J Psychiatry Neurosci 2012;37(6):389-98
Michael C. Stevens, PhD; Emily Haney-Caron, BA
Stevens, Haney-Caron — Olin Neuropsychiatry Research Center, Institute of Living at Hartford Hospital, Hartford, Conn.;
Stevens — Department of Psychiatry, Yale University School of Medicine, New Haven, Conn.
Background: Previous studies of brain structure abnormalities in conduct disorder and attention-deficit/hyperactivity disorder (ADHD) samples have been limited owing to cross-comorbidity, preventing clear understanding of which structural brain abnormalities might be specific to or shared by each disorder. To our knowledge, this study was the first direct comparison of grey and white matter volumes in diagnostically “pure” (i.e., no comorbidities) conduct disorder and ADHD samples.
Methods: Groups of adolescents with noncormobid conduct disorder and with noncomorbid, combined-subtype ADHD were compared with age- and sex-matched controls using DARTEL voxel-based analysis of T1-weighted brain structure images. Analysis of variance with post hoc analyses compared whole brain grey and white matter volumes among the groups.
Results: We included 24 adolescents in each study group. There was an overall 13% reduction in grey matter volume in adolescents with conduct disorder, reflecting numerous frontal, temporal, parietal and subcortical deficits. The same grey matter regions typically were not abnormal in those with ADHD. Deficits in frontal lobe regions previously identified in studies of patients with ADHD either were not detected, or group differences from controls were not as strong as those between the conduct disorder and control groups. White matter volume measurements did not differentiate conduct disorder and ADHD.
Limitations: Our modest sample sizes prevented meaningful examination of individual features of ADHD or conduct disorder, such as aggression, callousness, or hyperactive versus inattentive symptom subtypes.
Conclusion: The evidence supports theories of frontotemporal abnormalities in adolescents with conduct disorder, but raises questions about the prominence of frontal lobe and striatal structural abnormalities in those with noncomorbid, combined-subtype ADHD. The latter point is clinically important, given the widely held belief that ADHD is associated with numerous frontal lobe structural deficits, a conclusion that is not strongly supported following direct comparison of diag nostically pure groups. The results are important for future etiological studies, particularly those seeking to identify how early expression of specific brain structure abnormalities could potentiate the risk for antisocial behaviour.
Submitted Oct. 14, 2011; Revised Feb. 27, Mar. 26, 2012; Accepted Mar. 28, 2012.
Acknowledgements: This study was funded by National Institute of Mental Health grant K23 MH070036 (M.C. Stevens) and supported in part by R01 MH080956 (M.C. Stevens). Appreciation is offered to the Connecticut Court Support Services Division program and research staff who collected and helped to prepare the data for analysis.
Competing interests: As above for M.C. Stevens. None declared for E. Haney-Caron.
Contributors: M.C. Stevens designed the study, acquired the data and reviewed the article. Both he and E. Haney-Caron analyzed the data, wrote the article and approved its publication.
Correspondence to: M.C. Stevens, Olin Neuropsychiatry Research Center, Hartford Hospital / The Institute of Living, 200 Retreat Ave.,
Whitehall Bldg., Hartford CT 06106; email@example.com