Moderate Alcohol Consumption and Depression: A Marginal Structural Model Approach Promoting Causal Inference

Abstract

Objective: Moderate alcohol consumption is associated with decreased risk for depression, but it remains unclear whether this is a causal relationship or merely a methodological artefact. To compare the effects of consistent abstinence, occasional, moderate, and above-guidelines alcohol consumption throughout early-to-middle adulthood on depression at age 50, the authors conducted a secondary analysis of the National Longitudinal Survey of Youth 1979 cohort and employed a marginal structural model (MSM) approach. Methods: Baseline was set at 1994, when individuals were aged 29-37. The MSM incorporated measurements of alcohol consumption at 1994, 2002, and 2006, baseline and time-varying covariates, and repeated Centre for Epidemiological Studies-Depression Scale short form (CES-D-SF) measurements. 5,667 eligible participants provided valid data at baseline, with 3,593 of these providing valid outcome data. The authors used all observed data to predict CES-D-SF means and rates of probable depression for hypothetical trajectories of consistent alcohol consumption. Results: Results resembled J-shaped relationships. Specifically, both consistent occasional and consistent moderate drinkers were predicted to have reduced CES-D-SF scores and probable depression at age 50 compared to consistent abstainers (CES-D-SF scores: b=-0.84, CI= -1.47, -.11; probable depression: OR=0.58, CI=0.36, 0.88 for consistent occasional drinkers vs abstainers; CES-D-SF scores: b=-1.08, CI=-1.88, -.20; probable depression: OR=0.59, CI=0.26, 1.13for consistent moderate drinkers vs consistent abstainers). Consistent above-guidelines drinkers were predicted to have slightly increased risk compared to consistent abstainers, but this was not significant (b=0.34, CI=-0.62, 1.25; OR=1.06, CI =0.66, 1.72). In sex-stratified analyses, results were similar for females and males. Conclusions: The present study contributes preliminary evidence that associations between moderate alcohol consumption and reduced risk for depression may be genuine causal effects. Further research using diverse methodologies that promote causal inference is required.

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“…A recent study conducted a secondary analysis of the National Longitudinal Survey of Youth 1979 cohort and employed a marginal structural model (MSM) approach to investigate the association between alcohol consumption and depression. It found that both consistent occasional and consistent moderate drinkers were predicted to have reduced depressive scores and lower possible depression at age 50 compared to non-drinkers ( 55 ). Another study examined the association between the Mediterranean diet and depressive symptoms and found that moderate drinkers, compared to non-drinkers, were associated with lower depression and anxiety severity and lower odds of being currently depressed ( 56 ).…”

Association between drinking behaviors, sleep duration, and depressive symptoms

“…This is consistent with the findings of a previous study, which reported that abstaining from alcohol increases the likelihood of developing depression compared to light drinking 9 . Moreover, a recent longitudinal study examining the association between moderate alcohol consumption and depression showed that individuals who consistently consumed alcohol in moderate quantities, occasionally or regularly, were projected to have lower depressive symptoms and lower rates of probable depression upon attaining 50 years of age than those who consistently abstained from alcohol 14 . This suggests that our findings were consistent with those of previous studies that explored the relationship between alcohol consumption and depressive symptoms.…”

Is low‐level alcohol consumption really health‐protective? A critical review of approaches to promote causal inference and recent applications

“…When it comes to mental health outcomes, two studies have used MSMs to evaluate the relationship between alcohol and depression (Gémes et al., 2019; Visontay et al., 2023). Both studies—one in a Swedish and the other in a US population—support a J‐shaped relationship.…”

“…Ethanol's anti‐inflammatory action is a suggested mediator, but this is unsubstantiated. Additionally, for the apparent benefits conferred by low‐to‐moderate drinking against several conditions like dementia and depression, competing explanations promote either alcohol's benefits for social support/and interaction as a mediator, or else invoke direct biological effects (Visontay et al., 2023). For these conditions, the relative contributions of the two pathways remains largely unclear.…”