Self-ratings of ADHD symptoms in adults I: Factor structure and normative data

Background: Although well-standardized behavior rating scales are routinely utilized in children for evaluations of Attention Deficit Hyperactivity Disorder (ADHD), comparable measures for adults with ADHD symptomatology have been sparse. Based on current literature and clinical experience, nine aspects of adult ADHD functioning provided initial hypotheses regarding factor structure and scale items for a new scale for self-rating of symptoms by adults suspected of having ADHD. Method: A normative sample of 839 subjects and a clinical sample of 167 subjects completed ratings of an initial pool of 93 items. Results: Exploratory and confirmatory factor analyses suggested a four-factor structure involving 42 items. These factors include Inattention/Cognitive Problems, Hyperactivity/Restlessness, Impulsivity/Emotional Lability, and Problems with Self-Concept. Conclusion: The scale appears to cover the core features of ADHD as seen in children and adolescents, while adding content unique to adult expression of the ADHD syndrome. The new scale (Conners' Adult ADHD Rating Scale, or CAARS) may provide a useful dimensional measurement system for research and clinical applications.