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

Stress response dampening (SRD) is an important motive for alcohol use. However, alcohol SRD is observed inconsistently in and out of the laboratory. This has raised questions about precise mechanisms and boundary conditions required for stress reduction from alcohol. Emerging evidence indicates that alcohol SRD may be observed selectively during uncertain but not certain threats. We measured stress response via potentiation of participants’ defensive startle reflex to threat of shock in blocks of certain (low and high) intensity and uncertain intensity shock. We manipulated 92 participants’ blood alcohol concentrations (BACs) across a broad range (0.00%-0.12%). Increasing BACs were associated with linearly decreasing startle potentiation and self-reported anxiety. This alcohol SRD effect was greater during uncertain than certain threat. Furthermore, we identified binge drinking as a moderator of alcohol SRD. More broadly, these results suggest that distinct mechanisms are involved in response to uncertain vs. certain intensity threats.