Journal of Abnormal Child Psychology, Vol. 20, No. 2, 1992 Frontal Lobe Functions in Attention Deficit Disorder With and Without Hyperactivity: A Review and Research Report Russell A. Barkley, 1,2 Gail Grodzinsky, 1 and George J. DuPaul I We review 22 neuropsychological studies of frontal lobe functions in children with attention deficit disorder with and without hyperactivity (ADD/+H, ADD/-H). Some measures presumed to assess frontal lobe dysfunctions were not reliably sensitive to the deficits occurring in either form of ADD. Tests of response inhibition more reliably distinguished ADD/+H from normal children. Where impairments were found on other tests between ADD and nor- mal subjects, they were highly inconsistent across studies and seemed strongly related to age of the subjects and possibly to the version of the test employed. Other methodological differences across studies further contributed to the dis- crepant reports. The co-morbidity of other disorders, such as learning dis- abilities (LD) and conduct problems, with ADD may be an additional confounding factor in some, though not all, of these studies. In a separate study, children with ADD/+H (n = 12) were then compared on frontal lobe tests to three other groups: ADD/-H (n = 12), LD but no ADD (n = 11), and normal children (n = 12) statistically covarying for differences in conduct problems across groups. Most measures did not distinguish among these groups. Both ADD groups made more omission errors on a Continuous Per- Manuscript received in final form September 9, 1991. This research was supported by NIMH grant MH41464 and by funds from the Department of Psychiatry, University of Massachusetts Medical Center. The authors are grateful to Judy Tessier and Ellen Mintz-Lennick for their assistance with some of the data collection and scoring. The comments of Virginia Douglas on an earlier draft of this paper are greatly appreciated. 1Departments of Psychology and Neurology, University of Massachusetts Medical Center, Worcester, Massachusetts. 2Address all correspondence, including requests for reprints, to Russell A. Barkley, Ph.D., Department of Psychiatry, University of Massachusetts Medical Center, 55 Lake Avenue North, Worcester, Massachusetts 01655. 163 0091-0627/92/0400-0163S6.50/0 9 1992 Plenum Publishing Corporation