Interviewee: Dr. Justin Matheson, | Authors/Editors: Romina Garcia de leon, Janielle Richards (Blog Co-coordinators)
Published: September 6th, 2024
Can you briefly explain your research?
My research focuses on understanding how sex and gender shape substance use health, which encompasses the continuum from initial drug use experiences to substance use disorders. Specifically, in my current research, I am concentrating on two main areas. The first is examining differences in acute responses to cannabis using a human behavioral pharmacology paradigm. In this paradigm, participants smoke cannabis in the lab, and we observe categorical differences in their responses, such as how high they feel and their cognitive and sometimes driving performance. The second focus is on how gender influences trajectories and experiences in cannabis use disorder treatment, including the type and severity of symptoms experienced by individuals undergoing treatment to reduce or stop cannabis use. The aim is to better understand these trajectories, particularly in cisgender women and gender minorities, and to improve prevention and treatment strategies for substance use disorders, especially cannabis use disorders.
How did you get into this research?
I kind of stumbled into this field when, as a PhD student, my supervisor suggested that we explore differences in our initial cannabis lab study for a conference presentation. As I reviewed the literature, I became increasingly aware of how much harm in science has been caused by andronormativity, the focus on men and male bodies. Substance use has often been framed as a "men’s issue," and addiction in women is less understood, with limited research on addiction in gender minorities. As a gender-fluid person, I felt it was important to work towards gendered health equity in the addiction field within a restorative social justice framework, addressing gaps in understanding how substance use affects cisgender women and gender minorities.
How do you define sex and gender in your work?
Initially, my approach was to use a classic categorical difference model—males versus females. However, I am now shifting towards exploring the underlying factors driving these categorical differences. For example, I am interested in the relationship between gonadal hormone levels and acute responses to drugs, and how these relationships vary with the menstrual cycle or menopause. There is a significant lack of empirical evidence on how menopause might impact addiction risk. While my research is still grounded in binary categories, I aim to move beyond this binary to examine associated factors that affect all bodies differently based on gender. I think of gender as a way of making meaning of bodies and how societal understandings of gender influence how individuals are treated. Historically, substance use has been more stigmatized for women, contributing to underreporting and less focus in research. Women with cannabis use disorders often face more interpersonal conflicts, while men may experience more neurobiological or pharmacological harm. My research seeks to understand how gender and biology interact and how these interactions influence substance use and addiction.
Are there any findings you could share with us?
In our human laboratory work, we’ve encountered challenges. For example, in my initial PhD research, female participants smoked less cannabis than males and had lower THC levels in their blood than expected. Despite reporting similar subjective and cognitive effects as males, the difference in blood THC levels was significant. However, subsequent attempts to replicate this finding have been inconclusive. We are exploring how contextual factors (e.g., mood, expectations, prior cannabis use history) might moderate the relationship between THC exposure and intoxication states. We are also investigating the impact of menstrual cycle phase, estrogens, and androgens on cannabis use. In our gender-related research, which is primarily qualitative, we’ve identified notable gender narratives. For instance, men often seek treatment after struggling to cut back on cannabis, while women frequently cite external pressures and shame related to their cannabis use. These preliminary findings suggest a need for further exploration of how gender influences treatment-seeking behaviors and barriers to accessing care.
Where do you hope to see this work in 10 years?
In the next decade, I hope to secure more funding for research on specific factors related to substance use. There is a significant gap in understanding how menstrual cycle phases impact cannabis use, with only one published study in this area. I aim to fill this gap and explore neuroendocrinological approaches, including hormone modeling and genetic factors. Additionally, I hope to integrate gender more systematically into laboratory studies, moving beyond qualitative research to develop quantitative measures of gender. For example, understanding how individuals who identify as more feminine may experience cannabis intoxication differently could be crucial. Ultimately, I aim to merge research on gender and cannabis use disorder with studies on individual differences in drug responses, to improve prevention and treatment strategies for cannabis use disorders and other substance use disorders.
Where can you learn more about Dr. Justin Matheson’s work?
Website: https://www.justinrmatheson.com/
Twitter/X: https://x.com/justinrmatheson