The lay concept of conduct disorder: Do nonprofessionals use syndromal symptoms or internal dysfunction to distinguish disorder from delinquency?

Background: Conduct disorder (CD) must be distinguished from nondisordered delinquent behaviour to avoid false positives, especially when diagnosing youth from difficult environments. However, the nature of this distinction remains controversial. The DSM-IV observes that its own syndromal CD diagnostic criteria conflict with its definition of mental disorder, which requires that symptoms be considered a manifestation of internal dysfunction to warrant disorder diagnosis. Previous research indicates that professional judgments tend to be guided by the dysfunction requirement, not syndromal symptoms alone. However, there are almost no data on lay conceptualizations. Thus it remains unknown whether judgments about CD are anchored in a broadly shared understanding of mental disorder that provides a basis for professional-lay consensus. Objective: The present study tests which conception of CD, syndromal-symptoms or dysfunction-requirement, corresponds most closely to lay judgments of disorder or nondisorder and compares lay and professional judgments. We hypothesized that lay disorder judgments, like professional judgments, tend to presuppose the dysfunction requirement. Method: Three lay samples (nonclinical social workers, nonpsychiatric nurses, and undergraduates) rated their agreement that youths described in clinical vignettes have a mental disorder. All vignettes satisfied DSM-IV CD diagnostic criteria. Vignettes were varied to present syndromal symptoms only, symptoms suggesting internal dysfunction, and symptoms resulting from reactions to negative circumstances, without dysfunction. Results: All lay samples attributed disorder more often to youths whose symptoms suggested internal dysfunction than to youths with similar symptoms but without a likely dysfunction. Conclusions: The dysfunction requirement appears to reflect a widely shared lay and professional concept of disorder.