Genes mediate the association between P3 amplitude and externalizing disorders


  • This research was supported in part by United States Public Health Service Grants AA09367, DA05147, and MH65137.

Address reprint requests to: Brian M. Hicks, who is now at the National Crime Victims Research and Treatment Center, Medical University of South Carolina, 165 Cannon Street, P.O. Box 250852, Charleston, SC 29425, USA, or Edward Bernat, Department of Psychology, University of Minnesota, 75 East River Road, Minneapolis, MN 55455, USA. E-mail: or, respectively.


Reduced P3 amplitude has been consistently linked to a spectrum of externalizing disorders. Utilizing data from a large sample of adolescent male twins (N=1196), we used biometric modeling to assess the genetic and environmental contributions to the association between reduced P3 amplitude and a general vulnerability to externalizing disorders. Externalizing vulnerability was indexed by a composite of symptoms of conduct disorder, adult antisocial behavior, and alcohol, nicotine, and drug dependence. The sample included two independent age cohorts, providing an internal replication of the findings. For the best-fitting model, genetic influences alone accounted for the association between P3 amplitude and externalizing disorders, with an estimated genetic correlation of rg=−.22. Results replicated across the two age cohorts and demonstrate that reduced P3 amplitude is a marker of the biological vulnerability to externalizing disorders.