COVID Stay-at-Home Orders Worsened Mental Health, But Worsening Mental Health Reduced Cannabis Use

What the researchers found

People under stay-at-home orders had 2.18 times the odds of moderate-to-severe depression. However, those with moderate-to-severe depression had 63% lower odds of marijuana use (OR 0.37). Within-person worsening of mental health was associated with 78% lower odds of marijuana use (OR 0.22). Depression and anxiety appeared to mediate the pathway from stay-at-home orders to reduced marijuana use.

Why it matters

The dominant narrative during COVID was that people were self-medicating with substances. This study challenges that assumption: worsening mental health during lockdowns actually predicted less marijuana and cigarette use, not more, suggesting the self-medication model may be oversimplified.

The numbers in context

7,554 participants; 43,582 observations; SAH orders: OR 2.18 for moderate-severe depression (CI: 1.27-3.73); depression/anxiety: OR 0.37 for marijuana use (CI: 0.17-0.84); within-person mental health worsening: OR 0.22 for marijuana use (CI: 0.12-0.40); similar pattern for cigarettes (OR 0.29 for depression, OR 0.26 within-person)

How the study worked

Seven waves of the nationally representative Understanding America Study, a longitudinal web-based panel (N=7,554; 43,582 observations). Biweekly measurements of stay-at-home order status, PHQ-4 depression/anxiety scores, and past 7-day marijuana and cigarette use. Generalized estimating equations tested mediation models.

What this study cannot tell us

Self-reported substance use and mental health, biweekly measurements may miss within-period variation, cannot determine if reduced use was due to access limitations during lockdowns rather than mental state, seven waves cover limited pandemic period, cannot rule out underreporting

How to read the evidence

Large nationally representative longitudinal panel with repeated measurements and mediation analysis; strong design but self-reported measures

When this study was published

Published 2025

The bigger picture

The finding that worsening depression reduced rather than increased marijuana use challenges both the self-medication hypothesis and public health messaging about substance use during crises. People who become more depressed may withdraw from all activities, including substance use.

Questions still open

• Did reduced marijuana use during worsening depression reflect withdrawal from all activities (anhedonia) rather than a deliberate choice? Did access to marijuana decrease during lockdowns independently of mental health? Would longer follow-up reveal different patterns as the pandemic progressed?

Common questions

Read the original research

Depression and anxiety mediate the relationship between COVID-19 stay-at-home orders and tobacco and marijuana use.

PloS one, 20(12), e0337996

Citation

Carney-Knisely, Geoffrey; Pek, Jolynn; Ferketich, Amy K; Padamsee, Tasleem J; Gur, Tamar; Singh, Parvati. (2025). Depression and anxiety mediate the relationship between COVID-19 stay-at-home orders and tobacco and marijuana use.. PloS one, 20(12), e0337996. https://doi.org/10.1371/journal.pone.0337996

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