Comorbidity between Substance Use Disorder (SUD) and other psychiatric disorders, known as Dual Diagnosis, is an issue of growing interest in Mental Health. The high association between Personality Disorders (PD) and substance use is reported in scientific literature. However, not many studies have been published regarding the prevalence of this disorder in a psychiatric unit. AIMSTo determine the prevalence of substance abuse among patients with a Personality Disorder in a psychiatric unit.

A retrospective descriptive study was carried out among all patients admitted to our psychiatric unit during one year. The data collected from the discharge clinical records of patients were: demographic variables, personal psychiatric history and substance use, urine tests and clinical diagnoses at discharge.

We obtained a sample of 334 patients. There was comorbidity between Mental Disorder and SUD in 10.17% of subjects; including 4% diagnosed with Personality Disorder (80% belong to Cluster B). 53.3% of patients with PD substance abuse was reported. Excluding nicotine dependence and benzodiazepines, the most common substances used were cannabis (50%), alcohol (37.5%) and cocaine (25%).

This study shows that Personality Disorder is the Mental Disorder most commonly associated with SUD, among inpatients in our psychiatric unit. In order to detect cases of Dual Diagnosis, we suggest optimize recording in clinical history substance use and systematic urine tests in all patients admitted, which would benefit from specific treatment for their condition.