Taxonicity of Cannabis Use Disorder: Findings From a Large Community Sample and an Inpatient Clinical Sample

Operational diagnostic definitions of drug addiction have evolved considerably over the last 20 years, including both a predominantly dimensional one (substance use disorder; Diagnostic and Statistical Manual of Mental Disorders, fifth edition) and a categorical one (substance dependence; International Classification of Diseases 11th revision). Although cannabis is among the most commonly used psychoactive drugs, few studies have directly evaluated whether the underlying structure of cannabis use disorder is categorical or dimensional or have done so in a clinical sample. Three taxometric procedures, mean above-minus below a cut (MAMBAC), maximum eigenvalue (MAXEIG), latent mode (L-Mode), were conducted in two data sets: (a) participants who reported cannabis use in the National Epidemiological Study and Alcohol and Related Conditions III, a large, representative sample of U.S. community adults (N = 3,623) and (b) patients reporting preadmission cannabis use in an inpatient substance use disorder treatment program in Ontario, Canada (N = 621). In the National Epidemiological Study and Alcohol and Related Conditions sample, comparison curve fit indices (CCFIs) supported dimensional structure: MAMBAC = 0.48; MAXEIG = 0.30; L-Mode = 0.43; M-CCFI = 0.40. Likewise, in the clinical sample, CCFI coefficients also supported dimensional structure: MAMBAC = 0.09, MAXEIG = 0.21, L-Mode = 0.26, M-CCFI = 0.19. These results suggest that the latent structure of cannabis addiction is a dimensional construct along a spectrum of severity rather than a dichotomous categorical construct. These findings are more consistent with the Diagnostic and Statistical Manual of Mental Disorders, fifth edition conceptualization compared to International Classification of Diseases 11th revision.