Substance Use Disorders in Adolescence Exist along Continua: Taxometric Evidence in an Epidemiological Sample.

A longstanding nosological question in the clinical literature is whether substance use disorders (SUDs) are best conceptualized as categorical or dimensional phenomena. Taxometric analysis is a statistical approach uniquely developed to address this issue. To date, no taxometric studies have been conducted with SUDs in adolescents. The current taxometric study investigated the latent structure of SUDs in adolescents for four different substances: marijuana, analgesics, hallucinogens, and inhalants. Interview-derived data for DSM-IV SUD symptoms were drawn from the National Survey on Drug Use and Health, pooled across the years 2004 to 2013 (unweighted n = 181,573; 48.92% female). Two mathematically non-redundant taxometric methods (MAMBAC [mean above minus below a cut] and MAXEIG [maximum eigenvalue]) were conducted with the data for respondents who had used the substance under study at least once in the past 12 months, or on 5 separate days in the case of marijuana (unweighted ns = 4900 to 17,517). Consistent evidence emerged in support of a dimensional solution across the analyses for all four substances (mean comparison curve fit index = 0.129 to 0.301). The current findings are consistent with the view of SUDs in adolescents as continuous syndromes rather than discrete entities. These findings are also consistent with theoretical conceptualizations of SUDs as having multi-causal etiologies, and have implications for current diagnostic conceptualizations of SUDs.