Does drinking cause depression, or does depression cause drinking? The arrow is contested

Alcohol and low mood travel together, and everyone has a theory about why. One camp says drinking causes depression and anxiety — the next-day "hangxiety," the depressant effect on the brain. The other says people drink to self-medicate feelings they already have. Both stories are intuitive, and recent evidence suggests both are shakier than their confident tellings imply. The direction of the arrow between drinking and mood is genuinely contested.

What genetic causal analysis suggests

One way to probe direction is Mendelian randomisation, which uses genetic variants as natural experiments to test whether one trait causally influences another rather than merely correlating. A 2026 study in Psychological Medicine applied this to depression, smoking and alcohol use, and stratified by sex — an important move, because the relationships differed markedly between men and women [s1].

The findings cut against the simplest self-medication story in one direction and support it in the other. Genetic liability to major depressive disorder increased the risk of problematic alcohol use in women [s1]. But no substance-use trait — including drinking — showed evidence of a causal effect on depression in either sex [s1]. In this analysis, in other words, depression appeared to drive problematic drinking in women, while drinking did not appear to cause depression [s1].

There were further twists. In men, genetic liability to depression was associated with reduced drinking frequency, not increased [s1]. And adjusting for socioeconomic status changed some associations, which is a reminder that the social conditions surrounding both depression and drinking are part of the picture, not noise to be removed [s1].

What within-person tracking adds

Genetic analysis works at the population level. A different study looked inside individuals over time, testing a leading theory — Koob's allostatic model — that drinking and negative emotional states feed each other in a spiral [s2]. Researchers tracked two samples of undergraduates, one of 3,138 and one of 417, across their college years, separating differences between people from changes within the same person over time [s2].

The results were more deflationary than the spiral model predicts. Between people, there was moderate-to-high overlap between alcohol withdrawal and negative affect, but only little-to-weak overlap between alcohol consumption itself and negative affect [s2]. Within individuals, there was no strong evidence of the back-and-forth prospective links the model expects between consumption and negative affect [s2]. What did show some coupling over time was withdrawal and negative affect, becoming more linked as drinking became heavier and more chronic [s2].

That distinction — between drinking and withdrawing — matters. It suggests the tight emotional coupling people describe may belong more to the withdrawal end of heavier, more established drinking than to ordinary consumption [s2].

Reconciling the two

The studies are not measuring the same thing, but they point in a compatible direction. The genetic work suggests depression can lead to problematic drinking more clearly than drinking leads to depression, at least in women [s1]. The within-person work suggests that for most drinkers, everyday consumption and mood are only weakly linked, with the stronger emotional coupling emerging around withdrawal in heavier, chronic use [s2].

Neither supports a simple, universal "alcohol makes you depressed" claim, and neither fully supports a blanket "people just drink to cope" claim [s1][s2]. The reality is conditional — on sex, on how heavy and established the drinking is, and on social circumstances.

The limits

These are two studies with real constraints. Mendelian randomisation rests on genetic assumptions that can be violated, and this analysis used data largely of European ancestry, so it may not generalise [s1]. The within-person study followed college students, a narrow and relatively young group whose drinking patterns differ from the wider population [s2]. Both examine associations and modelled causal structure rather than delivering a definitive verdict [s1][s2].

What they establish is that the popular certainties in both directions outrun the evidence, and that the honest answer depends on who is drinking and how much [s1][s2]. This article describes what the studies found. It is not medical advice, and anyone struggling with mood or drinking should speak with a clinician.