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Addictions, Drug & Alcohol Institute > Cannabis Education & Research Program (CERP) > Cannabis Projects

Cannabis Projects

Current projects (as of July 2025)

A Matter of Equity: People Living with Psychosis are Disproportionately Affected by Cannabis Adverse Events

October 2024 – August 2025
Status: Manuscript prepared and submitted

Cannabis use has been shown to negatively impact the management and prognosis of psychotic disorders. Little is known about the broader health impacts of cannabis use in this population. This study compares cannabis-related negative health outcomes among individuals with a diagnosis of a psychotic disorder to those with other mental health (MH) diagnoses or no MH diagnosis.

Data came from International Cannabis Policy Study (2020-2023). Respondents were 4,144 Washington State individuals aged 16–65, who consumed cannabis in the last 12 months. Three groups were compared for cannabis use negative health events: (lifetime diagnoses of psychotic disorders, other MH and no MH diagnoses). Logistic regressions were used in the analysis.

People with psychotic disorders were more likely to report adverse events from their cannabis use and to pursue medical attention than consumers with other MH or no MH diagnoses (p<.001.) They had higher likelihood of nausea/vomiting (2.2 to 3.7 times as likely), heart or blood pressure problems (3.3 to 8.6), fainting (2.7 to 4.9), acute psychosis or hallucinations (5.4 to 6.2), flashbacks (4.3 to 11.5), Cannabis Hyperemesis Syndrome (3.1 to 7) and positive screening for high-risk cannabis use (3.4 to 6.9) than consumers with other MH or no MH diagnoses.

Individuals with psychotic disorder experience more adverse health events from cannabis, including events not associated with exacerbation of their disorders. These findings highlight the need to develop focused clinical interventions and awareness campaigns to address elevated risks of cannabis use among this vulnerable population.

Funded by the Washington State Legislature through ESSB 5187 (2023) and by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators

Cannabis Adverse Events in Clinical Practice: An Assessment of WA Clinicians’ Practices, Knowledge and Needs

October 2024 – August 2025
Status: Manuscript in development

Little is known about clinician knowledge, beliefs, and clinical practices in cases involving cannabis-related AEs. Understanding clinician beliefs and behaviors related cannabis adverse events can inform future clinician education and training. It can also map opportunities for implementing clinical interventions that can prevent cannabis AE recurrence and severity by encouraging patients to quitting/decreasing their cannabis consumption or to adopt safer use behaviors.  

Accordingly, this project conducted a needs assessment study exploring knowledge, beliefs, clinical practices, interest on intervening in cannabis AEs and personal and institutional barriers for addressing cannabis AEs among health care providers in Washington State. 

Funded by the Washington State Legislature through ESSB 5187 (2023) and by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators

Reporting THC Content in Cannabis Products in Legal Markets: An international Multidisciplinary Delphi Consensus Study 

Status: Data collection

In countries where cannabis products are legal, the THC content on licensed cannabis products is inconsistently reported (e.g., % percentage or concentration, milligrams). This project aim to establish guidelines on how to report the amount of Delta-9-Tetrahydrocannabinol (THC) consistently and accurately across all cannabis products. To achieve this goal, the project will utilize a Delphi methodology with a multidisciplinary and international expert to achieve consensus on how to report THC content for consumers (e.g., product labelling and packaging) across all cannabis products (e.g., medical/non-medical, administered via distinct modes).

Steering Committee members

Cannabis Adverse Events among Medicaid Recipients in WA State 

July 2024 – June 2025
Status: Data pull in process

With cannabis legalization in WA State has come an increase in cannabis use prevalence, daily use, and THC concentration of available products. These changes have been linked to corresponding health care utilization due to cannabis-related adverse outcomes in Colorado and Canada. These outcomes range from acute events such as panic attacks, cannabis-induced psychosis, vomiting and cardiac events to conditions that typically develop over time, such as cannabis hyperemesis syndrome and cannabis use disorder. Little is known about health care utilization due to cannabis-related adverse outcomes in WA State, the type of events seen most frequently, and how and if they are being recorded in medical records and claims.  

This project will use statewide Medicaid claims data to describe cannabis-related adverse outcomes among Medicaid patients in primary care, hospitals, and emergency departments across the state. Descriptive analyses will (aim 1) identify the prevalence of specific types of cannabis-related events, (aim 2) who is most affected (age, race/ethnicity, gender, county, and other diagnoses), and (aim 3) the healthcare settings most commonly responding to these events.

Funded by the Washington State Dedicated Cannabis Fund for research at the University of Washington. 

Investigators

Completed Projects

2025

2024

2023 and earlier