Carnegie Mellon University

Lilly McCleodLilly McCleod

Factors Predicting the Cessation of Cannabis when Developing Cannabinoid Hypermesis Syndrome

Advisor: Crista Crittenden
Major: Psychology


The increase and widespread use of cannabis over the past decade has enabled the recognition of cannabis for its pain relief and calming effects. Moreover, it has enabled the increase in the literature on cannabis dependence. The United States has seen one of the largest increases in cannabis use, with the prevalence rising by 34% from 2007 to 2015 among those above 12 years old. This led to an increase of 67% in daily cannabis users from 2007 to 2015, with rates of cannabis use disorder nearly doubling in the United States (Manning et al., 2018).

With the increase in cannabis users, there is an increased need for cannabis production, which has led producers to selectively breed the Cannabis Sativa plant. This results in producers increasing the average THC content as well as adding additives such as pesticides, chemicals or preservatives (Nicolson et al., 2012). The increased breadth of exposure to cannabis and stronger concentration of THC in cannabis has led to the emergence of Cannabinoid Hyperemesis Syndrome (CHS). CHS develops with prolonged daily use of cannabis, typically after 5-10 years of use. The symptoms include nausea and vomiting, which people attempt to control through compulsive hot baths and showers. The symptoms remain with continued use of cannabis. The only definite treatment is abstinence from cannabis (Sorensen et al., 2016).

Within the literature on CHS there is a gap in the exploration of the personal perspectives and insights of cannabis users and their relationship with cannabis, as well as how it may affect their ability to quit cannabis in the face of developing CHS. In order to provide the best support for people who develop CHS, as well as people who want to quit after prolonged use, it is necessary to adequately represent people's experiences with cannabis and the maintenance of its prolonged use. Such research would highlight what kinds of support they would need in order to successfully accomplish abstinence. I will specifically analyze which personal factors may predict who is going to quit cannabis usage when developing CHS. I will explore this through qualitative research, including online surveys, interviews and focus groups. I will attempt to gain access to online communities of cannabis users to be able to attain a more diverse sample population that is more representative of differing individuals' needs. I will analyze the data using various coding software, such as QDAminer and RQDA, and using R.


My background is shaped by a conjunction of people and cultures, with my mom being a white German woman and my dad being a black British/American man. This elaborate background formed the basis of my migratory family and my profound comprehension of all the differing cultures exhibited throughout diverse locations. This shaped me into the understanding, independent and well-rounded young woman I am today.

My journey started in London, England, where I lived the first three years of my life. Thereafter, we moved to Barcelona, Spain where we lived for seven years. My brother's talent at tennis led to our move to Germany. Finally, my eldest brother's desire to finish his high school career in the U.S. led to my family's final departure to Miami, Florida. All these moves to different countries shaped me as a very adaptable person and provided me with the flexibility and energy that has allowed me to travel through life and accustom myself effortlessly wherever needed.

I am a Psychology major and I met Dr. Crista Crittenden when I was taking her course, Social Factors and Well Being, in the fall of 2020. I really liked being part of this class and having the opportunity to study under Crittenden, because she provides you with the necessary information, resources and support to help you succeed in your endeavors. I liked her and the class so much that I wanted to continue studying under her and proceeded to take Research Methods in Social Psychology with her in spring 2021. Given that Crittenden was only a lecturer at the time and did not have a lab, I was unable to do research with her. Therefore, I started working in Vicki Helgeson's Gender, Health, and Relationships lab in spring 2021. Following this experience, I wanted to keep working with Helgeson over the summer and enlisted in SURA, where I led Helgeson's PhD student's research project. In addition to working with Helgeson over the summer, I worked in the Behavioral Health lab under Casey Creswell. During my time there, I worked on running participants through the experimental alcohol administration protocol for the Behavioral Alcohol Response (BAR) Study.