COVID Stay-at-Home Orders Worsened Mental Health, But Worsening Mental Health Reduced Cannabis Use
In a nationally representative study of 7,554 Americans, stay-at-home orders doubled the odds of moderate-to-severe depression, but worsening depression and anxiety was associated with less marijuana use, not more, contradicting the self-medication hypothesis.
Quick Facts
What This Study 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.
Key Numbers
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 They Did This
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.
Why This Research 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 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.
What This Study Doesn't 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
Questions This Raises
- ?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?
Trust & Context
- Key Stat:
- Worsening depression during COVID was linked to 78% lower odds of marijuana use, not higher
- Evidence Grade:
- Large nationally representative longitudinal panel with repeated measurements and mediation analysis; strong design but self-reported measures
- Study Age:
- Published 2025
- Original Title:
- Depression and anxiety mediate the relationship between COVID-19 stay-at-home orders and tobacco and marijuana use.
- Published In:
- PloS one, 20(12), e0337996 (2025)
- Authors:
- Carney-Knisely, Geoffrey(2), Pek, Jolynn, Ferketich, Amy K(2), Padamsee, Tasleem J, Gur, Tamar, Singh, Parvati
- Database ID:
- RTHC-06161
Evidence Hierarchy
Follows a group of people over time to track how outcomes develop.
What do these levels mean? →Frequently Asked Questions
Did people use more marijuana during COVID lockdowns?
Counterintuitively, this study found that people whose mental health worsened during stay-at-home orders actually used less marijuana, not more. Worsening depression was associated with 78% lower odds of marijuana use.
Does depression lead to more substance use?
Not in this study. The common assumption that worsening mental health drives self-medication with substances was contradicted: people with moderate-to-severe depression had 63% lower odds of marijuana use compared to those with normal-to-mild symptoms.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-06161APA
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
MLA
Carney-Knisely, Geoffrey, et al. "Depression and anxiety mediate the relationship between COVID-19 stay-at-home orders and tobacco and marijuana use.." PloS one, 2025. https://doi.org/10.1371/journal.pone.0337996
RethinkTHC
RethinkTHC Research Database. "Depression and anxiety mediate the relationship between COVI..." RTHC-06161. Retrieved from https://rethinkthc.com/research/carney-knisely-2025-depression-and-anxiety-mediate
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.