How bad could it be? Alcohol dampens stress responses to threat of uncertain intensity

Abstract

Stress response dampening is an important motive for alcohol use. However, stress reduction via alcohol (alcohol SRD) is observed inconsistently in the laboratory, and this has raised questions about the precise mechanisms and boundary conditions for these effects. Emerging evidence indicates that alcohol SRD may be observed selectively during uncertain but not certain threats. In a final sample of 89 participants, we measured stress response via potentiation of defensive startle reflex in response to threat of shock in blocks with certain (low and high) and uncertain shock intensity. Our alcohol-administration procedure produced blood alcohol concentrations (BACs) across a broad range (0.00%-0.12%) across participants. Increasing BACs were associated with linearly decreasing startle potentiation and self-reported anxiety. This SRD effect was greater during uncertain than certain threat. More broadly, these results suggest that distinct mechanisms are involved in response to threats of uncertain intensity and threats of certain intensity.

Keywords: drug and substance abuse; emotions; startle reflex; stress reactions.

Fig. 1

Startle potentiation as a function of mean blood alcohol concentration (BAC) and threat type. The translucent bands indicate confidence envelopes (±1 SE) around the point estimates (dark lines) of mean startle potentiation from the general linear model. The strip plot (triangles) along the x-axis shows the observed mean BACs for all participants. The numbers in the right margin are coefficients from the general linear model, showing the simple effect of BAC for each threat type (*p < .05; **p < .001).

Fig. 2

Component-plus-residual plots for the effect of blood alcohol concentration (BAC) on startle potentiation during certain and uncertain threat. Component-plus-residual plots are used to assess linearity of effects in general linear models (Fox, 2008). Startle potentiation scores in these plots were adjusted to control for all regressors in the models other than BAC.

Fig. 3

Self-reported anxiety (1 = not at all anxious; 5 = extremely anxious) as a function of mean blood alcohol concentration (BAC) and threat type. The translucent colored bands indicate confidence envelopes (±1 SE) for point estimates (dark lines) of self-reported anxiety from the general linear model. The strip plot (triangles) along the x-axis shows the observed mean BACs for all participants. The numbers in the right margin are coefficients from the general linear model, showing the simple effect of BAC for each threat type (*p < .050; **p < .001).