Jarrod Ellingson, PhD
Assistant Professor, Psychiatry-Substance Dependence, University of Colorado School of Medicine

In the last 10 years, cannabis has become more accessible and more potent in tetrahydrocannabinol [THC] content. Prior studies have linked earlier cannabis use and greater THC potency to adverse mental health outcomes. However, these studies generally suffer from two important limitations. First, cannabis use has primarily been assessed in a pre-legalization environment, when THC potencies were lower. Second, most studies of adolescent cannabis use have not considered familial confounds, such as genetic or environmental factors. This study will recruit sibling pairs to examine the mental health effects of cannabis while controlling for important familial factors. Specifically, we will test whether participants with heavier cannabis use have worse mental health functioning, on average, compared to their sibling. Within this study design, we will also examine the short-term effects of adolescent cannabis use, such as whether school week functioning is affected by weekend cannabis use. Short-term effects are important because they can help to identify mechanisms of long-term effects. Thus, this study will help to understand the mental effects of cannabis in adolescents, while controlling for family background factors.