Objective: It has been argued that Axis I and Axis II disorders diagnosed in substance users refer to substance-induced conditions rather than to independent psychiatric conditions; this argument will be referred to as the substance-related artifact hypothesis. Furthermore, Axis II symptoms co-occurring with Axis I disorders have been attributed to the contamination of personality assessment by mood and/or anxiety state effects (the trait-state artifact hypothesis). The present study is the first to prospectively examine the validity of these two hypothesized "artifacts" in substance users.
Method: In 276 individuals (57.6% female) applying for substance use treatment, current substance use disorders, mood/anxiety disorders and Axis II disorders were diagnosed using semistructured interviews both at baseline and at 1-year follow-up. The substance-related artifact hypothesis is tested by examining the covariation between recovery from substance use disorders on the one hand and recovery from and/or improvement of mood/anxiety and Axis II disorders on the other hand. The trait-state artifact hypothesis is tested by examining the covariation between recovery from mood/anxiety disorders on the one hand and recovery from and/or improvement of Axis II disorders on the other hand.
Results: Recovery from substance use disorders covaried with recovery from and improvement of mood/anxiety disorders, but not with recovery from or improvement of Axis II pathology. Furthermore, recovery from mood/anxiety disorders covaried with recovery from and improvement of personality disorders, in particular Cluster C disorders.
Conclusions: Results from this study suggest that mood/anxiety disorders, but not personality disorders, diagnosed among people with substance use disorder may partly reflect substance-related artifacts. Furthermore, this study provides evidence for the contention that semistructured interview assessment of Axis II, at least without inquiry on an item-by-item basis, is susceptible to contamination by mood/anxiety state effects.