• Energy Research

AbstractAdolescence is an important developmental period associated with increased risk for excessive alcohol use, but also high rates of recovery from alcohol use-related problems, suggesting potential resilience to long-term effects compared to adults. The aim of this systematic review is to evaluate the current evidence for a moderating role of age on the impact of chronic alcohol exposure on the brain and cognition. We searched Medline, PsycInfo, and Cochrane Library databases up to February 3, 2021. All human and animal studies that directly tested whether the relationship between chronic alcohol exposure and neurocognitive outcomes differs between adolescents and adults were included. Study characteristics and results of age-related analyses were extracted into reference tables and results were separately narratively synthesized for each cognitive and brain-related outcome. The evidence strength for age-related differences varies across outcomes. Human evidence is largely missing, but animal research provides limited but consistent evidence of heightened adolescent sensitivity to chronic alcohol’s effects on several outcomes, including conditioned aversion, dopaminergic transmission in reward-related regions, neurodegeneration, and neurogenesis. At the same time, there is limited evidence for adolescent resilience to chronic alcohol-induced impairments in the domain of cognitive flexibility, warranting future studies investigating the potential mechanisms underlying adolescent risk and resilience to the effects of alcohol. The available evidence from mostly animal studies indicates adolescents are both more vulnerable and potentially more resilient to chronic alcohol effects on specific brain and cognitive outcomes. More human research directly comparing adolescents and adults is needed despite the methodological constraints. Parallel translational animal models can aid in the causal interpretation of observed effects. To improve their translational value, future animal studies should aim to use voluntary self-administration paradigms and incorporate individual differences and environmental context to better model human drinking behavior.

BackgroundYoung adult heavy drinking is an important public health concern. Current interventions have efficacy but with only modest effects, and thus, novel interventions are needed. In prior studies, heavy drinkers, including young adults, have demonstrated stronger automatically triggered approach tendencies to alcohol‐related stimuli than lighter drinkers. Automatic action tendency retraining has been developed to correct this tendency and consequently reduce alcohol consumption. This study is the first to test multiple iterations of automatic action tendency retraining, followed by laboratory alcohol self‐administration.MethodsA total of 72 nontreatment‐seeking, heavy drinking young adults ages 21 to 25 were randomized to automatic action tendency retraining or a control condition (i.e., “sham training”). Of these, 69 (54% male) completed 4 iterations of retraining or the control condition over 5 days with an alcohol drinking session on Day 5. Self‐administration was conducted according to a human laboratory paradigm designed to model individual differences in impaired control (i.e., difficulty adhering to limits on alcohol consumption).ResultsAutomatic action tendency retraining was not associated with greater reduction in alcohol approach tendency or less alcohol self‐administration than the control condition. The laboratory paradigm was probably sufficiently sensitive to detect an effect of an experimental manipulation given the range of self‐administration behavior observed, both in terms of number of alcoholic and nonalcoholic drinks and measures of drinking topography.ConclusionsAutomatic action tendency retraining was ineffective among heavy drinking young adults without motivation to change their drinking. Details of the retraining procedure may have contributed to the lack of a significant effect. Despite null primary findings, the impaired control laboratory paradigm is a valid laboratory‐based measure of young adult alcohol consumption that provides the opportunity to observe drinking topography and self‐administration of nonalcoholic beverages (i.e., protective behavioral strategies directly related to alcohol use).

AbstractSocial attunement (SA)—the tendency to harmonize behavior with the social environment—has been proposed to drive the escalation of alcohol use in adolescence, while reducing use in adulthood. Little is known about how heightened social sensitivity in adolescence may interact with neural alcohol cue reactivity—a marker of alcohol use disorder—and its relationship to alcohol use severity over time. The aims of this study were to test whether (1) adolescents and adults differ in social alcohol cue reactivity in the nucleus accumbens, anterior cingulate cortex, and right medial prefrontal cortex (mPFC), and (2) age moderates the relationship between social alcohol cue reactivity and social attunement, measures of drinking at baseline, and changes in drinking over time. A sample of male adolescents (16–18 years) and adults (29–35 years) completed an fMRI social alcohol cue‐exposure task at baseline and an online follow‐up two to three years later. No main effects of age or drinking measures were observed in social alcohol cue reactivity. However, age significantly moderated associations of social alcohol cue reactivity in the mPFC and additional regions from exploratory whole‐brain analyses with SA, with a positive association in adolescents and negative association in adults. Significant age interactions emerged only for SA in predicting drinking over time. Adolescents with higher SA scores escalated drinking, while adults with higher SA scores reduced drinking. These findings warrant further research on SA as a risk and protective factor and suggest that social processes influence cue reactivity differentially in male adolescents and adults.

AbstractWhile imaging studies have demonstrated volumetric differences in subcortical structures associated with dependence on various abused substances, findings to date have not been wholly consistent. Moreover, most studies have not compared brain morphology across those dependent on different substances of abuse to identify substance‐specific and substance‐general dependence effects. By pooling large multinational datasets from 33 imaging sites, this study examined subcortical surface morphology in 1628 nondependent controls and 2277 individuals with dependence on alcohol, nicotine, cocaine, methamphetamine, and/or cannabis. Subcortical structures were defined by FreeSurfer segmentation and converted to a mesh surface to extract two vertex‐level metrics—the radial distance (RD) of the structure surface from a medial curve and the log of the Jacobian determinant (JD)—that, respectively, describe local thickness and surface area dilation/contraction. Mega‐analyses were performed on measures of RD and JD to test for the main effect of substance dependence, controlling for age, sex, intracranial volume, and imaging site. Widespread differences between dependent users and nondependent controls were found across subcortical structures, driven primarily by users dependent on alcohol. Alcohol dependence was associated with localized lower RD and JD across most structures, with the strongest effects in the hippocampus, thalamus, putamen, and amygdala. Meanwhile, nicotine use was associated with greater RD and JD relative to nonsmokers in multiple regions, with the strongest effects in the bilateral hippocampus and right nucleus accumbens. By demonstrating subcortical morphological differences unique to alcohol and nicotine use, rather than dependence across all substances, results suggest substance‐specific relationships with subcortical brain structures.

Introduction: Sleep continuity problems are widespread among college students and may be influenced by single-use and co-use of alcohol and cannabis. We examined the within-person associations of alcohol and cannabis use with subsequent sleep experiences in the everyday life of college students. Materials and Methods: A sample of 80 college students reported prior-night alcohol and cannabis use and sleep experiences for 14 consecutive days. Mixed-effects models examined the within-person relationships between alcohol and cannabis use (single- and co-use) and subsequent (1) sleep-onset latency, (2) total sleep time, (3) number of awakenings, and (4) early awakenings that night. Results: Compared to no-use evenings, alcohol and cannabis, used separately or together (co-use), were associated with shorter sleep-onset latency and longer total sleep time. Students reported more nightly awakenings after alcohol-only use compared to no-use and after co-use, and they reported fewer early awakenings after no-use and co-use. Conclusions: In line with previous experimental findings, we found that alcohol and cannabis use in the everyday life of college students were associated with sleep-inducing effects, and that alcohol use was associated with disturbed sleep continuity. The results suggest that cannabis may curb alcohol's detrimental effect on the number of awakenings and may reduce the incidence of early awakenings. Yet, due to lack of control for potentially important confounders (e.g., quantity of cannabis/alcohol consumed, withdrawal) the current results may be best seen as preliminary and further research is needed before causal inferences can be reached.