J Psychiatry Neurosci 2013; 39(1): 22-30
Sylco S. Hoppenbrouwers, PhD; Danilo R. De Jesus, MD; Yinming Sun, MSc; Tania Stirpe, PhD; Dennis Hofman, PhD; Jeff McMaster, MD; Ginny Hughes, BSc; Zafiris J. Daskalakis, MD, PhD*; Dennis J.L.G. Schutter, PhD*
Hoppenbrouwers, Hofman, Schutter — Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Utrecht, the Netherlands; de Jesus, Sun, Daskalakis — Centre for Addiction and Mental Health, Schizophrenia program, Toronto, Ont.; Stirpe, Hughes — Correctional Service of Canada, Central Ontario District (Parole), Psychology Department, Toronto, Ont.; McMaster — Centre for Addiction and Mental Health; Law and Mental Health Program, Toronto, Ont., Canada
*These authors contributed equally to this work.
Background: Psychopathic offenders inevitably violate interpersonal norms and frequently resort to aggressive and criminal behaviour. The affective and cognitive deficits underlying these behaviours have been linked to abnormalities in functional interhemispheric connectivity. However, direct neurophysiological evidence for dysfunctional connectivity in psychopathic offenders is lacking.
Methods: We used transcranial magnetic stimulation combined with electroencephalography to examine interhemispheric connectivity in the dorsolateral and motor cortex in a sample of psychopathic offenders and healthy controls. We also measured intracortical inhibition and facilitation over the left and right motor cortex to investigate the effects of local cortical processes on interhemispheric connectivity.
Results: We enrolled 17 psychopathic offenders and 14 controls in our study. Global abnormalities in right to left functional connectivity were observed in psychopathic offenders compared with controls. Furthermore, in contrast to controls, psychopathic offenders showed increased intracortical inhibition in the right, but not the left, hemisphere.
Limitations: The relatively small sample size limited the sensitivity to show that the abnormalities in interhemispheric connectivity were specifically related to the dorsolateral prefrontal cortex in psychopathic offenders.
Conclusion: To our knowledge, this study provides the first neurophysiological evidence for abnormal interhemispheric connectivity in psychopathic offenders and may further our understanding of the disruptive antisocial behaviour of these offenders.
Submitted Mar. 5, 2012; Revised Oct. 23, Dec. 10, 2012, Feb. 23, 2013; Accepted Apr. 5, 2013.
Acknowledgements: We thank all volunteers whose participation was essential to the completion of this work. We also thank the reviewers for their very helpful and insightful comments. Y. Sun declares having received a Master’s Awards from the Canadian Institutes of Health Research (CIHR). Z.J. Daskalakis declares being supported in part by a CIHR Clinician Scientist Award, an operating grant from the Ontario Mental Health Foundation, and a Constance and Stephen Lieber through a National Alliance for Research on Schizophrenia and Depression (NARSAD) Lieber Young Investigator award. D.J.L.G. Schutter declares being supported by an Innovational Research Grant (VIDI 452–07–012) from the NWO.
Competing interests: Z.J. Daskalakis declares external funding from Neuronetics Inc. and Aspect Medical Inc. He also declares having received travel support from Pfizer Inc. and external funding from Neuronetics Inc., Aspect Medical, Inc. and Pfizer, Inc. No other competing interests declared.
Contributors: S. Hoppenbrouwers, J. McMaster, Z. Daskalakis and D. Schutter designed the study. S. Hoppenbrouwers, D. de Jesus, T. Stirpe and G. Hughes acquired the data, which S. Hoppenbrouwers, Y. Sun and D. Hofman, analyzed. S. Hoppenbrouwers and Z. Daskalakis wrote the article, which all authors reviewed and approved for publication.
Correspondence to: D.J.L.G. Schutter, Department of Experimental Psychology, Helmholtz Institute, Utrecht University, Domplein 29, 3512 JE Utrecht, Netherlands; firstname.lastname@example.org