Dose-dependent effects of alcohol consumption on pressure pain threshold.

Introduction: Prior laboratory-based studies have identified significant analgesic effects of acute alcohol. Despite providing excellent experimental control, these studies are limited regarding the range of alcohol exposure that can be practically and ethically achieved. This study capitalized on the heterogeneity in breath alcohol concentration (BrAC) resulting from naturalistic alcohol use at a public event to improve understanding of alcohol analgesia. We hypothesized that BrAC would be significantly and positively associated with pain threshold.

Methods: Participants were attendees of the 2024 Minnesota State Fair reporting alcohol use within the last month (N = 149, 55 % women). Each completed a brief assessment of pressure pain threshold at the first dorsal interosseus muscle. BrAC was measured using a standard breathalyzer device. Hierarchical multiple regression analysis characterized BrAC as a predictor of pain threshold, controlling for covariates including clinical pain, age, sex, typical drinking, participant/experimenter gender matching, and expectancies of alcohol analgesia.

Results: 30.9 % of participants had non-zero BrACs, with an average of 0.038 g/dL. Average pain threshold was 3.58 kgf/cm. Higher BrAC predicted greater pain threshold in both the whole sample (b = 0.145, p = 0.001, η = 0.07) and those participants with non-zero BrACs (b = 0.184, p = 0.009, η = 0.18). Men had significant greater pain thresholds than women (p = 0.007, η = 0.052), but no other covariates reached significance. Addition of quadratic and cubic BrAC terms did not improve model fit.

Discussion: Results suggest a significant, dose-dependent association of alcohol use with increased pain threshold, independent of age, sex, number of reported pain conditions, participant/experimenter gender matching, or beliefs regarding alcohol analgesia. The acute analgesic effects of alcohol may scale linearly with amount consumed, at least within the BrAC range observed in the study.