Evaluating the impact of psychotherapeutic advertising claims on cannabis purchasing - PROJECT SUMMARY In the U.S., legal cannabis is frequently advertised as an effective treatment for mental health problems such as anxiety and depression – particularly online. States that have legalized cannabis have not implemented regulations to address this type of advertising. This project aims to investigate the influence of psychotherapeutic advertising claims (PAC) and mental health warning labels (WL) on online cannabis purchasing behaviors among light-to-moderate cannabis users with symptoms of depression and/or anxiety. The specific aims are to determine if PAC increases cannabis purchasing intentions and if a mental health WL can mitigate this effect. A realistic online cannabis shopping experience will be simulated using the digital “Platform for Online Evaluation of Marijuana Marketing and Sales” (POEMMS). The study will employ a between-subjects experimental design by randomizing 2,000 participants to one of four online stores that vary in PAC and WL content: (1) a control claims (CC) only store, (2) a PAC store, (3) a WL store, and (4) a PAC and WL store. Participants will browse and select items as if making real purchases. Analyses will examine three primary outcomes to determine the influence of PAC and WL on purchase behaviors: (1) total milligrams of THC purchased, (2) average potency (%THC) of products, and (3) overall number of products purchased. The long- term objective is to inform evidence-based cannabis policy and regulatory strategies by understanding the impact of cannabis marketing on vulnerable populations. This research is relevant to public health by addressing the potential risks associated with misleading cannabis marketing, which may lead to increased use and exacerbation of mental health symptoms among individuals with depression and anxiety. The project leverages a multidisciplinary team with expertise in addiction, mental health, epidemiology, and digital health technology. The findings have the potential to inform the development of targeted interventions and policies to reduce harms associated with cannabis advertising, ultimately contributing to better health outcomes and more effective regulation.