Longitudinal study of CBCL Scales at 18 months and 2.5 years old. ADHD, attention deficit/hyperactivity disorders; BF, breastfeeding; SF, standard infant formula; EF, experimental infant formula; Op. Def, oppositional defiant. Generalized linear mixed model of repeated measures for direct scores for Internalizing Problems (A), Externalizing Problems (B), Total Problems (C), ADHD (D), and Oppositional Defiant Problems (E) in COGNIS participants. Mean normative values: total problems = 33.5; externalizing problems = 14; internalizing problems = 9; ADHD = 5.5 and oppositional defiant problems = 4 [33].