title: Attention-deficit/hyperactivity disorder dimensionality: the reliable 'g' and the elusive 's' dimensions.
abstract: The best structural model for attention-deficit/hyperactivity disorder (ADHD) symptoms remains a matter of debate. The objective of this study is to test the fit and factor reliability of competing models of the dimensional structure of ADHD symptoms in a sample of randomly selected and high-risk children and pre-adolescents from Brazil. Our sample comprised 2512 children aged 6-12 years from 57 schools in Brazil. The ADHD symptoms were assessed using parent report on the development and well-being assessment (DAWBA). Fit indexes from confirmatory factor analysis were used to test unidimensional, correlated, and bifactor models of ADHD, the latter including "g" ADHD and "s" symptom domain factors. Reliability of all models was measured with omega coefficients. A bifactor model with one general factor and three specific factors (inattention, hyperactivity, impulsivity) exhibited the best fit to the data, according to fit indices, as well as the most consistent factor loadings. However, based on omega reliability statistics, the specific inattention, hyperactivity, and impulsivity dimensions provided very little reliable information after accounting for the reliable general ADHD factor. Our study presents some psychometric evidence that ADHD specific ("s") factors might be unreliable after taking common ("g" factor) variance into account. These results are in accordance with the lack of longitudinal stability among subtypes, the absence of dimension-specific molecular genetic findings and non-specific effects of treatment strategies. Therefore, researchers and clinicians might most effectively rely on the "g" ADHD to characterize ADHD dimensional phenotype, based on currently available symptom items.
authors: Attention Deficit/Hyperactivity Disorder Program, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350 - Room 2202, Porto Alegre, 90035-003, Brazil. flavia_scs@yahoo.com.br.|Federal University of Rio Grande do Sul, Porto Alegre, Brazil. flavia_scs@yahoo.com.br.
authors: Flávia
authors: F
authors: Wagner
authors: University of Kentucky, Lexington, USA.
authors: Michelle M
authors: MM
authors: Martel
authors: National Institute of Developmental Psychiatry for Children and Adolescents - CNPq, Porto Alegre, Brazil.|Federal University of São Paulo, São Paulo, Brazil.
authors: Hugo
authors: H
authors: Cogo-Moreira
authors: Attention Deficit/Hyperactivity Disorder Program, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350 - Room 2202, Porto Alegre, 90035-003, Brazil.|Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
authors: Carlos Renato Moreira
authors: CR
authors: Maia
authors: National Institute of Developmental Psychiatry for Children and Adolescents - CNPq, Porto Alegre, Brazil.|Federal University of São Paulo, São Paulo, Brazil.
authors: Pedro Mario
authors: PM
authors: Pan
authors: Attention Deficit/Hyperactivity Disorder Program, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350 - Room 2202, Porto Alegre, 90035-003, Brazil.|Federal University of Rio Grande do Sul, Porto Alegre, Brazil.|National Institute of Developmental Psychiatry for Children and Adolescents - CNPq, Porto Alegre, Brazil.|São Paulo University, São Paulo, Brazil.
authors: Luis Augusto
authors: LA
authors: Rohde
authors: Attention Deficit/Hyperactivity Disorder Program, Hospital de Clínicas de Porto Alegre, Ramiro Barcelos, 2350 - Room 2202, Porto Alegre, 90035-003, Brazil. gsalumjr@gmail.com.|Federal University of Rio Grande do Sul, Porto Alegre, Brazil. gsalumjr@gmail.com.|National Institute of Developmental Psychiatry for Children and Adolescents - CNPq, Porto Alegre, Brazil. gsalumjr@gmail.com.
authors: Giovanni Abrahão
authors: GA
authors: Salum
mesh_terms: D000293:Adolescent; D001288:Attention; D001289:Attention Deficit Disorder with Hyperactivity / Q000175:diagnosis* / Q000453:epidemiology*; D001938:Brazil / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D007175:Impulsive Behavior; D008297:Male; D011594:Psychometrics; D015203:Reproducibility of Results; D012574:Schools / Q000639:trends; D012919:Social Behavior
keywords: ADHD; Bifactor model; Confirmatory factor analysis; Hierarchical; Impulsivity