Using Placebo Beverages in Group Alcohol Studies

The impact of alcohol consumption on implicit racial bias

OBJECTIVE

Researchers and theorists studying intergroup relations have been interested in the impact of alcohol on interracial responding. Theories predict that alcohol will exacerbate expressions of racial bias by increasing reliance on stereotypes and/or by decreasing controlled processing and self-monitoring. Prior studies testing these theories have often examined alcohol's effects on implicit (i.e., indirect) measures of racial bias with inconsistent results. However, previous research in this area has suffered from several methodological limitations, including small sample sizes and doses of alcohol that may have been too low to induce substantial intoxication.

METHOD

Here, in more than triple the number of alcohol participants than the largest prior study, we tested whether an intoxicating dose of alcohol (target breath alcohol concentration of .08%) exacerbated implicit racial bias. Young adults who identified as races other than Black or African American (N = 207) were randomly assigned to consume an alcoholic or placebo beverage and completed the race-based Implicit Association Test (race IAT) testing implicit preference for White (vs. Black) individuals [or, conversely, bias against Black (vs. White) individuals].

RESULTS

All participants demonstrated an implicit racial bias (i.e., linking traditionally Black names with negative/unpleasant words), with no difference in this implicit racial bias across beverage conditions. Specifically, there were no differences between alcohol participants' race IAT D scores (M = 0.55, SD = 0.39), and placebo participants' race IAT D scores (M = 0.59, SD = 0.35), b = 0.05, 95%CI [-0.07, 0.18], p = .422.

CONCLUSIONS

These findings challenge theories and prior studies suggesting that alcohol increases implicit racial bias. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Peripheral blood transcriptomic profiling of molecular mechanisms commonly regulated by binge drinking and placebo effects

Molecular responses to alcohol consumption are dynamic, context-dependent, and arise from a complex interplay of biological and external factors. While many have studied genetic risk associated with drinking patterns, comprehensive studies identifying dynamic responses to pharmacologic and psychological/placebo effects underlying binge drinking are lacking. We investigated transcriptome-wide response to binge, medium, and placebo alcohol consumption by 17 healthy heavy social drinkers enrolled in a controlled, in-house, longitudinal study of up to 12 days. Using RNA-seq, we identified 251 and 13 differentially expressed genes (DEGs) in response to binge drinking and placebo, respectively. Eleven protein-coding DEGs had very large effect sizes in response to binge drinking (Cohen's d > 1). Furthermore, binge dose significantly impacted the Cytokine-cytokine receptor interaction pathway (KEGG: hsa04060) across all experimental sequences. Placebo also impacted hsa04060, but only when administered following regular alcohol drinking sessions. Similarly, medium-dose and placebo commonly impacted KEGG pathways of Systemic lupus erythematosus, Neutrophil extracellular trap formation, and Alcoholism based on the sequence of drinking sessions. These findings together indicate the "dose-extending effects" of placebo at a molecular level. Furthermore, besides supporting alcohol dose-specific molecular changes, results suggest that the placebo effects may induce molecular responses within the same pathways regulated by alcohol.

Peripheral blood transcriptomic profiling indicates molecular mechanisms commonly regulated by binge-drinking and placebo-effects

Molecular changes associated with alcohol consumption arise from complex interactions between pharmacological effects of alcohol, psychological/placebo context surrounding drinking, and other environmental and biological factors. The goal of this study was to tease apart molecular mechanisms regulated by pharmacological effects of alcohol - particularly at binge-drinking, from underlying placebo effects. Transcriptome-wide RNA-seq analyses were performed on peripheral blood samples collected from healthy heavy social drinkers (N=16) enrolled in a 12-day randomized, double-blind, cross-over human laboratory trial testing three alcohol doses: Placebo, moderate (0.05g/kg (men), 0.04g/kg (women)), and binge (1g/kg (men), 0.9g/kg (women)), administered in three 4-day experiments, separated by minimum of 7-day washout periods. Effects of beverage doses on the normalized gene expression counts were analyzed within each experiment compared to its own baseline using paired-t-tests. Differential expression of genes (DEGs) across experimental sequences in which each beverage dose was administered, as well as responsiveness to regular alcohol compared to placebo (i.e., pharmacological effects), were analyzed using generalized linear mixed-effects models. The 10% False discovery rate-adjusted DEGs varied across experimental sequences in response to all three beverage doses. We identified and validated 22 protein coding DEGs potentially responsive to pharmacological effects of binge and medium doses, of which 11 were selectively responsive to binge dose. Binge-dose significantly impacted the Cytokine-cytokine receptor interaction pathway (KEGG: hsa04060) across all experimental-sequences that it was administered in, and during dose-extending placebo. Medium dose and placebo impacted pathways hsa05322, hsa04613, and hsa05034, in the first two and last experimental sequences, respectively. In summary, our findings add novel, and confirm previously reported data supporting dose-dependent effects of alcohol on molecular mechanisms and suggest that the placebo effects may induce molecular responses within the same pathways regulated by alcohol. Innovative study designs are required to validate molecular correlates of placebo effects underlying drinking.

The effect of alcohol on mood among males drinking with a platonic friend

BACKGROUND

Despite the social nature of most drinking experiences, prior work has largely failed to incorporate social context into the study of alcohol's effects on emotion. The present study provides an initial test of the effect of alcohol on mood among platonic friends drinking together in a non-stress setting. We hypothesized that subjects would report more positive postdrink mood after consuming alcohol than after consuming a nonalcoholic control beverage.

METHODS

Dyads of platonic male friends (n = 36; 55.55% White, 38.88% Asian, 5.55% Black) attended two laboratory-based experimental sessions, wherein their drink conditions (alcohol vs. no alcohol control) were randomized by dyad and counter-balanced across sessions. They reported their mood before and after consuming their beverages together, using the Positive and Negative Affect Schedule and an 8-item mood measure.

RESULTS

As hypothesized, alcohol enhanced positive mood ( β  = 0.26, p < 0.01). Although in the expected direction, the effect of alcohol on negative mood was not significant ( β  = -0.12, p = 0.17). Post hoc analyses revealed that alcohol yielded greater increases in both stimulation ( β = 0.26 , p = 0.00) and sedation ( β = 0.40 , p = 0.00) as compared to the control condition.

CONCLUSION

This study highlights the positive mood-enhancing and broader subjective effects of alcohol when drinking with a platonic friend and encourages further consideration of friendship contexts in the examination of alcohol's effects when developing models of the etiology of alcohol use disorder.