Alcohol and the cognitive aspects of choice reaction time

Intoxication is a Significant Risk Factor for Severe Craniomaxillofacial Injuries in Standing Electric Scooter Accidents

PURPOSE

Standing electric scooters are a relatively new mode of transportation that are becoming increasingly popular in large metropolitan areas. The purpose of this study was to characterize injury patterns and identify risk factors for craniomaxillofacial injuries in standing electric scooter accidents.

METHODS

This retrospective cohort study used a Clinical Data Warehouse search engine to identify patients who sustained standing electric scooter accidents from 2017 to 2019 using the International Classification of Diseases 10th revision codes. Predictors including patient demographics, presence of intoxication, helmet use, mechanism of injury, and other noncraniomaxillofacial injuries sustained at the time of standing electric scooter injury were identified. Patients were grouped as per the presence or absence of craniomaxillofacial injuries so that risk factors could be identified for craniomaxillofacial injuries in standing electric scooter accidents. Logistic regression analysis was performed to identify potential risk factors and association for craniomaxillofacial injuries.

RESULTS

The sample was composed of 165 patients with a mean age of 30.3 years and 73.9% were men. Of them, 38 (23.0%) sustained craniomaxillofacial trauma. They were ten times more likely to have been intoxicated than those who did not have craniomaxillofacial injuries (4.7 vs 52.6%). Concomitant injuries of the extremities and the craniomaxillofacial region were rare indicating that in many cases the arms and legs were not outstretched to "break the fall." The high numbers of mandibular fractures to the condylar, subcondylar, and symphyseal regions (23.8, 33.3, and 28.6%, respectively), Le Fort fractures (18.4%), and frontal sinus fractures (15.8%) indicate that falls in the anterior-posterior direction occur with the main point of impact occurring at the chin, midface, and forehead.

CONCLUSIONS

Intoxication may inhibit or depress protective reflexes that leave the face and head vulnerable during standing electric scooter accidents.

Functional biomarkers for the acute effects of alcohol on the central nervous system in healthy volunteers

The central nervous system (CNS) effects of acute alcohol administration have been frequently assessed. Such studies often use a wide range of methods to study each of these effects. Unfortunately, the sensitivity of these tests has not completely been ascertained. A literature search was performed to recognize the most useful tests (or biomarkers) for identifying the acute CNS effects of alcohol in healthy volunteers. All tests were grouped in clusters and functional domains. Afterwards, the effect of alcohol administration on these tests was scored as improvement, impairment or as no effect. Furthermore, dose-response relationships were established. A total number of 218 studies, describing 342 different tests (or test variants) were evaluated. Alcohol affected a wide range of CNS domains. Divided attention, focused attention, visuo-motor control and scales of feeling high and of subjective drug effects were identified as the most sensitive functional biomarkers for the acute CNS effects of alcohol. The large number of CNS tests that are used to determine the effects of alcohol interferes with the identification of the most sensitive ones and of drug-response relationships. Our results may be helpful in selecting rational biomarkers for studies investigating the acute CNS effects of alcohol or for future alcohol- interaction studies.

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.

Correlation between the amplitude of cortical activation and reaction time: a functional MRI study

OBJECTIVE

We sought to examine the correlation between reaction time and the amplitude of cortical activation during the performance of a visuomotor response-time task in a functional MRI (fMRI) experiment. We hypothesized that the fMRI blood oxygenation level-dependent (BOLD) amplitude may have a negative correlation with a subject's reaction time: the lower the amplitude within the cortical areas along the visuomotor pathway, the slower the response. A larger amplitude of the fMRI signal would reflect faster response times.

SUBJECTS AND METHODS

During a single-event fMRI experiment, the reaction times (in milliseconds) of 32 right-handed subjects responding to a visual cue were recorded. Analysis of the single-event paradigm using Statistical Parametric Mapping (SPM99) was performed, activation maps were produced for each subject, and then a random effects group analysis was performed. The maximum amplitudes of cortical activation (percent signal change) in four activated cortical regions were estimated and tabulated. The regions of interest included were the right and left occipital visual cortices, the supplementary motor area, and the left sensorimotor area. Simple and multiple regressions were performed between the mean reaction times of the subjects and the BOLD amplitudes in each region of interest and for the composite region of interest.

RESULTS

The results showed significant negative associations between the reaction times and maximum amplitudes in the right occipital, left occipital, and left sensorimotor area cortical regions (p < 0.05). However, no significant association was found between reaction times and the amplitude within the supplementary motor area. When the effects of age and sex on these associations were analyzed, we found that age had an impact on the results for individual regions of interest in the left occipital and left sensorimotor areas, but the composite amplitude of activation remained significantly correlated with reaction times.

CONCLUSION

The degree of signal change in BOLD fMRI response of the right occipital, left occipital, and left sensorimotor areas reflects the speed of performance during the visuomotor response time task by the subject. Thus, the amplitude of activation can be used as one parameter to assess change in function.

Correlation of functional MR imaging activation data with simple reaction times

PURPOSE

To determine the relationship between subject reaction times (RTs) and activation volume in the brain during visuomotor functional magnetic resonance (MR) imaging.

MATERIALS AND METHODS

Twenty-four subjects performed a simple RT task during single-event functional MR imaging, and RTs were recorded. The six subjects with the fastest RTs were designated the fast RT group, and the six subjects with the slowest RTs were designated the slow RT group. The data were processed with noncorrected height threshold (P <.001) for individual comparisons and corrected height threshold (P <.05) for group comparisons (t tests). The activation volumes in both occipital lobes, the left sensorimotor cortex, and the supplemental motor cortices were compared for the two groups.

RESULTS

The mean RT +/- SD was 342 msec +/- 20.15 for the fast RT group and 475 msec +/- 36.17 for the slow RT group (P <.0001). More voxels of activation were seen in the fast RT group than in the slow RT group in the occipital lobes, left sensorimotor cortices, and supplemental motor cortices on individual and group maps. This difference was statistically significant in the left sensorimotor (P =.03) and left visual (P =.05) cortices. In the right visual cortex, a trend toward more activation in the fast RT group was noted (P =.15). There was a negative correlation between RTs and activation volume in the left sensorimotor cortex (P =.048).

CONCLUSION

There was a greater activation volume in motor and visual cortices in the fast RT group than in the slow RT group.

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.

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.

Effects of ethanol on human fractionated response times

The effects of ethanol (EtOH) on response components varying along a central vs. peripheral dimension were studied in five subjects. Reaction times (RTs) were fractionated by electromyographical recordings into premotor (central) and motor (peripheral, contractile) components. Highly practiced subjects performed a simple and discrimination RT task and related movement without significant impairment at the moderate blood ethanol concentration (BEC) (0.10%). At the higher BEC (0.17%), all components involving central processing (response time, RT and premotor time) were impaired in both simple and discrimination RT. More peripheral components (contractile time and movement time) were little affected. Contractile time was slowed slightly but significantly, but only in the combination of EtOH and the discrimination task which suggests that the stimulus discrimination stage of information processing can influence the activation of motor units involved in carrying out the movement.