Jacqueline Aloumanis
University of Florida
Co-Authors: Amanda Elton, University of Florida
Background: Cannabis and other substance misuse is common among individuals with symptoms of attention-deficit hyperactivity disorder (ADHD), particularly young adults and college students. Despite the growing perception that cannabis can be used as a therapeutic for ADHD, cannabis use among individuals with ADHD symptoms can also lead to cannabis use disorder and potential exacerbation of ADHD symptoms. Neurocognitive predictors of the risk for cannabis misuse among young adults with ADHD symptoms remain poorly understood.
Objective(s): Our analysis prospectively explored the neural predictors of the relationship between ADHD symptomology and cannabis use frequency. We hypothesized that ADHD symptoms would predict increased cannabis use, mediated by neural correlates of ADHD symptoms during performance of an inhibitory control task.
Methods: Data were collected from 144 first-year college students (ages 18-19) enrolled in a longitudinal neuroimaging and alcohol use investigation. Subjects at risk for alcohol use disorder were oversampled, but alcohol and other substance use disorders were excluded at baseline. Baseline assessments included an fMRI stop-signal task and the Conners Adult ADHD Rating Scales (CAARS). Cannabis use was assessed at baseline and for three yearly follow-up timepoints, through a self-report of days used in the previous year. Neural correlates of ADHD symptoms (CAARS DSM-IV Symptom subscales) were identified using Pearson correlations with the successful-stop-versus-go contrast from the stop-signal task. Sex interactions were also considered.
Results: At baseline, 33% of participants reported having initiated cannabis use, with an average of 7.6 days of use in the previous year. After three years, 77% reported having used cannabis, averaging 21.4 days in the previous year. Participants with greater ADHD symptoms had higher a rate of drop-out; however linear mixed effects models indicated a significant increase in cannabis use over time (p<0.0001). A significant three-way interaction between time, ADHD symptoms, and sex was found (p<0.0001). A median split analysis revealed that females reported more frequent cannabis use than males, yet effects of ADHD symptoms appeared greater for males. ADHD symptoms were associated with reduced activation in the intraparietal sulcus, left inferior frontal gyrus, cerebellum, and left orbitofrontal cortex during the stop-signal task. Further analyses will leverage latent growth models to explore the role of brain regions as mediators of the relationship between ADHD symptoms and cannabis use.
Conclusions: Elevated ADHD-related symptoms predict increased cannabis use frequency in young adults. Inhibitory control processes could represent early brain markers for cannabis misuse in young adults, informing potential treatment approaches.