An Examination of Personality Structure in Dual Diagnosis Patients: Similarities and Differences Compared to Substance Use Disorder Patients and Healthy Control.

The prevalence of comorbidity among different disorders, known as Dual Diagnosis (DD), is common in clinical practice. Particularly, preliminary studies indicate high co-occurrence rates of personality disorders (PDs) and substance use disorders (SUDs). Previous research has shown the relevance of investigating different pathological organizations in personality profiles among individuals with DD compared to those with single psychiatric diagnoses. Despite its clinical relevance, very little research has been conducted on the topic. To this end, we evaluated the personality structure of 147 individuals (Mean age = 35.8 ± 10.9), categorized into three distinct samples: 60 participants from the community, 45 outpatients with SUDs, and 42 inpatients with DD of SUDs and co-occurring PD. Participants were interviewed through the Structured Interview of Personality Organization-Revised (STIPO-R), assessing Kernberg's dimensional model of personality. Analysis of variance revealed that SUD and DD patients shared poorly integrated identity and object relations, rigid and primitive defenses, poorly integrated moral values, and higher self-directed aggression levels compared to individuals from the community sample. Moreover, DD patients were characterized by an impaired sense of self, overall maladaptive defenses, higher levels of other-directed aggression, and narcissism. Findings suggest that the SUD and the DD patients exhibit similar patterns limited to some aspects of personality organization. However, results highlight the specific role of some dimensions in shaping DD pathological personality organization, with consequent implications for diagnosis and treatment.