Among over 4 million VHA patients tracked from 2005-2022, cannabis legalization was associated with greater CUD prevalence increases in veterans with psychiatric disorders than in those without.
VA clinicians, cannabis policy researchers, mental health treatment planners, legislators
What the researchers found
CUD prevalence among veterans with any psychiatric disorder rose from ~3.3% in 2005 to ~5.7-6.4% by 2022, depending on state legalization status. Using staggered difference-in-difference analysis, both medical and recreational cannabis legalization were associated with significantly greater CUD increases among patients with psychiatric disorders (depression, PTSD, anxiety, bipolar, psychotic-spectrum) compared to those without. CUD prevalence remained below 1% in all years among patients without psychiatric disorders.
Why it matters
This is one of the largest and longest studies connecting cannabis legalization to CUD outcomes in a vulnerable population. The finding that psychiatric patients are disproportionately affected by legalization has direct implications for how states approach cannabis policy alongside mental health care.
The numbers in context
3.2-4.4 million VHA patients/year; 18 years of data; APD-positive CUD rose from ~3.3% to ~5.7-6.4%; APD-negative CUD stayed <1%; legalization effects significantly larger for psychiatric patients; effects consistent across depression, PTSD, anxiety, bipolar, psychotic disorders
How the study worked
Analysis of VHA electronic medical records (2005-2022) for patients aged 18-75 with primary care, ED, or mental health visits. Sample sizes ranged from 3.2 to 4.4 million per year. Staggered difference-in-difference models estimated effects of medical and recreational cannabis legalization on CUD prevalence, comparing patients with and without specific psychiatric disorders.
What this study cannot tell us
VHA patients are predominantly male and may not generalize. CUD diagnosis depends on provider recognition and coding, which may have changed over time. DiD estimates were modest, suggesting other factors (commercialization, attitudes) also drive CUD increases. Cannot distinguish between legalization increasing CUD vs increasing detection.
How to read the evidence
Strong: massive longitudinal dataset with rigorous causal inference methods (staggered DiD), though limited by administrative data characteristics.
When this study was published
2025 publication using 2005-2022 data
The bigger picture
Cannabis legalization is primarily discussed as a social justice and economic issue, but this study quantifies a specific health cost: more cannabis use disorders among the most psychiatrically vulnerable patients. This trade-off deserves explicit consideration in policy debates.
Questions still open
- Should cannabis legalization policies include earmarked funding for psychiatric CUD treatment?
- Is the increase in CUD diagnoses partly driven by increased screening rather than true prevalence?
Read the original research
Cannabis legalization and cannabis use disorder in United States Veterans Health Administration patients with and without psychiatric disorders, 2005-2022: a repeated cross-sectional study.
Lancet regional health. Americas, 48, 101155
Citation
Hasin, Deborah S; Malte, Carol; Wall, Melanie M; Alschuler, Daniel; Simpson, Tracy L; Olfson, Mark; Livne, Ofir; Mannes, Zachary L; Fink, David S; Keyes, Katherine M; Cerdá, Magdalena; Maynard, Charles C; Keyhani, Salomeh; Martins, Silvia S; Sherman, Scott; Saxon, Andrew J. (2025). Cannabis legalization and cannabis use disorder in United States Veterans Health Administration patients with and without psychiatric disorders, 2005-2022: a repeated cross-sectional study.. Lancet regional health. Americas, 48, 101155. https://doi.org/10.1016/j.lana.2025.101155