled design was employed. Twenty healthy volunteers completed two treatment conditions—0.42 mg/kg dexamphetamine and placebo. Performance was assessed using a driving simulator task. Blood and saliva samples were obtained prior to the driving tasks and immediately after task completion (120 min and 170 min post-drug administration, respectively).Results Mean dexamphetamine blood concentrations were 83 ng/ml and 98 ng/ml at 120 min and 170 min, respectively. Results indicated a decrease in overall simulated driving ability following dexamphetamine administration during the day-time but not the night-time scenario tasks. Contributing to this performance reduction, incorrect signalling, failing to stop at a red traffic light and slow reaction times were the behaviours most strongly affected by dexamphetamine.Conclusions The decrease in simulated driving ability observed during the day-time driving tasks are consistent with the perceptual narrowing or tunnel vision that is associated with dexamphetamine consumption.     

Effects of alcohol on risk-taking during simulated driving

The effect of alcohol on judgement or conscious risk-taking may increase the likelihood of an automobile accident. This study examined the direct effects of penalty severity and alcohol on risk-taking in a novel simulated-driving lane-choice task. Thirteen male social drinkers received alcohol (0.3 g/kg, 0.5 g/kg, 0.8 g/kg) or placebo during each of four test sessions in a randomized, within subject design. In repeated trials, subjects selected, then drove through a cone-defined lane. Contingent upon performance, points were added (+ 5 for the narrower lane, + 3 for the wider lane) and taken away (- 1, - 3, or - 5 points per hit cone) after each trial. Risk-taking was defined as a selection of the narrower-width lane. The frequency of risk-taking decreased as the penalty increased. The 0.5 g/kg dose, compared to other alcohol doses or placebo, significantly increased risk-taking in the high-risk (5-point penalty) condition. This finding suggests that breath alcohol concentrations within current legal standards can alter a driver's decision-making such that the willingness to enter a high-risk situation is increased.     

Effects of alcohol hangover on simulated highway driving performance

Background

The purpose of this study was to examine the effects of alcohol hangover on simulated highway driving performance.

Methods

Driving performance of forty-two social drinkers was tested the morning following an evening of consuming on average 10.2 (SD?=?4.2) alcoholic drinks (alcohol hangover) and on a control day (no alcohol consumed). Subjects performed a standardized 100-km highway driving test in the STISIM driving simulator. In addition to the standard deviation of lateral position (SDLP; i.e., the weaving of the car), lapses of attention were examined. Self-reported driving quality and driving style were scored, as well as mental effort to perform the test, sleepiness before and after driving, and hangover severity.

Results

Driving performance was significantly impaired during alcohol hangover as expressed by an SDLP increase of +1.9 cm (t _(1,41)?=?2.851, p?=?0.007), increased number of lapses relative to the control day (7.7 versus 5.3 lapses, t _(1,41)?=?2.125, p?=?0.019), and an increased total lapse time (182.7 versus 127.3 s, p?=?0.040). During alcohol hangover, subjects reported their driving quality to be significantly poorer (t _(1,41)?=?4.840, p?=?0.001) and less safe (t _(1,41)?=?5.078, p?=?0.001), wise (t _(1,41)?=?4.061, p?=?0.001), predictable (t _(1,41)?=?3.475, p?=?0.001), and responsible (t _(1,41)?=?4.122, p?=?0.001). Subjects further reported being significantly more tense while driving (t _(1,41)?=?3.280, p?=?0.002), and more effort was needed to perform the driving test (t _(1,41)?=?2.941, p?=?0.001). There was a significant interaction with total sleep time and hangover effects on SDLP and the number of lapses.

Conclusions

In conclusion, driving is significantly impaired during alcohol hangover, as expressed in an elevated SDLP and increased number of lapses. Total sleep time has a significant impact on the magnitude of driving impairment.     

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.     

Cannabis effects on driving longitudinal control with and without alcohol

Although evidence suggests cannabis impairs driving, its driving‐performance effects are not fully characterized. We aimed to establish cannabis’ effects on driving longitudinal control (with and without alcohol, drivers’ most common drug combination) relative to psychoactive ?⁹‐tetrahydrocannabinol (THC) blood concentrations. Current occasional (≥1×/last 3 months, ≤3 days per week) cannabis smokers drank placebo or low‐dose alcohol, and inhaled 500 mg placebo, low (2.9%), or high (6.7%) THC vaporized cannabis over 10 min ad libitum in separate sessions (within‐subject, six conditions). Participants drove (National Advanced Driving Simulator, University of Iowa) simulated drives 0.5–1.3 h post‐inhalation. Blood and breath alcohol samples were collected before (0.17 and 0.42 h) and after (1.4 and 2.3 h) driving. We evaluated the mean speed (relative to limit), standard deviation (SD) of speed, percent time spent >10% above/below the speed limit (percent speed high/percent speed low), longitudinal acceleration, and ability to maintain headway relative to a lead vehicle (headway maintenance) against blood THC and breath alcohol concentrations (BrAC). In N=18 completing drivers, THC was associated with a decreased mean speed, increased percent speed low and increased mean following distance during headway maintenance. BrAC was associated with increased SD speed and increased percent speed high, whereas THC was not. Neither was associated with altered longitudinal acceleration. A less‐than‐additive THC*BrAC interaction was detected in percent speed high (considering only non‐zero data and excluding an outlying drive event), suggesting cannabis mitigated drivers’ tendency to drive faster with alcohol. Cannabis was associated with slower driving and greater headway, suggesting a possible awareness of impairment and attempt to compensate. Copyright © 2016 John Wiley & Sons, Ltd.     

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.     

Effects of viloxazine with and without alcohol on performance tests related to driving in normal volunteers

The effects of single doses of 50 mg of viloxazine, 100 mg of viloxazine, 50 mg of imipramine, and placebo given alone and in combination with alcohol on perceptual-motor performance potentially related to driving were studied in eight normal subjects. The study design permitted testing of visual reaction time, pursuit rotor performance, and depth perception when blood levels of the active drugs and alcohol were at or near peak. Analyses revealed that the effects of alcohol increased visual reaction time and decreased pursuit rotor performance. None of the drugs produced statistically significant changes on any of the measures. None of the effects of the combined drug and alcohol conditions differed significantly from the effects of alcohol alone.     

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.     

Effects of coffee on driving performance during prolonged simulated highway driving

Rationale

Coffee is often consumed to counteract driver sleepiness. There is limited information on the effects of a single low dose of coffee on prolonged highway driving in non-sleep deprived individuals.

Objectives

The aim of this study was to examine the effects of a single cup of coffee (80?mg caffeine) on simulated highway driving performance.

Methods

Non-sleep deprived healthy volunteers (n?=?24) participated in a double-blind, placebo-controlled, crossover study. After 2?h of monotonous highway driving, subjects received caffeinated or decaffeinated coffee during a 15-min break before continuing driving for another 2?h. The primary outcome measure was the standard deviation of lateral position (SDLP), reflecting the weaving of the car. Secondary outcome measures were speed variability, subjective sleepiness, and subjective driving performance.

Results

The results showed that caffeinated coffee significantly reduced SDLP as compared to decaffeinated coffee, both in the first (p?=?0.024) and second hour (p?=?0.019) after the break. Similarly, the standard deviation of speed (p?=?0.024; p?=?0.001), mental effort (p?=?0.003; p?=?0.023), and subjective sleepiness (p?=?0.001; p?=?0.002) were reduced in both the first and second hour after consuming caffeinated coffee. Subjective driving quality was significantly improved in the first hour after consuming caffeinated coffee (p?=?0.004).

Conclusions

These findings demonstrate a positive effect of one cup of caffeinated coffee on driving performance and subjective sleepiness during monotonous simulated highway driving.     

Effects of mefloquine alone and with alcohol on psychomotor and driving performance

Objective: To determine whether mefloquine, a quinoline antimalarial drug, affects psychomotor and actual driving performance when given in a prophylactic regimen, alone or in combination with alcohol. Methods: Forty male and female volunteers were randomly assigned in equal numbers to two groups, and were treated double-blind for one month with mefloquine and placebo. The medication was taken in a 250 mg dose on the evenings of Days 1, 2, 3, 8, 15, 22 and 29. Testing was done on Days 4, 23 and 30, the latter after repeated doses of alcohol sufficient to sustain a blood concentration of about 0.35 mg ⋅ml⁻¹. Two real driving tests were used to measure prolonged (1 h) road tracking and car following performance. Critical Flicker/Fusion Frequency (CFF), critical instability tracking and body sway were also measured in the laboratory. Results: Mefloquine caused no significant impairment in any test at any time relative to placebo. It significantly improved road tracking performance on Day 4. A significant interaction between prior treatment and alcohol was found in the body sway test, as the alcohol-induced change was less after mefloquine than placebo. The sensitivity of the driving test and the CFF test were shown by the significant overall effect of alcohol which did not discriminate between the two prior treatments. Conclusion: Mefloquine did not impair driving performance but rather improved it in the longer test, suggesting that the drug may possess psychostimulating properties. Received: 7 December 1995/Accepted in revised form: 27 February 1996     

Effects of alcohol on automated and controlled driving performances

Rationale

Alcohol is the most frequently detected substance in fatal automobile crashes, but its precise mode of action is not always clear.

Objective

The present study was designed to establish the influence of blood alcohol concentration as a function of the complexity of the scenarios. Road scenarios implying automatic or controlled driving performances were manipulated in order to identify which behavioral parameters were deteriorated.

Method

A single blind counterbalanced experiment was conducted on a driving simulator. Sixteen experienced drivers (25.3?±?2.9 years old, 8 men and 8 women) were tested with 0, 0.3, 0.5, and 0.8 g/l of alcohol. Driving scenarios varied: road tracking, car following, and an urban scenario including events inspired by real accidents. Statistical analyses were performed on driving parameters as a function of alcohol level.

Results

Automated driving parameters such as standard deviation of lateral position measured with the road tracking and car following scenarios were impaired by alcohol, notably with the highest dose. More controlled parameters such as response time to braking and number of crashes when confronted with specific events (urban scenario) were less affected by the alcohol level.

Conclusion

Performance decrement was greater with driving scenarios involving automated processes than with scenarios involving controlled processes.     

Separate and combined effects of marijuana and alcohol on mood,equilibrium and simulated driving

Abstract Rationale . Marijuana and alcohol, when used separately and in combination, contribute to automobile accidents and failed sobriety tests of standing balance. However, the extent to which the drugs have additive effects on both of these measures is unknown. Objectives . This study was designed to compare directly the separate and combined effects of marijuana and alcohol on simulated emergency braking and dynamic posturography. Methods. Twelve healthy subjects who regularly used both marijuana and alcohol completed nine test sessions in a counterbalanced within-subject design. Subjects drank a beverage (0, 0.25, or 0.5 g/kg alcohol) then smoked a cigarette (0, 1.75, or 3.33% THC). Testing began 2 min after smoking and was conducted within the ascending limb of the blood alcohol curve. Results. The 0.5 g/kg alcohol dose significantly increased brake latency without affecting body sway. In contrast, the 3.3% THC dose increased body sway but did not affect brake latency. There were no additive drug effects on mood or behavior. Conclusions . Although field sobriety tests are often used to determine driving impairment, these results suggest that impaired balance following marijuana use may not coincide with slowed reaction time. Conversely, braking impairment from low doses of alcohol may not be revealed by tests of balance. Electronic Publication     

A balanced placebo investigation of the effects of alcohol vs. alcohol expectancy on simulated driving behavior

The present investigation employed a balanced placebo design to examine the effects of alcohol versus the belief that one has consumed alcohol, i.e., alcohol expectancy, on error production while operating a driving simulator. The male subjects employed were social drinkers, having no history of alcohol abuse. The alcoholic beverage consisted of vodka and tonic in the ratio of 1:5, resulting in a mean blood alcohol level of .064%. The placebo beverage consisted of water and tonic, also in the ratio 1:5. Principal findings were that alcohol ingestion had a debilitating effect on certain measures of driving behavior (operation of brakes, steering), whereas the belief that one had consumed alcohol had no discernable effects. The results are discussed in relation to other findings using the balanced placebo design. It was concluded that reckless driving under the influence of alcohol, is at least partly a result of the pharmological effects of ethanol.     

Effects of d-amphetamine on simulated driving performance before and after sleep deprivation

Rationale

Stimulant drugs are commonly abused and also used to promote wakefulness, yet their effects on driving performance during sleep deprivation have not been thoroughly researched in experimental studies.

Objectives

The aims were to assess the effects on fundamental driving parameters during simulated driving of two doses of d-amphetamine and further to assess the interaction between d-amphetamine and sleep deprivation.

Methods

A double-blind, placebo-controlled experiment including 18 healthy male volunteers was conducted.

Results

The participants felt more alert when taking a dose of d-amphetamine than when taking placebo, and the effect was stronger for the higher dose. However, the data did not show any evidence that taking d-amphetamine prevented the subjects from becoming successively sleepier during the night. A significant main effect of the dose was found for three out of the five primary indicators where the lower dose led to improved driving. These indicators were crossing-car reaction time, and coherence and delay from a car-following event. Regarding sleep deprivation, a main effect was found for four of the primary indicators and three of the secondary indicators. The results showed overall impaired driving with respect to standard deviation of lateral position and delay in reaction time when the sleep-deprived conditions were compared to the alert condition. We found no interactions between dose and sleep deprivation for any of the performance indicators.

Conclusions

Our results suggest that administration of d-amphetamine does not compensate for impairment of driving due to fatigue. The positive effects of 10?mg were not further improved or even sustained when increasing the dose to 40?mg.     

The effects of the opioid pharmacotherapies methadone, LAAM and buprenorphine, alone and in combination with alcohol, on simulated driving

While methadone is currently the primary pharmacotherapy used in the treatment of heroin dependence in Australia, levo-alpha-acetyl-methodol (LAAM) and buprenorphine are new pharmacotherapies that are being examined as alternatives to methadone maintenance treatment. The aim of this research is to consider the effects of the methadone, buprenorphine and LAAM, as used in maintenance pharmacotherapy for heroin dependence, upon simulated driving. Clients stabilised in methadone, LAAM and buprenorphine treatment programs for 3 months, and a control group of non-drug-using participants, took part in this study which involved operating a driving simulator over a 75 min period. All participants attended one session without alcohol and one session with alcohol at around the 0.05% blood alcohol level. Simulated driving skill was measured through standard deviations of lateral position, speed and steering wheel angle, and reaction time to a subsidiary task was also measured. While alcohol impaired all measures of driving performance, there were no differences in driving skills across the four participant groups. These findings suggest that typical community standards around driving safety should be applied to clients stabilised in methadone, LAAM and buprenorphine treatment. The findings are important in terms of the widespread implementation of these treatment options in Victoria given that a large proportion of pharmacotherapy clients drive.     

Effects of antihistamines,chlormezanone and alcohol on psychomotor skills related to driving

Summary The effects of diphenhydramine, meclastine, and chlormezanone, alone or in combination with alcohol, on psychomotor skills related to driving have been investigated in 300 healthy volunteers. A choice reaction test and two coordination tests were employed. — Diphenhydramine caused sedation, partly independent of the dose, and slightly impaired psychomotor performance. Some subjects were exceptionally sensitive to diphenhydramine induced impairment of skills. It enhanced the effects of alcohol. — Meclastine did not impair psychomotor performance. A 1.5 mg dose did not enhance the effects of alcohol, but 3 mg did, although it was less potent than 50 mg of diphenhydramine. — Chlormezanone 200 mg had a relaxing effect which became apparent as a shortened reaction time at 30 min. Chlormezanone 400 mg did not affect psychomotor performance, nor did it enhance the effects of alcohol on psychomotor skills.     

Effects of emedastine and cetirizine, alone and with alcohol, on actual driving of males and females

Emedastine is registered in its country of origin (Japan) as an antihistamine for the indication of seasonal allergic rhinitis. Further research on the drug's sedating properties was needed to secure its registration elsewhere. The present study was designed to compare the effects of emedastine 2 mg and 4 mg twice daily after single and repeated doses, on actual driving performance versus those of cetirizine 10 mg once daily and placebo; and to determine how repeated doses of each drug interact with alcohol to affect driving. Each treatment was administered for 5 days to 19 healthy volunteers (nine men and ten women, aged 21-45 years) according to a four-period double-blind cross-over design. Driving performance was measured in a standardized test between 3 and 4 h after administration of the morning dose on days 1, 4 and 5. Alcohol, sufficient for achieving a blood alcohol concentration of 0.05 g/dl was given before driving on day 5 of each period. Both emedastine doses similarly and significantly impaired driving in every test. The effects of cetirizine were less. They were significant over days 1, 4 and 5 combined, although not separately. Women were more impaired by both drugs. Alcohol increased driving impairment similarly in every condition. Subjects were only able to discriminate the sedating and impairing effects of the first dose of emedastine 4 mg from placebo. Emedastine, in oral doses of 2 mg and 4 mg twice daily, is sedating and impairs driving. The drug could therefore constitute a traffic hazard and its users should be warned accordingly.     

Driver training conditions affect sensitivity to the impairing effects of alcohol on a simulated driving test [corrected

Research shows that prior behavioral training in a challenging environment reduces alcohol-induced impairment on simple psychomotor tasks. However, no studies have examined if this relationship generalizes to driving performance. The present study examined simulated driving performance and tested the hypothesis that a challenging training history would protect against the impairing effects of alcohol on driving performance. The challenging training history involved driving in a visually-impoverished environment. Thirty adults were randomly assigned to one of three groups. Two groups were tested under alcohol (0.65 g/kg) after prior experience performing the task under either a visually-impoverished environment or a normal visual environment. The remaining group served as a control and was trained and tested under the visually-impoverished condition environment. Results showed that individuals trained in the impoverished environment displayed sober levels of performance when their performance was subsequently tested under alcohol. By contrast, volunteers trained in a normal environment showed impairment under alcohol. The findings suggest that differences in driving training history can affect a driver's sensitivity to the impairing effects of alcohol.