Effects of Age and Acute Moderate Alcohol Administration on Electrophysiological Correlates of Working Memory Maintenance

WOMEN'S USE OF ALCOHOL: NEUROBIOBEHAVIORAL CONCOMITANTS AND CONSEQUENCES

In this narrative review, we draw from historical and contemporary literature to explore the impact of alcohol consumption on brain and behavior among women. We examine three domains: 1) the impact of alcohol use disorder (AUD) on neurobiobehavioral outcomes, 2) its impact on social cognition/emotion processing, and 3) alcohol's acute effects in older women. There is compelling evidence of alcohol-related compromise in neuropsychological function, neural activation, and brain structure. Investigations of social cognition and alcohol effects in older women represent emerging areas of study. Initial analyses suggest that women with AUD show significant deficits in emotion processing, a finding also observed in older women who have consumed a moderate dose of alcohol. Critically, despite the long-recognized need for programmatic interrogation of alcohol's effect in women, studies with sufficient numbers of women for meaningful analysis represent a small proportion of the literature, constraining interpretation and generalization.

Effects of Age and Acute Moderate Alcohol Consumption on Electrophysiological Indices of Attention

OBJECTIVE

Despite increased attention to risks and benefits associated with moderate drinking lifestyles among aging adults, relatively few empirical studies focus on acute alcohol effects in older drinkers. Using electroencephalographic indices of early attention modulation (P1 and N1) and later stimulus processing (P3), we investigated whether acute alcohol consumption at socially relevant doses differentially influences neurocognitive performance in older, relative to younger, moderate drinkers.

METHOD

Younger (25-35 years; n = 97) and older (55-70 years; n = 87) healthy drinkers were randomly assigned to receive one of three alcohol doses (placebo, .04 g/dl, or .065 g/dl target breath alcohol concentrations). Repeated-measures analysis of variance examined the effects of age, alcohol dose concentration, and their potential interaction on P1/P3 amplitudes and N1 latency during completion of a directed attend/ignore task.

RESULTS

Age-specific effects on P1 amplitudes varied by instruction set, with alcohol-associated decreases in amplitude among older drinkers in response to task-relevant stimuli and increases to irrelevant stimuli, F(2, 141) = 2.70, p = .07, ηp2 = .04. In contrast, N1 analyses demonstrated alcohol-related latency reductions among older, relative to younger, adults, F(2, 83) = 3.42, p = .04. Although no Age × Alcohol interactions were detected for P3, main effects indicated dose-dependent amplitude reductions for relevant stimuli, F(2, 144) = 5.73, p < .01, ηp2 = .08.

CONCLUSIONS

Our results underscore the impact of acute moderate alcohol consumption on attentional functioning, highlighting age-dependent sensitivity in electrophysiological indices of early attentional processing. Given the import of attentional functioning to quality of life and increases in drinking among a rapidly expanding aging population, these findings have broad public health relevance.

Clarifying the neurobehavioral sequelae of moderate drinking lifestyles and acute alcohol effects with aging

Epidemiological estimates indicate not only an increase in the proportion of older adults, but also an increase in those who continue moderate alcohol consumption. Substantial literatures have attempted to characterize health benefits/risks of moderate drinking lifestyles. Not uncommonly, reports address outcomes in a single outcome, such as cardiovascular function or cognitive decline, rather than providing a broader overview of systems. In this narrative review, retaining focus on neurobiological considerations, we summarize key findings regarding moderate drinking and three health domains, cardiovascular health, Type 2 diabetes (T2D), and cognition. Interestingly, few investigators have studied bouts of low/moderate doses of alcohol consumption, a pattern consistent with moderate drinking lifestyles. Here, we address both moderate drinking as a lifestyle and as an acute event. Review of health-related correlates illustrates continuing inconsistencies. Although substantive reductions in risk for cardiovascular and T2D events are reported, robust conclusions remain elusive. Similarly, whereas moderate drinking is often associated with enhanced cognition and lower dementia risk, few benefits are noted in rates of decline or alterations in brain structure. The effect of sex/gender varies across health domains and by consumption levels. For example, women appear to differentially benefit from alcohol use in terms of T2D, but experience greater risk when considering aspects of cardiovascular function. Finally, we observe that socially relevant alcohol doses do not consistently impair performance in older adults. Rather, older drinkers demonstrate divergent, but not necessarily detrimental, patterns in neural activation and some behavioral measures relative to younger drinkers. Taken together, the epidemiological and laboratory studies reinforce the need for greater attention to key individual differences and for the conduct of systematic studies sensitive to age-related shifts in neurobiological systems.

Working Memory Performance Following Acute Alcohol: Replication and Extension of Dose by Age Interactions

OBJECTIVE

Despite the substantial number of older adult drinkers, few studies have examined acute alcohol effects in aging samples. We have explored these interactions across a variety of neurobehavioral domains and modalities and have consistently observed age-contingent vulnerabilities to alcohol-associated decrements in neurobehavioral functions. However, these studies have not been sufficiently powered to address sex differences, and, thus far, no attempt has been made to replicate results. The current study addresses these gaps.

METHOD

The study used a double-blind, placebo-controlled, factorial design with two age groups (older, 55-70 years; younger, 25-35 years) and three doses (target breath alcohol concentrations: .00, .04, and .065 g/dl). Replication analyses used an independent sample (n = 90) to replicate age-contingent alcohol effects reported by Boissoneault (n = 90). Samples were combined (N = 180; 91 women) to enable sex analyses. The dependent measure was performance efficiency in a visual working memory task.

RESULTS

A complex interaction between sex, age, and dose, F(2, 178) = 4.15, p = .02, appeared driven by age-contingent divergence in working memory performance, which was most pronounced between women at the .065 dose, t(28) = 4.61, p < .01, d = 1.68. Replication analyses revealed a pattern of age differences consistent with previous results, although the previously reported age by alcohol interaction failed to reach statistical significance.

CONCLUSIONS

Results provide further support for the hypothesis that neurobehavioral effects of acute alcohol are age dependent and offer evidence that this interaction may be moderated by sex. Extensions of this work are needed to identify underlying processes and ascertain the functional impact of these effects on the health and well-being of aging adult drinkers.

Effects of acute alcohol and driving complexity in older and younger adults

RATIONALE

Our previous work demonstrated differential neurobehavioral effects of low-dose alcohol consumption on older and younger adults in a driving simulator. However, the ability to enhance or suppress a response in such context has yet to be examined.

OBJECTIVES

The current study contrasted older and younger drivers' responses to specific stimuli (i.e., relevant, irrelevant) in scenarios of differing complexity following low-dose acute alcohol administration.

METHODS

Healthy older (55-70) and younger (25-35) adults completed two driving scenarios (i.e., country and metropolis) both before and after consuming beverages targeted to reach peak BrACs of 0.00, 0.04, or 0.065%. Throughout the simulation, participants encountered relevant stimuli (e.g., pedestrians walking into the street) and irrelevant stimuli (e.g., pedestrians walking parallel). Peak deceleration, range of steering, and distance until brake application were assessed within a 450-ft window preceding each stimulus.

RESULTS

Following low-dose alcohol consumption, older adults shifted from a strategy using both deceleration and steering to relying solely on deceleration in responding to relevant stimuli in the country. Older adults under both low and moderate alcohol conditions displayed an inability to withhold responses to irrelevant stimuli in the metropolis.

CONCLUSION

These findings are consistent with our prior work showing differential effects of low-dose alcohol on older, relative to younger, adults. The interactive effects of age and alcohol, however, depend on stimulus type and environmental complexity. Continued investigation of neurobehavioral mechanisms in ecologically valid paradigms is necessary for understanding the implications of the combined impairing effects of alcohol and older age.

Effects of Age and Acute Moderate Alcohol Administration on Neurophysiology During Simulated Driving

BACKGROUND

Driver age and blood alcohol concentration are both important factors in predicting driving risk; however, little is known regarding the joint import of these factors on neural activity following socially relevant alcohol doses. We examined age and alcohol effects on brain oscillations during simulated driving, focusing on 2 region-specific frequency bands implicated in task performance and attention: parietal alpha power (PAP; 8 to 12 Hz) and frontal theta power (FTP; 4 to 7 Hz).

METHODS

Participants included 80 younger (aged 25 to 35 years) and 40 older (aged 55 to 70 years) community-dwelling, moderate drinkers. Participants consumed placebo, low, or moderate doses of alcohol designed to achieve target peak breath alcohol concentrations of 0, 0.04, or 0.065 g/dl, respectively. Electrophysiological measures were recorded during engagement in a simulated driving task involving 4 scenarios of varied environmental complexity.

RESULTS

A main effect of age was detected in FTP, but neither an alcohol effect nor interactions were observed. For PAP, an age-by-alcohol interaction was detected. Relative to placebo controls, older and younger participants receiving low-dose (0.04 g/dl) alcohol evinced divergent PAP alterations, with a pattern of higher power among older participants and lower power among younger participants. This interaction was noted across the varied environmental contexts.

CONCLUSIONS

These findings are consistent with the hypothesis that compared with younger individuals, older drivers may be differentially susceptible to alcohol effects. While these age-by-alcohol interactions in neural activity are provocative, further investigation exploring the mechanisms and behavioral correlates of these effects will be crucial in determining their behavioral impact.