Salivary testosterone and aggression, delinquency, and social dominance in a population-based longitudinal study of adolescent males Irene van Bokhoven a , Stephanie H.M. van Goozen b, ⁎ , Herman van Engeland a , Benoist Schaal c , Louise Arseneault d , Jean R. Séguin e , Jean-Marc Assaad e , Daniel S. Nagin f , Frank Vitaro e , Richard E. Tremblay e a Department of Child and Adolescent Psychiatry, UMCU, Utrecht, The Netherlands b School of Psychology, Cardiff University, UK c Centre Européen des Sciences du Goût (CNRS), Dijon, France d Social, Genetic and Developmental Psychiatry Research Center, Institute of Psychiatry, University of London, UK e Research Unit on Children’s Psycho-Social Maladjustment, University of Montreal, Canada f H.J. Heinz III School of Public Policy and Management, Carnegie Mellon University, Pittsburgh, USA Received 5 April 2005; revised 9 February 2006; accepted 12 February 2006 Available online 24 April 2006 Abstract Testosterone (T) has been found to have a stimulating effect on aggressive behavior in a wide range of vertebrate species. There is also some evidence of a positive relationship in humans, albeit less consistently. In the present study we investigated the relationship between T and aggression, dominance and delinquency over time, covering a period from early adolescence to adulthood. From a large population-based sample (n = 1.161) a subgroup of 96 boys was selected whose behavior had been assessed repeatedly by different informants from age 12 to 21 years, and who had provided multiple T samples over these years of assessment. On the whole, a decrease in aggressive and delinquent behavior was observed in a period in which T rises dramatically. Boys who developed a criminal record, had higher T levels at age 16. In addition, positive associations were observed between T and proactive and reactive aggression and self-reported delinquent behavior. Over the pubertal years different forms of aggressive and delinquent behavior were positively related to T, which may indicate that specific positive links are dependent on the social setting in which this relationship is assessed. © 2006 Elsevier Inc. All rights reserved. Keywords: Testosterone; Aggression; Delinquency; Dominance; Pubertal development Introduction Testosterone (T), the most important male sex hormone, affects not only physical but also behavioral masculinization. For example, T has been found to increase aggressive behavior in a wide range of vertebrate species (Archer, 1988). Studies in male rodents show that competitive or intermale aggression increases at puberty, a time in which T levels dramatically rise. Also, administration of T results in an increase in aggression (Brain, 1979), whereas it is reduced by (chemical) castration (see Van Goozen et al., 1995 for results in humans). In human adults, T has been found to be related to delinquency, drug abuse (Dabbs and Morris, 1990) and criminal violence (Dabbs et al., 1995; Ehrenkranz et al., 1974; Kreuz and Rose, 1972; Strong and Dabbs, 2000), as well as to conduct problems in childhood (Dabbs and Morris, 1990). However, Bain et al. (1987) found no difference in T between men charged for aggressive or non-aggressive crimes. It is clear, therefore, that in humans the evidence is at best suggestive of a positive relationship (Archer, 1991). Much less information exists about the relationship between T and aggressive behavior in children and adolescents. Some studies found a positive relationship between T and physical and Hormones and Behavior 50 (2006) 118 – 125 www.elsevier.com/locate/yhbeh ⁎ Corresponding author. School of Psychology, Cardiff University, PO Box 901, Cardiff CF10 3AT, UK. Fax: +44 2920 874858. E-mail address: VanGoozenS@Cardiff.ac.uk (S.H.M. van Goozen). 0018-506X/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.yhbeh.2006.02.002