The effect of a moderate dose of alcohol on the traffic hazard perception profile of young drink-drivers1

Hazard perception latency has been identified as one source of individual differences in road accidents, but alcohol's effects on hazard perception has not been addressed thoroughly. Furthermore, individuals convicted of driving while impaired (DWI), in comparison with other drink-drivers, have been found to possess a poor driving record, suggesting that they may also respond poorly to hazards. Therefore, this research studied young drivers across the spectrum of drink-driving practices, from non drink-drivers to DWI offenders. It examined alcohol's effects on their hazard perception profile, including aspects of both driving skill (hazard perception latency) and driving style (the perceived level of risk in hazards). Thirty-two subjects aged 18-25 years underwent two experimental conditions in a counterbalanced design: no alcohol and moderate alcohol. Alcohol was found to affect both driving skill and driving style. With a 0.05% BAC subjects took longer to detect hazards and responded to them in a more abrupt manner and these effects were particularly pronounced for DWI offenders. The results also supported a distinction between active hazards (hazards arising from the driver's own actions) and passive hazards (hazards arising from the actions of other road users). Irrespective of their drink-driving practices, subjects perceived active hazards as less dangerous than passive hazards. Furthermore, compared with other drink-drivers, DWI offenders perceived less risk during passive hazards (with a 0.05% BAC) and active hazards (when sober). It is suggested that these effects may underlie, at least in part, the increase in accident risk associated with impaired driving.     

The effects of age and alcohol intoxication on simulated driving performance, awareness and self-restraint

AIMS: To investigate whether, compared with middle-aged men (aged 30-50), older men (age > or =60) (i) perform more poorly on a driving simulator and (ii) are more sensitive to the effects of ethanol in terms of blood alcohol concentration (BAC) and driving performance, but more aware of their driving difficulties, and therefore exercise better driving judgement. METHODS: 14 Healthy middle-aged men (mean age 36 years) were compared with 14 healthy older men (mean age 69 years) on an interactive driving simulator, while sober and while legally intoxicated (BAC >80 mg/dl). RESULTS: Older age was associated with poorer driving performance on the simulator. While sober, older men exhibited more improper braking, slower driving, greater speed variability, fewer appropriate full stops and more crashes, and spent more time executing left turns (across oncoming traffic); all values < or =0.02. BACs > or =80 mg/dl were associated with impaired driving, with more inappropriate braking, fewer appropriate full stops and more time executing left turns (all values > or =0.02) and trends towards more speed variability, more low speed collisions and more wrong turns (values <0.1). However, similar ethanol consumption did not produce higher peak BAC or more driving impairments in older drivers. While there were no differences between age groups in terms of awareness of intoxication or driving difficulties, older men were unwilling to drive while legally intoxicated because of fear of physical injury, whereas middle-aged men were more likely to avoid driving when intoxicated due to fear of legal ramifications. CONCLUSION: While both age and legal intoxication affected driving performance, older men were no more sensitive to ethanol in terms of peak BACs, driving performance or awareness/judgement than middle-aged men.     

Effects of alcohol on simulated driving and perceived driving impairment in binge drinkers

Background:  Binge drinking (heavy episodic alcohol use) is associated with high rates of impaired driving and myriad alcohol-related accidents. However, the underlying reasons for the heightened accident risk in this demographic group are not known. This research examined acute alcohol effects on simulated driving performance and subjective ratings of intoxication and driving ability in binge and nonbinge drinkers.
Methods:  Young social drinking college students (24 binge drinkers and 16 nonbinge drinkers) participated in this study. Participants attended a session during which they received a moderate dose of alcohol (0.65 g/kg) and a session during which they received a placebo. A simulated driving task measured participants' driving performance in response to each dose. Subjective responses to each dose were also assessed, including ratings of sedation, stimulation, and driving ability.
Results:  The acute dose of alcohol impaired multiple aspects of driving performance in both binge and nonbinge drinkers. Under alcohol, all participants had greater difficulty in maintaining their lane position, maintaining the appropriate speed and made multiple driving errors compared to placebo performance. By contrast, compared with nonbinge drinkers, binge drinkers reported feeling less sedated by the alcohol and reported having a greater ability to drive following the acute dose of alcohol.
Conclusions:  Reduced subjective intoxication and perceived driving impairment in binge drinkers may account for the greater accident risk in this demographic group. Binge drinkers may lack the internal sedation cue that helps them accurately assess that they are not able to effectively drive a vehicle after drinking.     

Developing limits for driving under cannabis

OBJECTIVE: Development of a rational and enforceable basis for controlling the impact of cannabis use on traffic safety. METHODS: An international working group of experts on issues related to drug use and traffic safety evaluated evidence from experimental and epidemiological research and discussed potential approaches to developing per se limits for cannabis. RESULTS: In analogy to alcohol, finite (non-zero) per se limits for delta-9-tetrahydrocannabinol (THC) in blood appear to be the most effective approach to separating drivers who are impaired by cannabis use from those who are no longer under the influence. Limited epidemiological studies indicate that serum concentrations of THC below 10 ng/ml are not associated with an elevated accident risk. A comparison of meta-analyses of experimental studies on the impairment of driving-relevant skills by alcohol or cannabis suggests that a THC concentration in the serum of 7-10 ng/ml is correlated with an impairment comparable to that caused by a blood alcohol concentration (BAC) of 0.05%. Thus, a suitable numerical limit for THC in serum may fall in that range. CONCLUSIONS: This analysis offers an empirical basis for a per se limit for THC that allows identification of drivers impaired by cannabis. The limited epidemiological data render this limit preliminary.     

Impact of diabetes mellitus on driving safety

Driving ability is controlled by specific regulations. Therefore disabled individuals or those with certain chronic diseases may be affected by these regulations. These latter are based on assumption that the existence and the nature of certain diseases may cause particular hazard; and this could be prevented by introducing certain driving regulations. This hypothesis has not been tested properly, considering the proposed and suspected risk factors. Diabetes mellitus is a good example of the interested medical condition in this field. Review of the literature do not provide adequate information to allow us to conclude whether the insulin treated diabetic person is at higher risk to develop traffic accident, compared with non diabetic individual; and there is no definite explanation whether hypoglycaemia play a causative role in the etiology of traffic accident among insulin treated diabetics. Perhaps the lack of knowledge in this field is due to use of non-standardized methodologies and small sample size studies which make the comparisons difficult. The existing regulations in different countries are based on empirical knowledge and common sense. This often leads to conflictual situations and apparently discriminatory decisions regarding diabetics. Further comparative and prospective studies are needed.     

The effectiveness of a 0.05 blood alcohol concentration (BAC) limit for driving in the United States

The National Transportation Safety Board recently recommended that states establish a per se blood alcohol concentration (BAC) limit of 0.05 or lower for all drivers who are not already required to adhere to lower BAC limits in a national effort to reduce alcohol‐impaired driving. There is strong evidence for adopting this recommendation. A comprehensive review of the literature on BAC limits was conducted. The research indicates that virtually all drivers are impaired regarding at least some driving performance measures at a 0.05 BAC. The risk of being involved in a crash increases significantly at 0.05 BAC and above. The relative risk of being killed in a single‐vehicle crash with BACs of 0.05–0.079 is 7–21 times higher than for drivers at 0.00 BAC. Lowering the BAC limit from 0.08 to 0.05 has been a proven effective countermeasure in numerous countries around the world. Most Americans do not believe a person should drive after having two or three drinks in 2 hours. It takes at least four drinks for the average 170‐pound male to exceed 0.05 BAC in 2 hours (three drinks for the 137‐pound female). Most industrialized nations have established a 0.05 BAC limit or lower for driving. Progress in reducing the proportion of drivers in fatal crashes with illegal BACs has stalled over the past 15 years. Lowering the BAC limit for driving from the current 0.08 to 0.05 has substantial potential to reduce the number of people who drink and drive in the United States and get involved in fatal crashes.     

Behavioural correlates of alcohol intoxication

Alcohol is used in most cultures despite knowledge of the physical, psychological and social problems associated with its abuse. Behavioural impairment is a function of several factors, including blood alcohol concentration (BAC) and the rate of alcohol metabolism by alcohol dehydrogenase and the microsomal ethanol-oxidizing system. Their availability and activity depend upon alcohol use history, ethnicity, other drug use and gender. Adverse social consequences related to alcohol intoxication include impaired driving, acts of aggression and violence towards self and others, and various types of accidents. About 40% of all fatal traffic accidents in Canada and the US in 1986-1987 were alcohol-related. Similar statistics have been reported in the UK and Europe (e.g. Sweden). The risk of a fatal car accident increases exponentially with a driver's BAC, prompting recommendations to lower the legal BAC limit for driving and piloting aircraft. Risks of falls, drownings, and fires and bums may also be increased by alcohol intoxication. At least 22% of work-related accidents may have involved alcohol use. These data are probably conservative estimates as under-reporting of alcohol use is likely. Alcohol facilitates aggressive behaviours, but it is difficult to separate the pharmacological effect from psychosocial effects or some other common factor (e.g. low CSF levels of the serotonin metabolite 5-H1AA have been reported in alcoholics, suicide attempters, violent offenders). In addition, alcohol interacts with other drugs to increase or decrease their behavioural and therapeutic effects. An acutely high BAC inhibits the metabolism of other CNS depressants (e.g. benzodiazepines), but long-term alcohol use increases the metabolism of most drugs. A potential amethystic agent, to block or reverse alcohol's effects, has been identified in preclinical studies (Ro15-4513, an imidazobenzodiazepine). Some clinical studies indicated that naloxone, lithium, ibuprofen, zimeldine and catecholamine agonists may reduce ethanol-induced behavioural or cognitive effects but the results have not been consistently replicated. More research is needed to determine the potential clinical use of amethystic agents and other pharmacotherapies in the prevention and treatment of problem behaviours associated with alcohol abuse and intoxication.     

Automobile driving and implantable defibrillators

The consequences of implanting an automatic cardioverter defibrillator (ICD) on vehicle driving in France are poorly known. This retrospective study examined the behaviour at the wheel of ICD recipients who were recommended to abstain from driving for 3 to 6 months after device implantation. The study population included 98 patients (mean age = 59.5 +/- 14.8 years) followed for a mean of 24. +/- 23.9 months, who underwent ICD implant for ventricular tachycardia (65% of patients ventricular fibrillation (15%), syncope (8%), as part of a research protocol of myocardial cell transplantation 6%, or for primary prevention (5%). The underlying heart disease was ischemic in 59% of patients dilated cardiomyopathy in 11%,hypertrophic cardiomyopathy in 8%, valvular in 6%. Brugada syndrome in 4%, right ventricular arrhythmogenic cardiomyopathy in 2%, and miscellaneous disorders in 9% of patients. Five patients died without post mortem interrogation of the ICD. Only 28% of drivers remembered, and 13% observed, the recommended driving limitations. However, 45% (the oldest) claimed to drive prudently. During follow-up, 47% of patients received an ICD shock. Their mean it ventricular ejection fraction was 34 +/- 14%, versus 43 +/- 18% in patients who received no ICD therapy (p = 0.015). Syncope occurred in 16% who received ICD shocks. Shocks were delivered during driving in 6 patients, without consequent accident. Despite their non-observance of recommended driving limitations. ICD recipients suffered few traffic accidents. Legislation in France should reproduce the guidelines issued by European professional societies and enacted by the British laws.     

The relationship between serious injury and blood alcohol concentration (BAC) in fatal motor vehicle accidents: BAC = 0.01% is associated with significantly more dangerous accidents than BAC = 0.00%

Aim To analyze the severity of automotive injuries associated with blood alcohol concentration (BAC) in increments of 0.01%. Design/setting Epidemiological study using the Fatality Analysis Reporting System. Participants All people in US fatal automotive accidents, 1994–2008 (n = 1 495 667). Measurements The ratio of serious: non‐serious injuries for drivers, by BAC. Findings Accident severity increases significantly even when the driver is merely ‘buzzed’, a finding that persists after standardization for various confounding factors. Three mechanisms mediate between buzzed driving and high accident severity: compared to sober drivers, buzzed drivers are significantly more likely to speed, to be improperly seatbelted and to drive the striking vehicle. In addition, there is a strong ‘dose–response’ relationship for all three factors in relation to accident severity (e.g. the greater the BAC, the greater the average speed of the driver and the greater the severity of the accident). Conclusions The severity of life‐threatening motor vehicle accidents increases significantly at blood alcohol concentrations (BACs) far lower than the current US limit of 0.08%. Lowering the legal limit could save lives, prevent serious injuries and reduce financial and social costs associated with motor vehicle accidents.     

The joint association of average volume of alcohol and binge drinking with hazardous driving behaviour and traffic crashes

BACKGROUND: Previous studies on alcohol-related road safety have not assessed the joint impact of average volume of alcohol and binge drinking. AIM: To examine the joint and separate association of average volume of alcohol and binge drinking with hazardous driving behaviour and traffic crashes. METHODS: Data were drawn from telephone interviews conducted in the period 2000-2005, with 12 037 individuals representative of the population aged 18-64 years in the Madrid region, Spain. The threshold between average moderate and heavy volumes was 40 g of alcohol/day in men and 24 g/day in women. Binge drinking was defined as intake of >or= 80 g of alcohol in men and >or= 60 g in women, during any drinking occasion in the preceding 30 days. Individuals were classified into the following categories: (i) non-drinkers; (ii) moderate drinkers with no binge drinking (MDNB); (iii) moderate drinkers with binge drinking (MDB); (iv) heavy drinkers with no binge drinking (HDNB); and (v) heavy drinkers with binge drinking (HDB). Analyses were performed using logistic regression, with adjustment for sex, age and educational level. FINDINGS: Frequency of inadequate seat-belt use increased progressively across categories of alcohol consumption, with odds ratio (OR) 1 in non-drinkers, 1.19 [95% confidence interval (CI) 1.06-1.33] in MDNB, 1.69 (1.41-2.03) in MDB, 1.68 (1.24-2.29) in HDNB and 2.41 (1.83-3.18) in HDB (P for trend <0.001). Compared with MDNB, alcohol-impaired driving was also more frequent in MDB (OR 7.43; 95% CI: 5.52-10.00), HDNB (OR 7.31; 95% CI: 4.37-12.25) and in HDB (OR 15.50; 95% CI: 10.62-22.61). Lastly, compared with non-drinkers, frequency of traffic crashes increased progressively across categories of alcohol consumption (P for trend=0.028), although it only reached statistical significance in HDB (OR 2.01; 95% CI: 1.00-4.09). CONCLUSIONS: Self-reported average volume of alcohol and binge drinking are both associated with self-reported hazardous driving behaviour and traffic crashes. The strength of the association is greater when average heavy consumption and binge drinking occur jointly.     

Daidzin, an Antioxidant Isoflavonoid, Decreases Blood Alcohol Levels and Shortens Sleep Time Induced by Ethanol Intoxication

The extract from an edible vine, Pueraha lebata has been reported to be efficacious in lessening alcohol intoxication. In this study, we have tested the efficacy of one of the major components, daidzin, from this plant extract. When ethanol (40% solution, 3 g/kg body weight) was given to fasted rats intragastrically, blood alcohol concentration (BAC) peaked at 30 min after alcohol ingestion and reached 1.77 ± 0.14 mg/ml (mean values ±sd , n = 6). If daidzin (30 mg/kg) was mixed with the ethanol solution and given to animals intragastrically, BAC was found to peak at 90 min after alcohol ingestion and reached only 1.20 ± 0.30 mg/ml (n = 6) (p < 0.05 vs. controls). The ability of daidzin to delay and decrease peak BAC level after ethanol ingestion was also observed in fed animals, in both fasted and fed rats given alcohol without daidzin, BAC quickly declined after reaching its peak at 30 min. By contrast, BAC levels receded more slowly if daidzin was also fed to the animals. Daidzin showed a chronic effect. Rats fed daidzin for 7 days before ethanol challenge, but not on the day of challenge, also produced lower and later peak BAC levels. Interestingly, daidzin, whether fed to rats only once or chronically for 7 days, did not significantly alter activities of either alcohol dehydrogenase or mitochondrial aldehyde dehydrogenase in the liver. Further experiments demonstrated that daidzin shortened sleep time for rats receiving ethanol intragastrically (7 g/ kg) but not intraperitoneally (2 g/kg). To test whether daidzin delayed stomach-emptying, [Clpolyethylene glycol was mixed with ethanol and fed to rats. It was found that, 30 min after intragastric feeding, more ethanol and [¹⁴C]polyethylene glycol remained in the stomach if rats were also given daidzin. Because daidzin is an isoflavonoid glucoside that possesses strong antioxidant activity, two other antioxidants (i.e., vitamin E and thioctic acid) were tested. Similar to daidzin, these two antioxidants also delayed and suppressed peak BAC, as well as shortened sleep time induced by alcohol ingestion. We conclude that: (1) daidzin is effective in countering alcohol intoxication; (2) suppression of BAC by daidzin is due mainly to delay of stomach-emptying, but not to accelerated clearance of ethanol in circulation by liver enzymes; and (3) the effect of daidzin may in part be due to its antioxidant activity.     

Self-reported sleepiness while driving as a risk factor for traffic accidents in patients with obstructive sleep apnoea syndrome and in non-apnoeic snorers

The obstructive sleep apnoea syndrome (OSAS) is a condition causing daytime sleepiness and has been related to an increased risk for traffic accidents. However, the evidence linking severity of OSAS to a higher rate of automobile crashes is based on limited data. The aims of this study were to study the traffic accident rate in the last 5 years in patients referred to our sleep clinic because of clinical suspicion of OSAS and to analyse variables related to an increased risk for traffic accidents. A series of 189 consecutive patients with a driving license referred for a sleep study because of OSAS clinical suspicion and a control group (CG) of 40 hospital staff workers who denied snoring, matched for age and sex with the study population, were studied. Patients underwent a full-night polysomnography and both patients and the CG completed a self-answered questionnaire. One hundred and twenty-two patients were diagnosed as OSAS and 67 patients as non-apnoeic snorers (NAS). The self-reported number of accidents was significantly higher in OSAS patients compared with CG. The self-reported number of times off the road was significantly higher in OSAS patients compared with NAS and with CG. Variables associated with an increased risk for traffic accidents were self-reported sleepiness while driving (OR 5, 95%CI 2.3-10.9), having quit driving because of sleepiness (OR 3, 95%CI 1.1-8.6) and being currently working (OR 2.8, 95%CI 1.1-7.7). We conclude that self-reported sleepiness while driving is associated with an increased risk for traffic accidents in OSAS patients and in NAS. We suggest that this symptom can be used to alert patients and to give priority in the sleep clinic for study and treatment.     

Acute Alcohol Exposure and Risk of Mortality of Patients with Traumatic Brain Injury: A Systematic Review and Meta‐Analysis

After traumatic brain injury (TBI), patients usually live with significant disability and socioeconomic burdens. Acute exposure to alcohol is considered a major risk factor for TBI. Numerous studies have examined whether alcohol exposure is related to the risk of mortality in patients with TBI, yet the results remain inconsistent. We performed a meta‐analysis to assess whether acute alcohol exposure affects the mortality rate of TBI patients. We searched PubMed, EMBASE, and the Cochrane Library up to November 2015 for relevant studies. We screened studies based on their inclusion criteria and selected the studies that reported mortality rate, which included 18 observational studies. We used R to analyze the included data. An initial result showed that the presence of a positive blood alcohol concentration (BAC) had no significant relation with mortality rate (OR = 0.92, 95% CI = 0.83 to 1.01), but there was notable heterogeneity along with variable results according to sensitivity analysis. For the BAC‐positive population, low BAC (1 to 100 mg/dl) carried a higher risk of mortality than moderate BAC (100 to 230 mg/dl) (OR = 1.40, 95% CI = 1.09 to 1.81), moderate and high BAC as a single category (>100 mg/dl) (OR = 1.57, 95% CI = 1.28 to 1.94), or high BAC (>230 mg/dl) (OR = 1.76, 95% CI = 1.34 to 2.30). However, moderate BAC did not increase the mortality risk when compared with high BAC (OR = 1.20, 95% CI = 0.89 to 1.63). Whether positive BAC at the time of admission after TBI reduces mortality rate compared with the rate under negative BAC remains unknown. In addition, low BAC (1 to 100 mg/dl) poses a risk of mortality compared with higher BAC. Further studies assessing the effect of alcohol between the BAC‐positive group and the BAC‐negative group are still needed.     

Attitudes to driving among patients with diabetes mellitus in Punjab (ADD-Punjab study)

AimCurrently there are no regulations regarding diabetes and driving licensing in India. The study was planned to gather information about attitudes to driving among patients with diabetes mellitus.MethodsAdult patients with diabetes mellitus holding a current valid driving license on treatment with insulin or secretagogue were interviewed using a validated structured questionnaire.Results150 patients were interviewed with a mean age of 52 years, males (86%), insulin users (34%) and only secretagogue users (66%). 16 (10.6%) patients had severe hypoglycemia in the past year with 9.3% having hypoglycemic unawareness. Only 32% patients were aware of the relation between hypoglycemia and driving, 88.6% never checked glucose prior to driving and only 23% patients carried carbohydrates for treatment of hypoglycemia during driving. 25 (16.7%) of subjects had hypoglycemia during driving and in 6 (4%) this involved a traffic accident in the past one year.ConclusionsAround 4% of patients on hypoglycemia causing treatment have a traffic accident/event every year. In the absence of regulations currently, focus should be on patient education. However, on the long-term appropriate regulations will make the roads safer for patients with diabetes.     

Comparison of the effects of sleep deprivation, alcohol and obstructive sleep apnoea (OSA) on simulated steering performance.

Patients with obstructive sleep apnoea (OSA) are reported to have an increased risk of road traffic accidents. This study examines the nature of the impairment during simulated steering in patients with OSA, compared to normal subjects following either sleep deprivation or alcohol ingestion. Twenty-six patients with OSA and 12 normal subjects, either deprived of one night's sleep or following alcohol ingestion [mean (SD) alcohol blood level 71.6 mg dl(-1) (19.6)], performed a simulated steering task for a total of 90 min. Performance was measured using the tendency to wander (SD), deterioration across the task, number of 'off-road' events and the reaction time to peripheral events. Control data for OSA, sleep deprivation and alcohol were obtained following treatment with nasal continuous positive airway pressure (nCPAP), after a normal night of sleep, and following no alcohol, respectively. Patients with untreated OSA, and sleep-deprived or alcohol-intoxicated normal subjects performed significantly less well, compared to their respective controls (P<0.01 for all tests), with untreated OSA lying between that of alcohol intoxication and sleep deprivation. Alcohol impaired steering error equally throughout the whole drive, whilst sleep deprivation caused progressive deterioration through the drive, but not initially. Untreated OSA was more like sleep deprivation than alcohol, although there was a wide spread of data. This suggests that the driving impairment in patients with OSA is more compatible with sleep deprivation or fragmentation as the cause, rather than abnormal cognitive or motor skills.     

Fast, but error-prone, responses during acute alcohol intoxication: effects of stimulus-response mapping complexity

BACKGROUND: Although moderate doses of alcohol can impair performance on tasks that require information processing, little is known about the locus of the alcohol effects within the processing stream. This study used a psychological refractory period paradigm to investigate the effect of alcohol on the central, cognitive stage of information processing when task complexity is manipulated by altering stimulus-response compatibility. METHODS: Thirty-four healthy male social drinkers were assigned to one of two groups (n = 17) that performed two tasks. Each trial consisted of a task 1 stimulus (tone) followed by a task 2 stimulus (letter) that was presented after one of four stimulus onset asynchronies (50, 200, 500, or 1100 msec). A baseline test of performance was obtained before the groups received a beverage containing either 0.0 g/kg (placebo) or 0.65 g/kg alcohol. Both groups were retested when blood alcohol concentration (BAC) was increasing and was decreasing. RESULTS: The alcohol group made significantly more errors in task 1 compared with their drug-free baseline measure during the ascending phase of the BAC curve, and error rates increased to a greater extent for the more complex arbitrary stimulus-response mapping condition. Moreover, this increase in errors continued unabated during the descending phase of the BAC curve. Increasing BACs also slowed performance (longer reaction time), but unlike errors, reaction time returned to drug-free baseline levels when BAC was decreasing. CONCLUSIONS: The results provide evidence that an acute dose of alcohol can impair one aspect of the central, cognitive stages of information processing. The possibility that errors in information processing remain during decreasing BACs even after processing speed has returned to drug-free levels has important practical implications relating to the detrimental consequences of acute alcohol intoxication.     

Effects of a moderate evening alcohol dose. II: performance

BACKGROUND: This second of a pair of papers investigates the effects of a moderate dose of alcohol and staying up late on driving simulation performance and simple visual reaction time (RT) at a known circadian phase in well-rested young adults. METHODS: Twenty-nine adults (9 males), ages 21 to 25 years, spent 1 week on an at-home stabilization schedule of 8.5 to 9 hours, followed by 3 nonconsecutive nights in-lab: adaptation, placebo, and alcohol. Performance task practice occurred on 3 occasions before the study. Alcohol (vodka; 0.54 g/kg men; 0.49 g/kg women mixed with tonic) was consumed over 30 minutes ending 1 hour before normal bedtime; the same quantity of beverage was given on placebo. Driving simulation (with drive-only and dual-task drive and subtract components) and psychomotor vigilance task (PVT) testing occurred before and after alcohol/placebo ingestion. Breath alcohol concentration (BrAC) readings were taken before all test sessions. Saliva samples were taken approximately every 30 minutes to determine circadian phase. RESULTS: Driving simulation and PVT variables significantly deteriorated with increasing time awake. Driving simulator lane variability was worse with alcohol compared with placebo at 15.5 hours awake. No PVT variable showed an effect of alcohol. CONCLUSIONS: Driving simulation performance deteriorated with extended waking and with alcohol; driving was most impaired at the peak alcohol level. The PVT, less complex than the driving simulation, did not show effects of alcohol, a finding consistent with previous literature that disruptive effects of low alcohol concentrations increase with task complexity. Overall, simulated driving performance is significantly impaired late at night when even a moderate dose of alcohol is consumed.     

Beginnende Demenz und Fahreignung

Physiological changes, but most of all diseases, affect driving ability in old age, whereby cognitive and mental performance plays an important part. Impaired health and feeling of unease while driving are the main reasons for driving cessation in the elderly. The causes of crashes and crash development show typical features compared to younger drivers. In the assessment of accident frequency and crash risk, sophisticated analyses are necessary. A person with moderate to severe dementia is certainly no longer fit to drive, whereas driving ability may be maintained in mild dementia for some time. In part 2, comprehensive information on the practice of assessment and judgement of driving ability is provided.     

Changes in Blood Alcohol Levels as a Function of Alcohol Concentration and Repeated Alcohol Exposure in Adult Female Rats: Potential Risk Factors for Alcohol-Induced Fetal Brain Injury

Fetal alcohol syndrome and alcohol-related birth defects are the result of heavy maternal alcohol consumption during gestation. The magnitude of deficit manifested by the offspring is invariably a consequence of several risk factors that may result in high peak blood alcohol concentrations (BACs), such as the duration, timing, or pattern of alcohol consumption. In addition, the alcohol content of the consumed beverage may play a role in determining offspring developmental consequences. Because higher BACs are positively correlated with risk and severity of brain injury early in postnatal lie, initially it was important to determine how BAC is influenced by alcohol concentration and whether that influence is constant over repeated alcohol treatments. Groups of female Sprague-Dawley rats received daily intragastric intubations of 5 g/kg alcohol in one of several concentrations: 45% (v/v), 30% (v/v), 22.5% (v/v), or 15% (v/v) for a duration of 18 consecutive days. Blood samples were taken at various times postintubation on days 3,8,13, and 18 of treatment, and analyzed by headspace gas chromatography. Multivariate analyses of peak BAC, average BAC, and time to reach peak BAC revealed some noteworthy results. First, peak BAC and average BAC were significantly lower in the 45% group, compared with the other concentration groups, whereas this group also took a longer time to reach peak BAC than the other three groups. Second, peak BAC and averege BAC were higher on the last day of treatment than any of the other treatment days. These results suggest that alcohol concentration and repeated alcohol exposure can influence BAC and, as such, are important risk factors to be considered in the appraisal of alcohol-induced fetal brain injuries.