Effects of alcohol intoxication on driving performance, confidence in driving ability, and psychomotor function: a randomized, double-blind, placebo-controlled study.

RATIONALE: Alcohol-induced driving impairment can occur with any departure from a zero-blood alcohol concentration (BAC). Because intoxication is characterised by impaired judgement, drivers under the influence of alcohol may overestimate their capacity to safely operate a vehicle. OBJECTIVES: This study examined the effects of alcohol on driving performance, four-choice reaction time (FCRT), and self-rated confidence in driving ability. It specifically focused on alcohol doses equal to commonly enforced legal BAC limits (i.e. 0.05% and 0.08%). METHODS: A randomized, double-blind, placebo-controlled design was utilised. Seventeen participants were tested in three conditions: placebo and two alcohol conditions aiming for BACs of 0.05% and 0.08%. Participants underwent a baseline FCRT task and a 1-h simulated highway driving task before completing another FCRT task and rated their confidence in their driving ability. RESULTS: The high and low alcohol dose conditions resulted in a mean BAC of 0.07%, and 0.04%, respectively (n = 17). The high BAC treatment significantly increased standard deviation of lateral position (SDLP) by 4.06 ± 5.21 cm and standard deviation of speed (SDS) by 0.69 ± 0.17 km/h relative to placebo, while confidence in driving ability remained unchanged across treatments. FCRT performance was impaired by the high BAC treatment (all < 0.01), but there we no significant differences between placebo and low BAC conditions. CONCLUSIONS: The findings of this study show that driving performance and associated psychomotor functioning become significantly impaired below legally permissible driving limits in some jurisdictions. We identified a dissociation between driving performance and subjective awareness of impairment. Despite a significantly diminished driving ability at 0.07% BAC, drivers were unaware of their impairment.

Effects of alcohol hangover on attentional resources during a verbal memory/psychomotor tracking dual attention task.

BACKGROUND: Alcohol hangover (AH) is associated with impaired attention and memory performance. However, whether this effect is related to reduced attentional resources remains unclear. AIMS: A dual-attention paradigm was employed to assess the effects of AH on attentional resources, delayed memory recognition, and the interaction between attentional load and AH. Mental effort and perceived performance during AH and control conditions were also assessed. METHODS: A seminaturalistic, crossover design was used. In total, 25 healthy social drinkers aged 18-35 years, visited the laboratory following a typical night out drinking (Hangover condition) and after alcohol abstinence (control) between 8:30 am and 12:30 pm, with conditions counterbalanced. Attentional load was manipulated via the presence (dual attention) or absence of psychomotor tracking during verbal memory encoding. Perceived mental effort and performance were measured using the NASA-TLX. Participants' recollected alcohol consumption was used to compute estimated blood alcohol level (eBAC). RESULTS: Compared with the control visit, AH was associated with reduced recognition accuracy (particularly more false negatives), higher "tracking costs" (poorer accuracy) in the dual attention condition, increased ratings of "mental demand," "effort," and "frustration," and lower ratings of task performance. There was also a significant main effect of attentional load with poorer recognition accuracy and response time in the dual attention condition. There were no significant interaction effects between hangover and attentional load. CONCLUSION: These findings suggest that reduced attentional resources contribute to the cognitive deficits associated with AH including impaired memory consolidation. They further suggest that while hungover, participants are aware of these deficits but are unable to compensate.

The effects of alcohol intoxication on cognitive functions critical for driving: A systematic review.

Alcohol is the most frequently detected substance in drivers involved in road traffic collisions. Given that up to 35% of fatal road collisions are alcohol-related, it is important to determine the influence of alcohol intoxication on driving-related skills. This review provides an updated and systematic evaluation of the available research concerning the effect of alcohol intoxication on cognitive functions critical for driving. Databases EBSCOhost, PsycInfo, PubMed, Scopus, Transport Research International Documentation (TRID) and Web of Science were searched for controlled trials examining the effect of alcohol on divided attention, executive functioning, perception, psychomotor skills, reaction time and/or vigilance. Fourteen studies met the inclusion criteria and were included in this review. We found that each of the cognitive domains assessed in this review showed impairment at blood alcohol concentrations equal to or below the legal driving limit in many jurisdictions. Future research could determine the effects of alcohol on cognitive functioning with greater accuracy by employing more consistent, reliable and comparable measures while considering the translation of deficits to real-life driving.

Alcohol Hangover and Multitasking: Effects on Mood, Cognitive Performance, Stress Reactivity, and Perceived Effort.

The aim of this study was to examine the effects of hangover on mood, multitasking ability, and psychological stress reactivity to cognitive demand. Using a crossover design and semi-naturalistic methodology, 25 participants attended the laboratory in the morning following a night of (i) alcohol abstinence and (ii) alcohol self-administration during a typical night out (with order counterbalanced across participants). They completed a four-module multitasking framework (MTF, a widely used laboratory stressor) and a battery of questionnaires assessing mood, hangover symptom severity, and previous night's sleep. The effects of the MTF on mood and perceived workload were also assessed. Participants in the hangover condition reported significantly lower alertness and contentment coupled with a higher mental fatigue and anxiety. Multitasking ability was also significantly impaired in the hangover condition. Completion of the cognitive stressor increased reported levels of mental demand, effort, and frustration, and decreased perceived level of performance. MTF completion did not differentially affect mood. Lastly, participants rated their sleep as significantly worse during the night prior to the hangover compared with the control condition. These findings confirm the negative cognitive and mood effects of hangover on mood. They also demonstrate that hangover is associated with greater perceived effort during task performance.