The relationship between alcohol dosage and performance decrement in humans

Evaluating the effect of drunk driving on fatal injuries among vulnerable road users in Taiwan: a population-based study

Background

Most studies have focused on injuries sustained by intoxicated drivers themselves, but few have examined the effect of drunk driving on injury outcomes among VRUs (vulnerable road users) in developing countries. This study aims to evaluate the effect of drunk driving on fatal injuries among VRUs (pedestrians, cyclists, or motorcyclists).

Methods

The data were extracted from the National Taiwan Traffic Crash Dataset from January 1, 2011, to December 31, 2019. Crashes involving one motorized vehicle and one VRU were considered. This study examines the effect of drunk driving by estimating multivariate logistic regression models of fatal injuries among VRUs after controlling for other variables.

Results

Among 1,416,168 casualties, the fatality rate of VRUs involved in drunk driving was higher than that of general road users (2.1% vs. 0.6%). Drunk driving was a significant risk factor for fatal injuries among VRUs. Other risk factors for fatal injuries among VRUs included VRU age ≥ 65 years (adjusted odds ratio [AOR]: 5.24, 95% confidence interval [CI]: 5.53–6.07), a nighttime accident (AOR: 4.52, 95% CI: 4.22–4.84), and being hit by a heavy-duty vehicle (AOR: 2.83, 95% CI: 2.26–3.55). Subgroup analyses revealed a linear relationship between driver blood alcohol concentration (BAC) and the risk of fatal injury among motorcyclists. Motorcyclists exhibited the highest fatality rate when they had a BAC ≤ 0.03% (AOR: 3.54, 95% CI: 3.08–4.08).

Conclusion

Drunk driving was associated with a higher risk of fatality for all VRUs. The risk of fatal injury among motorcyclists was linearly related to the BAC of the drunk drivers. Injuries were more severe for intoxicated motorcyclists, even those with BAC ≤ 0.03%, which is within the legal limit.

Influence of Alcohol Intake on the Parameters Evaluating the Body Center of Foot Pressure in a Static Upright Posture

To examine the influence of alcohol intake on various parameters evaluating the change in body center of foot pressure during a static upright posture, 11 healthy young males and females gave measures of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and body stability for 60 sec. in the Romberg posture (open eyes, closed feet) before and after the alcohol intake. The measurement was made with an Anima's stabilometer G5500. Data sampling frequency was 20 Hz. The subjects drank alcohol (Japanese sake 540 ml) within 10 min. After 10, 20, and 30 min. of alcohol intake, the same measurements were carried out. 24 parameters with higher trial-to-trial reliability were selected from the following 7 domains: distance, mean center of foot pressure, distribution of amplitude, area, velocity, frequency (power spectrum), and direction (vector) of body-sway and velocity. Parameters for distance, velocity, and area of body-sway significantly changed after alcohol intake, but the mean center of foot pressure and frequency of body-sway were unchanged. It was inferred that the mean center of foot pressure and frequency for body-sway did not change even if a nervous function decreased by the alcohol intake, and an upright posture was maintained by increasing the distance, area, and velocity of body-sway. Further, body-sway tends to increase in the medial/lateral direction as compared with the anterior/posterior direction.

Performance of a cognitive, but not visual, secondary task interacts with alcohol-induced balance impairment in novice and experienced motorcycle riders

The appropriateness of applying drink driving legislation to motorcycle riding has been questioned as there may be fundamental differences in the effects of alcohol on driving and motorcycling. It has been suggested that alcohol may redirect riders' focus from higher-order cognitive skills such as cornering, judgement and hazard perception, to more physical skills such as maintaining balance. To test this hypothesis, the effects of low doses of alcohol on balance ability were investigated in a laboratory setting. The static balance of twenty experienced and twenty novice riders was measured while they performed either no secondary task, a visual (search) task, or a cognitive (arithmetic) task following the administration of alcohol (0%, 0.02%, and 0.05% BAC). Subjective ratings of intoxication and balance impairment increased in a dose-dependent manner in both novice and experienced motorcycle riders, while a BAC of 0.05%, but not 0.02%, was associated with impairments in static balance ability. This balance impairment was exacerbated when riders performed a cognitive, but not a visual, secondary task. Likewise, 0.05% BAC was associated with impairments in novice and experienced riders' performance of a cognitive, but not a visual, secondary task, suggesting that interactive processes underlie balance and cognitive task performance. There were no observed differences between novice vs. experienced riders on static balance and secondary task performance, either alone or in combination. Implications for road safety and future 'drink riding' policy considerations are discussed.

Alcohol and human performance

The present paper presents a comprehensive review of studies concerned with the effects of alcohol on human performance. It attempts to review the studies within the framework of the information processing model. The effects of alcohol on information processing and transmission rates, sensory and perceptual processes, motorcontrol processes, attentional processes, and cognitive processes are described and discussed. It is proposed that such a processes analysis of human performance is a useful vehicle to describe the specific effects of alcohol. From the review it is concluded that much of the evidence from simple task description is equivocal. However, when information load is increased, when the stimulus-response incompatibility increases, and when the number of competing information processes occur in 'parallel', then a strong, consistent and coherent pattern of performance deterioration is associated with alcohol consumption.

Comparing the Effects of Light Alcohol Consumption on Human Response to Auditory and Visual Stimuli

The purpose of this study is to examine the effects of various levels of alcohol consumption on human response to auditory and visual stimuli in terms of reaction time, movement time, total reaction time, and error rate. Placebo level and three low-level alcohol doses were randomly assigned to 20 male university student volunteers. 30 min. after consuming the alcohol or placebo, participants responded to either auditory or visual stimuli. Total reaction time increased significantly at the mid-low dose of alcohol (0.3 g/kg). For alcohol doses less than .5 g/kg, the change in total reaction time was confined to reaction time, i.e., the processing time between onset of stimulus and onset of movement. Effects of alcohol were significantly more pronounced in the choice-type tests. Notably, the effects of alcohol on total reaction time and error rate were significant for auditory but not visual stimuli.

Alcohol and driving: is the 0.05% blood alcohol concentration limit justified?

This paper reviews the findings of experimental and laboratory research to determine whether there is sufficient evidence to support a uniform 0.05% blood alcohol concentration (BAC) as the legal limit for driving. Statistically significant and meaningful decrements in driving-related performance were identified at 0.05% BAC or below in many studies. Younger and inexperienced drinkers and drivers appear to be at greatest risk for alcohol-related traffic crashes. It is concluded that on scientific grounds, there is support for setting the legal limit at 0.05%. The setting of a uniform 0.05% BAC statutory limit should be but one effort within a comprehensive approach including other legal, social, behavioural and environmental strategies to deal with the drink driving problem.

Toward cost-benefit analysis of acute behavioral effects of toluene in humans

There is increasing interest in being able to express the consequences of exposure to potentially toxic compounds in monetary terms in order to evaluate potential cost-benefit relationships of controlling exposure. Behavioral effects of acute toluene exposure could be subjected to cost-benefit analysis if the effects of toluene were quantitatively compared to those of ethanol ingestion, which has been monetized for applied contexts. Behavioral effects of toluene and ethanol were quantified by meta-analysis of studies from the peer-reviewed literature describing their effects on choice reaction time (reaction time in a test requiring a subject to choose among two or more alternatives before responding). The internal doses of these compounds were estimated by a general physiological and toxicokinetic (GPAT) simulation from exposure parameters provided in the reports. The reported effects were converted to a common metric (proportion of baseline) and related to the estimated internal doses of toluene and ethanol, from which dose-effect equations were fitted. The estimated effect of toluene was compared to the estimated effect of ethanol on the same dependent variable by deriving a dose-equivalence equation (DEE) to express the dose of toluene as an equivalent dose of ethanol on the basis of equal effect magnitude. A nomogram was constructed by GPAT simulation to relate the environmental exposure concentration of toluene to the equivalent effect magnitude of a range of ethanol internal doses. Behavioral effects and their evaluation are determined by internal doses, which in turn are determined by a variety of variables. In addition to concentration and duration of exposure, which determine internal dose by pharmacokinetic processes, the activity level of exposed persons is a major factor. This analysis provides a continuous function of the consequences of toluene exposure expressed as ethanol-equivalent doses within confidence limits. The resulting function has the potential to estimate the monetary values of behavioral deficits caused by a range of exposures to toluene from existing monetized information on ethanol.

Gender Differences in Body-Sway Factors of Center of Foot Pressure in a Static Upright Posture and under the Influence of Alcohol Intake

This study aimed to examine gender differences in 4 body-sway factors of the center of foot pressure (CFP) during a static upright posture and the influence of alcohol intake on them. Four body-sway factors were interpreted in previous studies using factor analysis (the principal factor method and oblique solution by promax-rotation) on 220 healthy young males and females as follows; unit time sway, front-back sway, left-right sway and high frequency band power. The CFP measurement for 1 min was carried out twice with 1 min rest. The measurements of blood pressure, heart rate, whole body reaction time, standing on one leg with eyes closed, and CFP were carried out before and after the alcohol intake using 11 healthy young males and females. The measurement device used was an Anima's stabilometer G5500. The data sampling frequency was 20 Hz. Reliability of 4 body-sway factors was very high. Significant gender differences were found in the left-right sway and the high frequency band power factors, but the influence on body-sway is, as a whole, can be disregarded. These four sway factors can determine the influence of alcohol intake as efficient as 32 sway parameters.

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.

Developing measures of fatigue using an alcohol comparison to validate the effects of fatigue on performance

The effects of 28 h of sleep deprivation were compared with varying doses of alcohol up to 0.1% blood alcohol concentration (BAC) in the same subjects. The study was conducted in the laboratory. Twenty long-haul truck drivers and 19 people not employed as professional drivers acted as subjects. Tests were selected that were likely to be affected by fatigue, including simple reaction time, unstable tracking, dual task, Mackworth clock vigilance test, symbol digit coding, visual search, sequential spatial memory and logical reasoning. While performance effects were seen due to alcohol for all tests, sleep deprivation affected performance on most tests, but had no effect on performance on the visual search and logical reasoning tests. Some tests showed evidence of a circadian rhythm effect on performance, in particular, simple reaction time, dual task, Mackworth clock vigilance, and symbol digit coding, but only for response speed and not response accuracy. Drivers were slower but more accurate than controls on the symbol digit test, suggesting that they took a more conservative approach to performance of this test. This study demonstrated which tests are most sensitive to sleep deprivation and fatigue. The study therefore has established a set of tests that can be used in evaluations of fatigue and fatigue countermeasures.

Profile of acute tolerance to three sedative anxiolytics

Acute tolerance, defined as a decreasing drug effect relative to drug-plasma levels (DPL) over a period of minutes to a few hours, is pronounced following single doses of diazepam or pentobarbital. Both of these lipid-soluble drugs produce an early peak behavioral impairment and subsequent rapid recovery component that is followed by a much slower blood-drug rise time. These pronounced early peak effects were not shared by alcohol, and contribute significantly to the lack of correlation between impairment and DPL.

A comparative model: reaction time performance in sleep-disordered breathing versus alcohol-impaired controls

OBJECTIVES/HYPOTHESIS

Patients with sleep-disordered breathing have reaction time deficits that may lead to catastrophic accidents and loss of life. Although safety guidelines do not exist for unsafe levels of sleepiness, they have been established for unsafe levels of alcohol consumption. Since reaction time performance is altered in both, we prospectively used seven measures of reaction time performance as a comparative model in alcohol-challenged normal subjects with corresponding measures in subjects with sleep-disordered breathing.

STUDY DESIGN

Institutional Review Board-approved, nonrandomized prospective controlled study.

METHODS

Eighty healthy volunteers (29.1+/-7.5 y of age, 56.3% female subjects) performed four reaction time trials using a psychomotor test at baseline and at three subsequent rising alcohol-influenced time points. The same test without alcohol was given to 113 subjects (47.2+/-10.8 y of age, 19.3% female subjects) with mild to moderate sleep-disordered breathing.

RESULTS

Mean blood alcohol concentrations (BACs) in the alcohol-influenced subjects at baseline and three trials were 0, 0.057, 0.080, and 0.083 g/dL. The sleep-disordered subjects had mean respiratory disturbance indices of 29.2 events per hour of sleep. On all seven reaction time measures, their performance was worse than that of the alcohol subjects when BACs were 0.057 g/dL. For three of the measures, the sleep-disordered subjects performed as poorly as or worse than the alcohol subjects when alcohol levels were 0.080 g/dL. These results could not be explained by sex or age differences.

CONCLUSION

The data demonstrate that sleep-disordered subjects in this study (with a mean age of 47 y) with mild to moderate sleep-disordered breathing had worse test reaction time performance parameters than healthy, nonsleepy subjects (with a mean age of 29 y) whose BAC is illegally high for driving a commercial motor vehicle in California. This comparative model points out the potential risks of daytime sleepiness in those with sleep-disordered breathing relative to a culturally accepted standard of impairment.

Alcohol and visual performance

1. The authors examined the effect of acute alcohol consumption on a set of visual tasks: visual short term memory, depth perception, and attention. 2. In a repeated measurement design, thirteen subjects performed the tasks once sober and once intoxicated with 0.8 g/kg body weight pure ethanol in orange juice (33% alcohol). Subjects underwent a neuropsychological (Benton test) and a psychophysical test (vernier discrimination) both assessing visual short term memory, the test d2 as a measure of attention and concentration, and a psychophysical depth perception task. 3. Subjects demonstrated significant alcohol-related impairments in depth perception and in visual short term memory as assessed by the vernier discrimination task. However, the neuropsychological Benton test and test d2 failed to reveal alcohol-related changes in performance-probably due to superimposed learning effects. Performance was neither correlated with blood alcohol levels (BAL) nor perceived intoxication. Even though the current BAL was known to the subjects, only half of them demonstrated a close correlation between BAL and perceived intoxication.

Impact of the 1970 legal BAC 0.05 mg% limit legislation on drunk-driver-involved traffic fatalities, accidents, and DWI in Japan

Official statistics of motor vehicle fatality data have indicated that alcohol involvement in fatal crashes has declined substantially in Japan since 1970. The national campaign against drunken driving in Japan provides a natural experiment in which to test the predictions of deterrence theory. Utilizing official data over the 1960-1995 period, we report conclusive evidence that 1970s legislation is having a measurable and long-term effect on alcohol-related motor vehicle fatalities. Enactment of the lower legal blood alcohol limit with a combination of other severe sanctions has been more desirable in the prevention of alcohol-related fatalities in the long term as shown in this study. Further extensive research is necessary to investigate performance at the lower legal limit in other societies in order to inspire a strong "international lobby" to support the reduced legal blood alcohol limit for drivers all over the world, as there is no doubt that a reduction in alcohol-impaired driving will result in a substantial savings of human lives and resource worldwide.

Testing the global-slowing hypothesis: are alcohol's effects on human performance process-specific or task-general?

In an interesting recent meta-analysis, Maylor and Rabbitt (1993) suggested that alcohol's effects on human performance may not be process- or stage-specific, but reflect a general, undifferentiated, cognitive slowing. According to this view, performance is globally slowed by a constant multiplicative fraction (b), such that the longer a process takes without alcohol on board (a -), the more it will be slowed by alcohol (a +). In summary: RTa+ = b b (RTa-). In this sense, the effects of alcohol are determined simply by the duration of a process or stage--not by its function or content--and attempts to map the effects of alcohol to specific cognitive operations are essentially futile. This global-slowing hypothesis entails, then, (i) that the function relating RTa+ to RTa- will be linear and increasing; (ii) that the value of b will be significantly greater than 1.0; and (iii) that all experimental factors which increase the complexity (hence, duration) of a task or stage will interact with alcohol. In this study we tested the global-slowing hypothesis directly using fixed set, varied set and concurrent sets item-recognition paradigms. All three tasks showed convincing additivity between alcohol and other key experimental factors which affect response latency (e.g., setsize, response type); there was no hint of any of the spectrum of significant interactions predicted by the global-slowing hypothesis. A meta-analysis of varied set latencies, analogous to Maylor and Rabbitt's, yielded a reasonably linear alcohol/no-alcohol function, but with a slope constant (b) less than 1.0. In all, the data provided little support for the global-slowing hypothesis.

Alcohol pharmacodynamics in young-elderly adults contrasted with young and middle-aged subjects

Effects of aging on ethyl alcohol (EtOH) pharmacodynamics were examined over progressive dosing schedules (0.4, 0.6, 0.8, 1.0 g/kg) in groups of young (25.0 +/- 2.9 years), middle-aged (41.1 +/- 6.6 years), and young-elderly adults (60.9 +/- 2.6 years) using three computerized cognitive-neuromotor tasks: digit-symbol substitution (DSS), keypad reaction time (KRT), and subcritical tracking (SCT). Hysteresis curves of performance impairment (adjusted for pre-drug baseline) as a function of blood alcohol concentration (BAC) were examined for time-course effects, and regression analyses were performed to assess the contribution of age beyond that accounted for by BAC. Results reflected differences in the patterning but not magnitude of impairment for elderly subjects, with earlier decrements and more rapid acute tolerance observed for DSS, in conjunction with less pharmacodynamic sensitivity for SCT. Regression analyses furthermore indicated that age and impairment were negatively related, arguing against synergistic intoxication effects as a function of aging. Analyses specifically comparing performance at baseline versus legally intoxicating BACs (> 1.0 mg/ml) likewise reflected a lack of interactive effects involving the elderly. Elderly subjects nevertheless exhibited significantly lower baseline performance for DSS and KRT than young subjects and achieved higher BACs with equivalent doses. These latter findings support the exercise of caution by elderly individuals consuming EtOH prior to engaging in neuromotor pursuits such as driving.

Dose dependent effects of alcohol on visual evoked potentials

The effects of various alcohol doses on components of the visual evoked potential were investigated. Using a repeated measures, Latin square design, five alcohol dose conditions were administered to ten male subjects: 0.00 (placebo); 0.28; 0.36; 0.54 and 0.72 g/kg total body weight. EEG responses to a reversing checker board stimulus were measured in a standard oddball paradigm. In the alcohol conditions, latencies of the P1 and P2 components of the VEP were unaffected. However, reaction time, and the latencies of N2 and P3 displayed significant dose related increases with increasing blood alcohol levels. Further, RMS power of the P3 complex was reduced by higher alcohol doses, as was the N2-P3 amplitude difference at central and parietal sites. It is concluded that the latency and power of the endogenous components of the VEP are altered by alcohol, without effects being seen in earlier components.

Effect of alcohol measured by dynamic posturography

Thirteen healthy male volunteers aged 21-42 years (mean 27 years) were assessed by dynamic posturography before and after ingestion of alcohol. Each subject was given 0.6 g alcohol per kg body weight in fruit juice to be drunk within 10 min. Alcohol levels in blood samples at 15, 45 and 75 min after ingestion were assessed by gas chromatography. Posturographic measurements were conducted at 30 and 60 min after alcohol administration. Dynamic posturography comprises a sensory organization part in which the support surface and visual surround are either stable or referenced to the patient's sway and the test conditions are eyes open or eyes closed. In a movement coordination part the platform makes active movements. Alcohol levels were 0.40% (SD 0.14) after 45 min and 0.51% (SD 0.14) at 75 min. All subjects presented positional alcohol nystagmus and gaze nystagmus after 45 min. In the sensory organization part of the dynamic posturography in test conditions with eyes closed and the head in neutral position, both with stable (p less than 0.039) and sway-referenced platform (p less than 0.017), alcohol effects were found. In the test condition with sway referenced platform and stable visual surround the effect of alcohol was close to significance (p less than 0.069). When the head was tilted to either side, no effect of alcohol was detected, nor in the movement coordination test. It is concluded that dynamic posturography can detect the effect of alcohol on static and dynamic equilibrium. Test conditions with absent vision appear to be the most sensitive. The results in static conditions are well in agreement with previous studies; the findings under dynamic conditions are new.

Individual differences in the sedating effects of ethanol

Twenty-four healthy, normal-sleeping, males aged 21-35 were screened for basal levels of sleepiness using the Multiple Sleep Latency Test (MSLT). Twelve subjects had basal average daily sleep latencies of less than or equal to 6 min (sleepy) and 12 had latencies of greater than or equal to 16 min (alert) on the MSLT. Subjects consumed either ethanol (0.75 mg/kg) or placebo at 0900-0930 after spending 8 hr time in bed (TIB) the previous night. Sleep latency was measured at 1000, 1200, 1400, and 1600 hr. Divided attention performance and the Stanford Sleepiness Scale (SSS) were assessed at 1100 hr. Breath ethanol concentration (BEC) was determined prior to each latency test. Ethanol decreased average daily sleep latency, divided attention scores and SSS ratings. There were individual differences in the sedating and impairing effects of ethanol, related to subjects' basal level of sleepiness/alertness. The alert subjects exhibited longer sleep latencies and higher performance scores after ethanol administration than the sleepy subjects after placebo. Subjectively the groups had a similar level of sleepiness on placebo and were similarly sedated with ethanol.

Spatial learning of visual 'nonsense figures' during experimental ethanol intoxication

The interaction of alcohol and visuospatial learning was evaluated during two experimental sessions. During one session, participants were experimentally intoxicated to obtain a blood alcohol concentration of at least 0.10%. During another session, a nonalcohol placebo was administered. The learning task consisted of a paired-associate paradigm requiring participants to learn the distinct spatial positions of 6 visually presented "nonsense shapes." The visuospatial learning of participants in the placebo condition was generally superior to their learning while intoxicated. However, intercorrelations of performance measures indicated that the relation between alcohol ingestion and performance differences across conditions was not linear.

Can caffeine antagonize alcohol-induced performance decrements in humans?

Design aspects and results of experiments that investigated the effects of caffeine on alcohol-induced performance decrements in humans are discussed. Simple conclusions concerning those outcomes are unwarranted because they seem to depend on the tasks used and the dosages of both drugs, with both antagonism and potentiation of alcohol-induced effects having been reported. Results indicate that legally intoxicated individuals cannot antagonize alcohol-induced, driving-related decrements with caffeine prior to driving an automobile, thought to be the major behavior for which caffeine is used in attempts to antagonize alcohol-induced decrements. We offer suggestions for research concerning subjects' habitual use or nonuse of caffeine and typical alcohol consumption levels, the interval between alcohol and caffeine ingestion, and the effects of caffeine and alcohol alone on performance tasks. We also suggest that statistical analyses should allow for a differentiation of results in which caffeine partially offsets an alcohol-induced decrement from more positive results in which caffeine returns functioning to its normal level.

Effect of meptazinol and ethanol on human psychomotor performance and mood ratings

The effect of meptazinol and/or ethanol on human psychomotor performance and mood ratings has been investigated in 8 healthy volunteers in a double blind randomised study. Meptazinol (200 mg 3 hourly for 4 doses) or placebo were administered orally and ethanol (0.8 g/kg) or placebo were given 30 min after the last tablet. Peak saccadic velocity (PSV), saccade duration at 30 degrees of amplitude (SD), smooth pursuit velocity (SPV), critical flicker fusion threshold (CFF), choice reaction time (CRT) and visual analogue scales were assessed. PSV (p less than 0.01), SD (p less than 0.001) and SPV (p less than 0.01) were significantly impaired after ethanol, while CFF, CFT and visual analogue scales showed no significant effect. None of the tests was affected by the meptazinol treatment alone. No changes were observed in the ethanol-induced impairment of PSV, SD and SPV when meptazinol was given in combination with ethanol.

Investigating drug--ethanol interactions

Methodology developed in our laboratories for testing the interactive effects of ethanol and drugs on human psychomotor performance is discussed. An attempt has been made to relate the findings of our studies to the results of real-life impairment, particularly in traffic crashes. Proposals for more comprehensive testing of drug--ethanol interactions have been put forward which may increase the predictive value of such tests.

Naloxone has no effect on ethanol-induced impairment of psychomotor performance in man

In a study designed to investigate the effect of naloxone on ethanol-induced performance deficits in man, ethanol (0.75 g/kg) and naloxone (0.4 mg) or saline were administered to 39 volunteers in a double-blind fashion. Psychomotor performance was assessed on a battery of tests (standing steadiness, pursuit rotor, simple and complex reaction times, a speeded number test and the Vienna Determination Apparatus) and blood and breath ethanol concentrations were monitored. Two experiments were performed: in Experiment 1 ethanol was given before naloxone and in Experiment 2 naloxone was administered before ethanol. There were no significant differences in either blood or breath ethanol concentrations at any time between the ethanol + naloxone and ethanol + saline groups in either Experiment 1 or 2. Although ethanol produced a significant decrement on most of the performance measures, naloxone was without effect. There was no suggestion of ethanol impairment being moderated by naloxone, whether it was given before or after ethanol.

Interaction between ethanol and antihistamines: 3. mebhydrolin

We used 17 student volunteers in an experiment to investigate the effects of orally administered mebhydrolin (0.71 mg/kg), alone and in combination with ethanol (0.75 g/kg), on perceptual, cognitive and motor functions. Mebhydrolin did not significantly modify performance when given alone, but showed evidence of enhancing ethanol-induced performance deficits. Histamine challenge experiments indicated that the dose of mebhydrolin used exerted an antihistaminic effect over the period of the ethanol interaction study.

Separate and combined effects of alcohol and tobacco on the amplitude of the contingent negative variation

To examine the separate and combined effects of alcohol and tobacco smoking on cortical functioning, the amplitude of the contingent negative variation (CNV) was studied during a simple reaction time task in non-smokers, tobacco-deprived smokers and non-deprived smokers in sessions involving administration of four cigarettes and/or 0.65 g/kg ethyl alcohol. Computer analysis indicated that alcohol and combined alcohol + tobacco significantly reduced the CNV amplitude in non-deprived smokers. Two sub-groups of non-smokers were identified, one showing large pre-drug CNV amplitudes and significant alcohol-induced reductions and the other showing small pre-drug amplitudes and no change in CNV amplitude after alcohol. No significant results were observed with alcohol, tobacco or alcohol + tobacco combined in tobacco-deprived smokers. The results are discussed in relation to previously reported studies which have indicated both synergistic and antagonistic interactions between alcohol and tobacco, and suggestions are forwarded regarding the experimental and clinical significance of tobacco-induced enhancement of CNV amplitude reduction by alcohol.

Acute effects of alcohol on saccadic eye movements

Four components of 20 degrees horizontal saccadic eye movements, i.e., latency, mean and maximum velocities, and duration were measured in 16 students under the influence of alcohol and also in a control situation. The experimental procedures were standardized and automated as much as possible. Latency (simple eye reaction time) was not influenced by alcohol in blood concentrations of 0.056--0.116%. Mean and maximum eye velocities decreased by about 9% and duration of saccades increased by 11%. The maximum changes occurred 90--120 min after the start of alcohol ingestion. The changes in velocities and durations correlated more closely with feelings of intoxication than with blood alcohol concentrations. There were great intra- and intersubject variations in reactions to alcohol. The close resemblance between the effects of certain psychotropic drugs, alcohol, fatigue, and decreased attention on eye movement control suggest that all these may act upon the same nervous structures in the brain stem.

The effect of (-) trans-delta9-tetrahydrocannabinol, alone and in combination with ethanol, on human performance

Twenty five volunteers received (-) trans-delta9-tetrahydrocannabinol (THC) (320 microgram/kg) or placebo (both orally, T0), and, 60 min later, they consumed an ethanolic beverage (0.54 g/kg) or placebo. The effects of this medication were measured at T1 (100 min after THC ingestion), T2 (160 min), T3 (220 min) and T4 (280 min) using a battery of cognitive, perceptual and motor function tests. Factorial analysis indicated that the test procedures could be adequately expressed by four rotated factors: a reaction speed factor (I'), a cognitive factor (II'), a standing steadiness factor (III') and a psychomotor coordination factor (IV'). The first principal component (I) was used as a measure of general performance across the whole test battery. Both THC and ethanol produced significant decrements in the general performance factor. Ethanol produced significant decrements in standing steadiness and psychomotor coordination, while THC caused a significant deterioration in performance on all the four rotated factors. In all cases the peak effect of ethanol occurred at T1 and by T4 the effect had worn off. The performance decrements induced by THC were slower in onset and lasted longer than those induced by ethanol. In general, the peak effect of THC occurred at T1 and T2. There was no evidence of any interaction between THC and ethanol, and the effects of a combination of THC and ethanol were no more than additive. THC (but not ethanol) produced a significant rise in pulse rate. Prior administration of THC did not significantly affect the blood ethanol levels obtained. The subjects were able to identify correctly which of the treatments they had received.

The interaction between ethanol and antihistamines: 2. Clemastine

Eighty paid student volunteers (35 male, 45 female) were used in an experiment to investigate the effects of a therapeutic dose of clemastine (1 mg) alone and in combination with a social dose of ethanol (0.54 g/kg) on perceptual, cognitive and motor functions. Both drugs were given orally. Clemastine did not significantly modify performance when given alone, and the performance decrements induced by ethanol were not enhanced by clemastine premedication.

Effects of alcohol on moral functioning in male social drinkers

The present study investigated the effect of alcohol consumption on both moral reasoning and moral values, cognitive variables which are likely to mediate moral behavior. Fifty-five male social drinkers (Mean age = 19.75 years) participated in a one-way pretest-posttest design incorporating two experimental (alcohol) and three control groups. Results showed that alcohol did not affect moral stage reasoning on the Defining Issues Test. However, the endorsement of meaningless items was significantly, but differentially, affected by the alcohol doses administered. No group differences were found in regard to moral values. These findings are related to previous research on alcohol and cognitive processes.

The interaction of fructose, dextrose and ethanol on human performance

1. The effects of orally administered fructose (1.2 g.kg-1) and dextrose (1.2 g.kg-1) on the performance decrement induced by ethanol (1.0 g.kg-1) in a series of perceptual, cognitive and motor tests were studied in twelve healthy, paid University student volunteers using a double-blind cross-over design. Ethanol was consumed at a constant rate over 20 min and the hexoses or placebo were given approximately 40 min later. 2. The peak blood ethanol concentration was attained earlier when the subjects also received either hexose than after placebo but although its rate of fall was unaffected, significantly lower ethanol concentrations were encountered in the hexose-treated groups in the latter part of the experiment. 3. In general, the subjects were impaired to a slightly lesser degree when they received a combination of hexose and ethanol than after ethanol alone. There were no differences between the effects of fructose and dextrose. 4. The results do not support contentions that fructose is able to accelerate a return to sobriety and observed differences between hexose and placebo-treated groups were attributed to an effect on the absorption of ethanol rather than its metabolism.

The effect of disodium cromoglycate on human performance, alone and in combination with ethanol

Seventeen paid volunteer subjects were used in a double-blind crossover experiment to investigate the effects of disodium cromoglycate (DSCG), alone and in combination with ethanol, on human perceptual, cognitive and motor performance. DSCG (40 mg) had little effect when given alone. When administered with ethanol (0-75 g/kg), DSCG did not significantly modify the ethanol-induced decrement in performance except in the complex reaction time test.