Effects of ethanol and tobacco on time judgment

Pharmacological Options for Smoking Cessation in Heavy-Drinking Smokers

There is a high prevalence of comorbid tobacco use and alcohol use disorder (AUD), affecting more than 6 million people in the US. Globally, tobacco and alcohol use rank fourth and fifth, respectively, for disability-adjusted life-years lost. Levels of alcohol use are higher in smokers than nonsmokers, and the prevalence of smoking is higher in heavy drinkers compared with nondrinkers. This relationship is driven by many different factors, including genetics, neurobiological mechanisms, conditioning processes, and psychosocial influences. Although this unique population tends to experience more negative health consequences, more severe AUD, and poorer response to treatment than those with either AUD or tobacco use disorder alone, there are currently no available treatment protocols tailored to this comorbid condition. In this review, we provide a comprehensive review of ongoing clinical research into smoking cessation options for heavy-drinking smokers (HDS) through an evaluation of the effect of promising novel pharmacotherapies as well as combination therapies, including varenicline, naltrexone, the combination of varenicline and naltrexone, and the combination of naltrexone and nicotine replacement therapy (NRT). These treatments are considered in light of the standard of care for smoking cessation, and seek to improve upon the available guidelines for this sizeable subgroup of smokers, namely those smokers who drink heavily.

Positive and negative effects of alcohol and nicotine and their interactions: a mechanistic review

Nicotine and alcohol are two of the most commonly abused legal substances. Heavy use of one drug can often lead to, or is predictive of, heavy use of the other drug in adolescents and adults. Heavy drinking and smoking alone are of significant health hazard. The combination of the two, however, can result in synergistic adverse effects particularly in incidences of various cancers (e.g., esophagus). Although detrimental consequences of smoking are well established, nicotine by itself might possess positive and even therapeutic potential. Similarly, alcohol at low or moderated doses may confer beneficial health effects. These opposing findings have generated considerable interest in how these drugs act. Here we will briefly review the negative impact of drinking-smoking co-morbidity followed by factors that appear to contribute to the high rate of co-use of alcohol and nicotine. Our main focus will be on what research is telling us about the central actions and interactions of these drugs, and what has been elucidated about the mechanisms of their positive and negative effects. We will conclude by making suggestions for future research in this area.

Comprehensive deficits in performance of an attentional task produced by co-administering alcohol and nicotine to rats

BACKGROUND

Nicotine can improve and alcohol can impair attentional performance in rats, but little is known about the effects of mixtures of the two drugs with respect to attention.

AIMS

The aims were to investigate the effects of alcohol and nicotine alone and when co-administered on performance of a five-choice serial reaction time task, and to examine the impact of task difficulty by varying durations of the limited hold (LH) for availability of the reinforcer.

METHODS

Male hooded rats were trained to respond (nose-poke) to a 0.5 s light stimulus presented randomly in one of five apertures to obtain food reinforcers. Three groups of rats trained with different LH values were used (n = 10).

RESULTS

The first experiment showed that training at different LH values had little effect on performance when the LH value during testing was held constant. Experiment 2 showed that alcohol (0.4-1.6 g/kg, i.p.) had no effect on the percentage of correct responses (accuracy) but it impaired all speed-related indices. In the third experiment, the effects of nicotine (0.1 and 0.2 mg/kg, s.c.) were determined alone and on the dose-response curve for alcohol (0.4-1.2 g/kg, i.p.). Nicotine alone produced small improvements in performance whereas co-administration of nicotine and alcohol produced large decrements at doses of alcohol that themselves only slightly impaired performance. These decrements included impairments of accuracy as well as of anticipatory responding, omission errors, response latencies and reinforcers earned. There were no marked or consistent interactions of drug effects with LH values.

CONCLUSIONS

Task performance was disrupted to a much greater extent by co-administration of alcohol and nicotine than by alcohol alone; therefore, it seems unlikely that an ability of nicotine to reverse the effects of alcohol can account for associations between the use of the two substances.

Evidence for a relationship between daily caffeine consumption and accuracy of time estimation

The present study examined the relationship between regular caffeine consumption and time estimation. Sixty participants (aged 18-57 years, mean 24 years) completed a 47 s time estimation exercise and questionnaires related to daily caffeine consumption and perceptions of time. We hypothesized that the effects of caffeine on time estimation would follow a U-shaped pattern such that individuals who reported moderate amounts of daily caffeine would be more accurate in their perceptions of time than would those who reported high amounts of caffeine intake or no daily caffeine consumption. Timing accuracy was computed by dividing participant-reported time by actual time (47 s). Timing accuracy followed a U-shaped curve such that those respondents who reported 'low' daily caffeine consumption (< or = 135 mg/day, n = 24) were the most accurate in their time estimates (mean= 44.2 s). Individuals who reported no caffeine (mean= 69.3 s; n= 7) or 'high' daily caffeine consumption (mean=56.2 s; >135 mg/day, n = 28) were less accurate in their time estimates [F(2, 56)= 3.34, p< 0.05]. Findings suggest that 'low' daily caffeine consumption may enhance time estimation accuracy above that of 'high' or no daily caffeine consumption.

Effects of alcohol on velocity perception: I. Stimulus velocity and change in performance over time

17 subjects who were required to estimate the time of arrival at a target of a moving light overestimated less after alcohol treatment than after placebo.

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.

Effects of tobacco, time on task, and stimulus speed on judgments of velocity and time

16 college students were required to predict the time of target arrival for a stimulus apparently moving horizontally to a point of occlusion and to reproduce the time interval the stimulus was present under smoking and no-smoking conditions. Tobacco resulted in underestimations of velocity and time judgments particularly in the early stage of the task and for the slowest stimulus speed.