Cannabis Use in a Community-Based Sample of Adults Diagnosed With ADHD: Prevalence, Impact on Symptoms, and Stimulant Side Effects.

Aim: Assess prevalence and correlates of cannabis use in adults with attention-deficit/hyperactivity disorder (ADHD) and explore its impact on comorbidities, symptoms, and side effects of prescription stimulants.

Methods: An anonymous online survey (April to July 2023) was emailed to 9,274 potential adult participants with a documented ADHD diagnosis, based on ICD-10 codes in the electronic medical record, which was secondarily verified by self-report. A total of 900 participants completed the survey. The 46-item survey covered demographics, medical history, prescription stimulant use, cannabis use, and its impact on ADHD symptoms and prescribed stimulant side effects, prescription stimulant misuse, cannabis use disorder, and health-related quality of life.

Results: In this large sample of adults diagnosed with ADHD, 75% reported ever using cannabis, with 41% reporting prior 30-day use. Groups of cannabis users were categorized into three groups; (1) no recent use (including never;  = 458); (2) non-daily use (<30 days in past month;  = 256); and (3) daily use (≥30 days in past month;  = 112). Compared to non-daily cannabis users, daily cannabis users showed comparable rates of prescription stimulant misuse (29% vs. 37%, OR = 1.39, 95% CI [0.87, 2.23],  = .166), and substance use disorder diagnoses (2% vs. 4%, OR = 1.54, 95% CI [0.43, 5.58],  = .508), but higher rates of cannabis use disorder (38% vs. 62%, OR = 2.67, 95% CI [1.69, 4.22],  < .001). Daily cannabis users were more likely to report fair or poor general health compared to non-daily cannabis users (24% vs. 11%, OR = 2.58, 95% CI [1.44, 4.64],  = .001). Daily cannabis users were more likely to report a comorbid diagnosis of anxiety (70% vs. 48%, OR = 2.55, 95% CI [1.59, 4.10],  < .001), depression (54% vs. 35%, OR = 2.24, 95% CI [1.42, 3.53],  < .001), bipolar disorder (15% vs. 5%, OR = 3.345, 95% CI [1.56, 7.15],  = .002), and post-traumatic stress disorder (PTSD) (30% vs. 14%, OR = 2.752, 95% CI [1.61, 4.71],  < .001), compared to non-daily cannabis users. Among participants who ever used cannabis, 278 (42%) reported they had used cannabis to manage their ADHD symptoms. Compared to non-daily cannabis users, daily cannabis users were significantly more likely to report that cannabis use improved ADHD symptoms of mental frustration (OR = 2.39, 95% CI [1.36, 4.19],  = .002) and impulsivity (OR = 1.69, 95% CI [1.07, 2.69],  = .026). Daily cannabis users were more likely to report that cannabis use worsened ADHD symptoms of inattention (OR = .59, 95% CI [0.36, 0.98],  = .043) compared to non-daily cannabis users. Participants reported mixed effects of cannabis use on anxiety: 156 noted improvements, while 34 reported worsening.

Conclusion: In this sample of adults diagnosed with ADHD, cannabis use was prevalent, with daily users showing higher rates of cannabis use disorder and co-morbid psychiatric diagnoses compared to non-daily users, highlighting the need for clinicians to screen for cannabis use disorder and psychiatric comorbidities. Cannabis users reported mixed effects of cannabis on ADHD symptoms and anxiety. Further research is warranted to understand the complex relationship between cannabis use, ADHD symptoms, and mental health.