A Dual Diagnosis Typology to Improve Diagnosis and Treatment of Dual Disorder Patients

Abstract

A dual diagnosis typology was developed with three subtypes. Type I is a primary psychiatric disorder with substance use only when psychiatrically symptomatic (self-medication). Type II is a primary substance use disorder with substance-induced psychiatric symptoms. Type III is psychiatric and substance use disorders of long duration that are co-occurring or present at different times. Type III is considered the “true” dual disorder state. This typology was found to be reliable and have consensual validity. It was used with a standardized interview and clinical interview plus questions designed to determine the subtype with patients in psychiatric and substance abuse outpatient programs and with state hospital inpatient dual disorder patients. The dual disorder subtypes found in the psychiatric outpatient programs were: Type I, 21%; Type II, 9%; and Type III, 70%. In the substance abuse programs were found: Type I, none; Type II, 37%; and Type III, 63%. The subtypes in the state psychiatric patients were: Type I, 14%; Type II, 47%; and Type III, 39%. This method was found to be relatively easy to apply; it also increased staff interest in the dual disorder population and improved differential diagnoses and targeted interventions.

Keywords:

• diagnosis of dual disorders
• dual diagnosis
• dual disorder