Objective: The objective of this study was to conduct latent class analysis (LCA) of ADHD symptoms to characterize the underlying structure of ADHD. Method: Participants were recruited from September 2012 to January 2015 from the Department of Psychiatry of Asan Medical Center, Seoul, Korea. Diagnoses of ADHD and comorbid psychiatric disorders were confirmed with the Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL). We performed LCA of ADHD symptoms in those who had (n = 141, age = 8.1 ± 2.3 years, 106 boys) and did not have (n = 82, age = 9.1 ± 2.5 years, 40 boys) ADHD. Results: A three-class solution was found to be the best model, revealing classes of children with mostly combined and hyperactive/impulsive subtypes of ADHD (Class 1), non-ADHD (Class 2), and inattentive subtype of ADHD (Class 3). Conclusion: The three-class solution with LCA supports a two-factor two-class structure of ADHD symptoms.
Keywords: ADHD; CPT; IQ; latent class analysis; youth.