Psychic Structure of Opioid Addiction: Impact of Lifetime Psychiatric Problems on SCL-90-based Psychopathologic Dimensions in Heroin-dependent Patients

Background: By applying a Principal Component Analysis (PCA) to the items of the SCL-90 checklist, we previously investigated the psychopathologic structure of individuals with heroin addiction, finding a 5-factor aggregation of psychological/psychiatric symptoms: "Worthlessness and Being trapped," "Somatic Symptoms," "Sensitivity-Psychoticism," "Panic-Anxiety," and "Violence-Suicide." Our studies on this subject did not, however, explore the possible impact of comorbid psychiatric conditions on 5 psychopathologic dimensions listed above. The aim of the present study is to verify whether there is any difference in these 5 dimensions between heroin-addicted patients with (PC-HA) or without (NPC-HA) known lifetime psychiatric problems. Methods: A total of 1195 patients with heroin dependence entering a residential therapeutic community treatment were assigned to one of the 5-factor solutions yielded by Principal Component Analysis on the basis of the highest z score obtained. Differences between NPC-HA and PC-HA patients in the frequency of the 5 psychopathologic dimensions and in their severity were then analyzed by means of univariate and multivariate analyses. Results: All the SCL-90 factor scores were, from a statistical viewpoint, significantly higher in PC-HA than in NPC-HA patients, but the only statistically significant differences in the frequency of the 5 psychopathological dimensions were those observed in the case of "Panic-Anxiety," which turned out to be higher in the PC-HA group. Stepwise discriminant analysis showed that the severity of "Somatic Symptoms" and "Panic-Anxiety" made these 2 factors the only ones that successfully discriminated between NPC-HA and PC-HA patients. The other SCL-90-based psychopathologic dimensions were unable to improve the value of the discrimination. Conclusions: On the basis of our results, the SCL-90-defined structure of opioid addiction may be considered to be only partly dependent on the presence of a "psychiatric" condition. This observation adds to the previous ones that go to show the stability of the above aggregations of symptoms, irrespectively of other demographic and clinical characteristics, as well as active involvement with heroin abuse or the kind of treatment chosen. When the available evidence is considered as a whole, it seems to support the trait-dependent, rather than state-dependent, nature of the proposed factorial dimensions of the psychopathology of opioid addiction.