Alcohol dose effects on stress response to cued threat vary by threat intensity

Abstract

Rationale: Clarification of alcohol's effect on stress response during threat is critical to understand motivation for alcohol use and related alcohol-use disorders. Evaluation of stress response dampening (SRD) effects of alcohol has been limited by nonsystematic use of varied experimental methods and measures.

Objectives: This experiment parametrically varied alcohol dose and shock threat intensity among social drinkers to examine their effects on startle potentiation, a physiological measure of the affective component of the stress response.

Methods: Ninety-six participants were assigned to one of four beverage groups: placebo and target blood alcohol concentration (BAC) groups of 0.04%, 0.075%, and 0.11%. Participants viewed colored cues presented in shock and no-shock blocks. Distinct colored cues predicted imminent low, moderate, or high intensity electric shock administration. Startle potentiation during shock threat relative to no-shock cues indexed affective response.

Results: High threat increased startle potentiation relative to moderate/low intensity threat. Startle potentiation decreased as BAC increased. Threat intensity moderated this BAC effect with the strongest BAC effect observed during high threat. Analysis of individual difference moderators revealed reduced effect of BAC among heavier, more problematic drinkers.

Conclusions: Clear alcohol SRD effects were observed. These SRD effects were greatest at higher BACs and during more potent threat. Failure to account for these factors may partially explain inconsistent findings in past laboratory SRD research. Furthermore, they suggest greater reinforcement from alcohol at higher doses and among individuals with greater stress. Moderation of SRD effects by alcohol consumption and problems point to possible important risk factors.

Figures

Fig 1. Histogram of participants’ mean achieved blood alcohol concentration (BAC) by Beverage Group

BAC was averaged over measurements obtained immediately pre-task and post-task.

Fig. 2. Startle potentiation by BAC and threat intensity

Startle potentiation was calculated as startle magnitude during shock threat cues vs. no-shock cues. Dark lines display the relationship between BAC and startle potentiation separately for each level of threat intensity (low vs. moderate vs. high). Light grey lines represent +1 standard error bands for point estimates of mean startle potentiation at each threat intensity from the general linear model for this analysis. A rug plot of observed BACs for participants in the sample is included along the x-axis.

Fig. 3. Individual different moderators of BAC effect

Left panel: Startle potentiation by BAC for participants with low and high weekly alcohol consumption. Point estimates for low and high alcohol consumption were obtained at + 1 standard deviation relative to the sample mean consumption (i.e., 0.5 vs. 18.4 drinks/week). Light grey lines represent standard error bands for point estimates from the general linear model for this analysis. A rug plot of observed BACs for participants in the sample is included along the x-axis. Right panel: Startle potentiation by BAC for participants with low and high past year alcohol problems. Alcohol problems were measured with the Young Adult Alcohol Problems Screening Test (Hurlbut and Sher 1992). Point estimates for low and high alcohol problems were obtained at + 1 standard deviation relative to the sample mean problems (i.e., 1.7 vs. 8.2 past year problems). Light grey lines represent standard error bands for point estimates from the general linear model for this analysis. A rug plot of observed BACs for participants in the sample is included along the x-axis.