Driving performance of long-term users of sedating antidepressants and benzodiazepines.

OBJECTIVE: Using benzodiazepines and certain antidepressants is associated with an increased risk of motor vehicle crashes due to impaired driving skills. Hence, several countries prohibit people who use these drugs from driving. Traffic regulations for driving under the influence of these drugs are, however, largely based on single-dose studies with healthy participants. The effects of drugs on chronic users may be different because of potential development of tolerance or by adapting behavior. In this study, we test the effects of anti-depressants, hypnotics, or anxiolytics use on driving performance in patients who use these drugs for different durations and compare the effects to healthy controls' performance. METHODS: Sixty-six healthy controls and 82 medication users were recruited to perform four drives in a driving simulator. Patients were divided into groups that used anti-depressants, hypnotics, or anxiolytics, for shorter or longer than 3 years (i.e. LT3- or LT3+, respectively). The minimum term of use was 6 months. Driving behavior was measured in terms of longitudinal and lateral control (speed variability and Standard Deviation of Lateral Position: SDLP), brake reaction time, and time headway. Impaired driving performance was defined as performing similar to driving with a Blood Alcohol Concentration of 0.5‰ or higher, determined by means of non-inferiority analyses. RESULTS: Reaction time analyses revealed inconclusive findings in all groups. No significant performance differences between matched healthy controls, LT3- (n = 2), and LT3+ (n = 8) anxiolytics users were found. LT3+ antidepressants users (n = 12) did not perform inferior to their matched controls in terms of SDLP. LT3- hypnotics users (n = 6) showed more speed variability than their matched healthy controls, while this effect was not found for the LT3+ group (n = 14): the latter did not perform inferior to the healthy controls. Regarding Time Headway, no conclusions about the LT3- hypnotics group could be drawn, while the LT3+ group did not perform inferior compared to the control group. CONCLUSIONS: The small number of anxiolytics users prohibits drawing conclusions about clinical relevance. Although many outcomes were inconclusive, there is evidence that some elements of complex driving performance may not be impaired (anymore) after using antidepressants or hypnotics longer than 3 years.

Alcohol metabolism in hangover sensitive versus hangover resistant social drinkers.

BACKGROUND: Previous research demonstrated that urinary ethanol concentrations were significantly lower in hangover resistant individuals compared to drinkers who reported having a hangover. This finding suggests that the rate of ethanol metabolism is faster in drinkers who do not experience an alcohol hangover. This study aimed to directly compare alcohol metabolism after administering a low dose of ethanol to hangover sensitive drinkers and hangover resistant drinkers. METHODS: Social drinkers who previously participated in hangover trials at Utrecht University were invited to participate. It was aimed to include 12 hangover resistant drinkers and 12 hangover sensitive drinkers. Participants consumed alcohol to reach a breath alcohol concentration (BrAC) of 0.05%. Every 5 min BrAC was determined, until BrAC reached zero. Every 15 min, the Karolinska Sleeping Scale (KSS) was administered to assess subjective sleepiness, and subjective intoxication was measured. RESULTS: Data of N = 23 participants with a mean age of 22.4 (±1.9) years was included in the analyses. No significant difference in BrAC over time was found between the hangover resistant group and the hangover sensitive group. In line, subjective sleepiness scores and subjective intoxication ratings did not significantly differ between the groups at any point in time after alcohol consumption. CONCLUSION: Hangover resistant individuals and hangover sensitive drinkers did not significantly differ on BrAC, subjective sleepiness, and subjective intoxication after consuming a moderate amount of alcohol. These findings suggest that drinkers who usually experience hangovers after a heavy drinking occasion do not experience alcohol intoxication differently than hangover resistant drinkers.

Urine methanol concentration and alcohol hangover severity.

BACKGROUND: Congeners are substances, other than ethanol, that are produced during fermentation. Previous research found that the consumption of congener-rich drinks contributes to the severity of alcohol hangover. Methanol is such a congener that has been related to alcohol hangover. Therefore, the aim of this study was to examine the relationship between urine methanol concentration and alcohol hangover severity. METHODS: N = 36 healthy social drinkers (22 females, 14 males), aged 18-30 years old, participated in a naturalistic study, comprising a hangover day and a control day (no alcohol consumed the previous day). N = 18 of them had regular hangovers (the hangover group), while the other N = 18 claimed to be hangover-immune (hangover-immune group). Overall hangover severity was assessed, and that of 23 individual hangover symptoms. Urine methanol concentrations on the hangover and control days were compared, and correlated to hangover (symptom) severity. RESULTS: Urine methanol concentration was significantly higher on hangover days compared to control days (p = 0.0001). No significant differences in urine methanol concentration were found between the hangover group and hangover-immune group. However, urine methanol concentration did not significantly correlate with overall hangover severity (r = -0.011, p = 0.948), nor with any of the individual hangover symptoms. These findings were observed also when analyzing the data separately for the hangover-immune group. In the hangover group, a significant correlation with urine methanol concentration was found only with vomiting (r = 0.489, p = 0.037). CONCLUSION: No significant correlation was observed between urine methanol concentration and hangover severity, nor with individual core hangover symptoms.

Characteristics of social drinkers with and without a hangover after heavy alcohol consumption.

BACKGROUND: A number of social drinkers claim that they do not experience next-day hangovers despite consuming large quantities of alcohol. The aim of this study was to investigate the characteristics of drinkers who claim to be hangover immune and compare them with drinkers who do report having hangovers. METHODS: A total of 36 social drinkers participated in a naturalistic study consisting of a hangover day (alcohol consumed) and a control day (no alcohol consumed). Data were collected on alcohol consumption, demographics, sleep, next-day adverse effects, and mood. Data from drinkers with a hangover (N=18) were compared with data from drinkers who claim to be hangover immune (N=18). RESULTS: Drinkers with a hangover reported drowsiness-related symptoms, symptoms related to reduced cognitive functioning, and classic hangover symptoms such as headache, nausea, dizziness, weakness, and stomach pain. Corresponding mood changes comprised increased feelings of depression, anger-hostility, fatigue, and reduced vigor-activity. In contrast, hangover-immune drinkers reported relatively few hangover symptoms, with only mild corresponding severity scores. The reported symptoms were limited to drowsiness-related symptoms such as sleepiness and being tired. The classic hangover symptoms were usually not reported by these drinkers. CONCLUSION: In contrast to drinkers with a hangover, for those who claim to be hangover immune, next-day adverse effects of alcohol consumption are limited to a mild increase in drowsiness-related symptoms.

Comparing treatment effects of oral THC on simulated and on-the-road driving performance: testing the validity of driving simulator drug research.

RATIONALE: The driving simulator provides a safe and controlled environment for testing driving behaviour efficiently. The question is whether it is sensitive to detect drug-induced effects. OBJECTIVE: The primary aim of the current study was to investigate the sensitivity of the driving simulator for detecting drug effects. As a case in point, we investigated the dose-related effects of oral ∆(9)-tetrahydrocannabinol (THC), i.e. dronabinol, on simulator and on-the-road driving performance in equally demanding driving tasks. METHOD: Twenty-four experienced driver participants were treated with dronabinol (Marinol®; 10 and 20 mg) and placebo. Dose-related effects of the drug on the ability to keep a vehicle in lane (weaving) and to follow the speed changes of a lead car (car following) were compared within subjects for on-the-road versus in-simulator driving. Additionally, the outcomes of equivalence testing to alcohol-induced effects were investigated. RESULTS: Treatment effects found on weaving when driving in the simulator were comparable to treatment effects found when driving on the road. The effect after 10 mg dronabinol was however less strong in the simulator than on the road and inter-individual variance seemed higher in the simulator. There was, however, a differential treatment effect of dronabinol on reactions to speed changes of a lead car (car following) when driving on the road versus when driving in the simulator. CONCLUSION: The driving simulator was proven to be sensitive for demonstrating dronabinol-induced effects particularly at higher doses. Treatment effects of dronabinol on weaving were comparable with driving on the road but inter-individual variability seemed higher in the simulator than on the road which may have potential effects on the clinical inferences made from simulator driving. Car following on the road and in the simulator were, however, not comparable.

Short-term cardiovascular responses to changing task demands.

When measuring operator states the predictive power of cardiovascular and respiratory measures in relation to mental workload has been questioned. One of the main questions is to what extent do cardiovascular measures actually reflect mental workload. This question arises because good measures of mental workload should be sensitive to changes in mental effort alone and not to other influences or at least the changes associated with mental workload should be easy to isolate. In the case of cardiovascular measures, the physiological change brought on by the baroreflex is a compensatory control effect that can potentially overshadow changes in physiology due to mental effort and therefore reduce the usefulness of cardiovascular measures. However, this does not need to be the case. Despite the effects caused by the baroreflex differences in heart rate, heart rate variability and other cardiovascular measures associated with task related effort can still be found using short-term response patterns. The short-segment analysis approach described in this paper is based on a time-frequency method in which the spectral power of the cardiovascular measures in specified spectral bands is computed from small time segments, i.e. 30 s. To demonstrate the effectiveness of this technique two studies which made use of a simulation of an ambulance dispatcher's task are described, both with easy and difficult task conditions. A short-lasting increase in task demand was found to be reflected in short-lasting increases in heart rate and blood pressure in combination with corresponding decreases in heart rate variability and blood pressure variability. These effects were larger in easy task conditions than in hard conditions, likely due to a higher overall effort-level during the hard task conditions. However, the developed measures are still very sensitive to mental effort and if this brief segmentation approach is used cardiovascular measures show promise as good candidates for reflecting mental effort during the assessment of operator state.

Do young novice drivers overestimate their driving skills more than experienced drivers? Different methods lead to different conclusions.

In this study we argue that drivers have to make an assessment of their own driving skills, in order to sufficiently adapt to their task demands in traffic. There are indications that drivers in general, but novice drivers in particular, overestimate their driving skills. However, study results differ on the subject of self-assessment of skills. The objectives of this paper are (1) to study whether novice drivers indeed overestimate their driving skills more than experienced drivers; and (2) to evaluate the influence of the method to measure self-assessment of skills (i.e. comparison to 'average' and 'peer' driver versus independent measures of own performance). The results show that the conclusion of whether novice drivers overestimate their driving skills is highly affected by the method chosen to measure self-assessment of skills. When drivers are asked to compare themselves to the average and peer driver, we can conclude that novice drivers are not as optimistic about their driving skills as has been reported in the past. They seem to recognize that they are not as skilled (yet) as the average driver. However, when comparing their self-assessment with their actual behaviour there are indications that they overestimate their driving skills.

Let them experience a ride under the influence of alcohol; a successful intervention program?

A considerable amount of all traffic accidents can be attributed to driving under the influence of alcohol. In particular the group of drivers aged 18-24 years is involved in many serious traffic accidents where alcohol turns out to be a major factor. In fact this age group shows about three times as many alcohol related traffic fatalities as all other categories of road users. The intervention program "Alcohol-free on the road" (Dutch: "Alcoholvrij op weg") aims to enhance young people's awareness of the effects of alcohol by letting them personally experience the effect of alcohol on their driving abilities. To this end, young drivers were invited to a closed circuit and allowed to drive first sober and then intoxicated, guided and guarded by driving instructors. Based on several other studies it was thought that a realistic experience of the effects of alcohol on driving abilities may contribute to a better understanding of the impact of alcohol and may stimulate attitudes that are needed to support the conscious decision not to drive while intoxicated. After more than ten years of running and data collection, 1200 young drivers have participated in the intervention program. In a quasi-experimental study with a non-equivalent group design, the program is evaluated in order to assess its effectiveness both with respect to the attitudes of the participants and the actual relevant behaviour in the years after the alcohol experience intervention program they attended, i.e. the incidence of actually driving under the influence of alcohol. To do this, a questionnaire was sent to a subset (415) of the participants who have completed the program, along with a control group (450), to compare attitudes and actual behaviour. In addition, the Public Prosecutor checked the files of those who responded, for the occurrence of driving under the influence of alcohol. The group that participated in the alcohol intervention program showed more awareness about the dangers of driving while intoxicated than the control group, and this group reported improved alcohol law compliance. Furthermore, less participants in the intervention program than in the control group were present in the Public Prosecutor files, respectively 0.7% and 4.2%. Hence, the alcohol driving experience intervention program might turn out to be effective and successful in decreasing driving under the influence of alcohol. Although the results of the present study are no more than suggestive, they may be considered a first step towards demonstrating the effectiveness of this type of intervention. However, the intervention is unique and warrants a more robust evaluation. A large-sized randomized controlled trial should be conducted in the next phase to confirm the findings that the intervention program is a suitable educational tool to decrease driving under the influence of alcohol. The present paper serves to raise awareness of this intervention and its potential.

Criteria for driver impairment.

Most traffic accidents can be attributed to driver impairment, e.g. inattention, fatigue, intoxication, etc. It is now technically feasible to monitor and diagnose driver behaviour with respect to impairment with the aid of a limited number of in-vehicle sensors. However, a valid framework for the evaluation of driver impairment is still lacking. To provide an acceptable definition of driver impairment, a method to assess absolute and relative criteria was proposed to fulfil the paradoxical goal of defining impaired driving which is consistent yet adaptable to interindividual differences.

Dissociable effects of a single dose of ecstasy (MDMA) on psychomotor skills and attentional performance.

Ecstasy (3,4-methylenedioxymethamphetamine, MDMA) is a psychoactive recreational drug widely used by young people visiting dance parties, and has been associated with poor cognitive function. The current study assessed the influence of a single dose of MDMA 75 mg and alcohol 0.5 g/kg on cognition, psychomotor performance and driving-related task performance. Twelve healthy recreational ecstasy users participated in an experimental study conducted according to a double-blind, double-dummy, placebo-controlled three-way cross-over design. MDMA improved psychomotor performance, such as movement speed and tracking performance in a single task, as well as in a divided attention task. MDMA impaired the ability to predict object movement under divided attention. However, the inability to accurately predict object movement after MDMA may indicate impairment of particular performance skills relevant to driving. There was no effect of MDMA on visual search, planning or retrieval from semantic memory.

A comparison of different ways to approximate time-to-line crossing (TLC) during car driving.

Three experiments are presented in which the accuracy of different methods to approximate time-to-line crossing is assessed the first experiment TLC was computed, using a trigonometric method, during normal driving while the vehicle stayed in lane. The minima of TLC were compared with two approximations and it was found computing TLC as lateral distance divided by lateral velocity gave poor results. It was concluded that this simple approximation is not suitable for measuring TLC minima in studies of driver behaviour. A way of computing TLC that takes account of the curved path of the vehicle resulted in a good fit of TLC minima. In two other experiments the vehicle exceeded the lane boundary, either intentionally as a result of a lane change manoeuvre, or unintentionally as a result of impaired driving. In these cases no TLC minima exists since these only occur as a result of correcting steering actions to stay within the lane. In contrast to normal lane keeping, it was found that prior to crossing the lane boundary, the simple approximation resulted in more accurate estimation of available time before the lane boundary is exceeded compared to the more complex approximation. This indicates that for lane keeping support systems and systems that detect when the driver has fallen asleep and drifts out of lane, a simple algorithm for TLC estimation may give reliable results, while this algorithm is not accurate enough for more fundamental studies of driver behaviour. However, the reliability of the approximation is only satisfactory over a very short time range before the lane boundary is actual exceeded. This may result in warnings that come too late and result in too little time to respond for the driver.

Elderly and young driver's reaction to an in-car enforcement and tutoring system.

A system that contrasts driver behaviour with normative behaviour was tested in an advanced driving simulator. Drivers were provided with auditory and visual tutoring messages if deviations were detected from normative, i.e. legally allowed behaviour with respect to a selection of offences. Results showed that the system was very effective in increasing law-abiding behaviour, which has a major positive effect on traffic safety. However, driver mental effort, as indicated by self-reports and drivers' physiological states, was slightly increased in conditions where drivers received feedback. Opinion about the tutoring system was positive in terms of usefulness. Self-reports on satisfaction differed between age groups; young drivers rated it low, while elderly drivers held a positive attitude.

Effect of road layout and road environment on driving performance, drivers' physiology and road appreciation.

Infrastructural changes were implemented on rural 80 km/h roads in The Netherlands in an effort to reduce speeding. The road infrastructure changes were designed to produce discomfort for the speeding driver by providing noxious auditory and haptic feedback. On experimental roads, smooth-surface road width was reduced by using blocks of gravel chippings placed along the centre line and at intervals on road edges. It was predicted that these changes would increase mental load while driving, and thereby decrease speeding. In a field experiment 28 subjects drove an instrumented vehicle over experimental and control roads. A decrease in driving speed and swerving behaviour was found on the experimental roads, and this was coupled with a decrease in heart rate variability, consistent with an increase in mental load. Roads in two different road-side environments (woodland vs. moorland) were also tested. There were differences in driver appraisal of the two environments, but no interactions were observed between these appraisals and driving performance on the experimental roads. It is concluded that the infrastructural measures have a useful role to play in road safety through a reduction in driver speeding.

Training young cyclists to cope with dynamic traffic situations.

Two training methods were developed to teach young cyclists (8/9 years) how to behave in priority situations. One method was developed along the lines of the modelling principle. In earlier studies it was shown that this method is effective in teaching crossing strategies to young pedestrians. The other training method was based upon Anderson's Adaptive Control of Thought (ACT) theory, which describes the development of cognitive skills by proceduralisation and composition of behaviour and knowledge elements into automatic behaviour sequences. Two groups of children were trained with one of these methods. A control group did not receive traffic-related training in that period. The effect of the training was assessed by a knowledge test and a behaviour test. The results showed that the partly theoretical ACT approach initially resulted in an increased level of knowledge, which was found to have disappeared after a month. The modelling approach did not affect the level of knowledge. Both approaches had an equally positive effect on simple behavioural strategies, such as signalling and visual search behaviour. Correct application of priority rules appeared to be very difficult to teach. There was no effect of the two training methods. It seemed that children apply informal rules rather than formal rules when dealing with other traffic. It is hypothesized that these informal rules should form the starting point for training activities, because formal rules do not fit into children's cognitive framework of schemes, and therefore cannot be stored and retrieved effectively.

The use of psychophysiology to assess driver status.

Twenty subjects completed an on-the-road driving experiment, consisting of two different tests conducted on two separate days. A two-part test was administered while subjects were under the influence of alcohol (BAC < = 0.05%); a four-part test was administered without alcohol consisting of a 2.5 h driving test under vigilance conditions on a quiet highway. The order of the tests was balanced across subjects. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving impairment. Impairment of driving performance was measured in a standard driving test (SD lateral position and SD steering wheel movements) and in a recently developed car-following test (reaction to speed changes of a leading car).

Acute and subchronic effects of the H1-histamine receptor antagonist ebastine in 10, 20 and 30 mg dose, and triprolidine 10 mg on car driving performance.

1. The effects of a new antihistamine, ebastine (10, 20 and 30 mg), on several parameters of driving performance in actual traffic were studied in 15 healthy male volunteers. Subjects were treated for 5 days, and their driving performance tested on day 1 and day 5. The study was double-blind, placebo controlled and included the antihistamine triprolidine (10 mg sustained release) as an active drug control. 2. General tolerability was good except in one case following the reference compound triprolidine. No significant changes in driving performance were found with the new antihistamine ebastine at any dosage, on day 1 or day 5. Triprolidine (10 mg) significantly increased both the amount of weaving and the delay in following speed manoeuvres of a leading car, compared with placebo. 3. The results suggest that ebastine in doses up to 30 mg may be relatively safe for use by those who drive motor vehicles while under medication. The results do not warrant such a conclusion for triprolidine 10 mg.

Assessing driver status: a demonstration experiment on the road.

Twenty subjects completed an on-the-road experiment that consisted of two parts on two separate days. One was a one-hour driving test under the influence of alcohol (BAC less than = 0.05%), the second a two-and-a-half-hour driving test under vigilance conditions. Impairment of driving performance was measured in a car-following test as well as in a standard driving test. Changes in relevant physiological parameters, such as ECG and EEG, reflected changes in driver status and predicted driving performance impairment.