Journal of Abnormal Child Psychology, Vol. 23, No. 6, 1995 Developmental Change in Attention-Deficit Hyperactivity Disorder in Boys: A Four-Year Longitudinal Study Elizabeth L. Hart 1,6 Benjamin B. Lahey, 2 Rolf Loeber, 3 Brooks Applegate, 4 and Paul J. Frick 5 One hundred six clinic-referred boys meeting criteria for DSM-III-R attention-deficit hyperactivity disorder (ADHD) (mean age 9.4 years) were assessed annually for 4 years using structured interviews of multiple informants. Hyperactivity-impulsivity symptoms declined with increasing age, but inattention symptoms did not. Rather, inattention declined only from the first to the second assessment and remained stable thereafter in boys of all ages. The rate of decline in hyperactivity-impulsivity symptoms was independent of the amount and type of treatment received. Boys who still met criteria for ADHD in Years 3 and 4 were significantly younger, more hyperactive-impulsivg and more likely to erhibit conduct disorder in Year I than boys who no longer met criteria in Years 3 and 4. Attention-deficit hyperactivity disorder (ADHD) has been studied using prospective longitudinal designs more than any other disorder arising in childhood (Gittelman, Mannuzza, Shenker, & Bonagura, 1985; Klein & Mannuzza, 1991; Loney, Whaley-Kahn, Kosier, & Conboy, 1983), but the course of developmental change in ADHD is still not dear. The issues that most seriously interfere with our ability to map the developmental course Manuscript received in final form July 27, 1994. This study was supported by grant 1-R01-MH42529 from the National Insitute of Mental Health to Rolf Loeber and Benjamin B. Lahey. 1yale UniversityChild Study Center, New Haven, Connecticut 06520. 2University of Chicago School of Medicine, Chicago, Illinois 60637. 3University of Pittsburgh, Pittsburgh, Pennsylvania 15213. 4University of Miami, Coral Gables, Florida 35487-0348. ~University of Alabama, Tuscaloosa,Alabama 33146. 6Address all correspondenceto Elizabeth L Hart, Ph.D., Yale Child Study Center, 230 South Frontage Road, P.O. Box 207900, New Haven, Connecticut 06520-7900. 729 0091-0627/95/12011-0729507.50/0 © 1995 Plenum Publishing Corporation