Prevalence of anxiety and depression symptoms under population-level alcohol reduction to low-risk drinking: A parametric g-computation analysis in a U.S. nationwide cohort

Background: Alcohol consumption is a modifiable risk factor linked to anxiety and depression, yet the population-level impact of reducing alcohol use on the prevalence of anxiety and depression symptoms remains unclear. Prior studies are limited by methodological challenges including health-related selection into abstinence, time-varying confounding and reverse causation. Methods: We used data from 2,813 participants without documented underlying health conditions in a U.S. national longitudinal cohort (September 2021-December 2023) and applied the parametric g-formula within a target trial emulation framework to estimate the effect of a hypothetical intervention reducing alcohol consumption to low-risk levels on the prevalence of moderate-to-severe anxiety (GAD-7 [≥]10) and depression (PHQ-8 [≥]10) symptoms. The intervention set moderate- and high-risk drinking to low-risk at each follow-up, while leaving abstinent and low-risk drinking unchanged. Models adjusted for time-varying and baseline covariates, with uncertainty estimated using bootstrap resampling. Results: Under the natural course, the estimated prevalence of moderate-to-severe depressive symptoms was 12.67% (95% CI: 12.17, 13.23), compared to 12.77% (95% CI: 12.26, 13.29) under the intervention (risk difference: 0.10 percentage points; 95% CI: -0.22, 0.50). For anxiety symptoms, prevalence was 10.40% (95% CI: 8.89, 11.89) under the natural course and 10.25% (95% CI: 8.76, 11.98) under the intervention (risk difference: -0.15 percentage points; 95% CI: -0.68, 0.35). Conclusions: Under a hypothetical population-wide intervention reducing alcohol consumption to low-risk levels, differences in the prevalence of moderate or severe anxiety and depression symptoms were near null. These findings suggest that reducing alcohol use alone may be insufficient to meaningfully shift the population-wide burden of common mental health disorders.