The neuroscience of affiliation: Forging links between basic and clinical research on neuropeptides and social behavior Jennifer A. Bartz ⁎ , Eric Hollander Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1230, New York, NY 10029, USA Received 16 May 2006; revised 15 June 2006; accepted 21 June 2006 Available online 1 August 2006 Abstract Animal studies point to the role of two neuropeptides–oxytocin and vasopressin–in the regulation of affiliative behaviors including mating, pair-bond formation, maternal/parenting behavior, and attachment. These findings may have important implications for understanding and treating clinical disorders marked by social deficits and/or disrupted attachment. This review focuses on advances made to date in the effort to forge links between basic and clinical research in the area of neuropeptides and social behavior. The literature on oxytocin and its involvement in stress response, affiliation, and prosocial behavior is reviewed, and the implications of these findings for such disorders as autism as well as other social and stress-related disorders including social phobia, post-traumatic stress disorder, and some personality disorders are considered. Finally, unresolved issues and directions for future research are discussed. © 2006 Elsevier Inc. All rights reserved. Keywords: Neuropeptides; Oxytocin; Social behavior; Translational research; Autism Introduction Noting the ubiquity of abnormal social attachments in “virtually every form of psychopathology” (p. 726), Insel (1997) called attention to the importance of research investiga- ting the neurobiology involved in social bond formation. Animal studies support the role of two neuropeptides, oxytocin and vasopressin, in the regulation of affiliative behaviors including mating, pair-bond formation, maternal/parenting behavior, and attachment. This article reviews advances made to date in the effort to forge links between basic and clinical research in the area of neuropeptides and social behavior. Because Lim and Young (see our companion article in this issue) review the animal literature in this area in detail, this article will focus on the implications of the findings from animal studies as well as those from studies of healthy humans regarding neuropeptides and social behavior for clinical disorders. Moreover, although findings from animal studies point to the involvement of oxytocin and vasopressin in social behavior, we will concentrate primarily on oxytocin because most of the studies conducted thus far in humans have focused on oxytocin. In the first part of this review, we examine the involvement of oxytocin in stress response, affiliation, and prosocial behavior; we touch briefly on the findings from animal studies, but our primary focus is studies of healthy humans. In the second part of this review, we address the clinical implications of these findings as well as of the findings from animal studies. In particular, we address the relevance of oxytocin for such disorders as autism as well as other social and stress-related disorders including social phobia, obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), and borderline personality disorder (BPD). Finally, we conclude with a discussion of unresolved issues and directions for future research. Oxytocin, stress, and social affiliation Before reviewing the evidence to date regarding the role of oxytocin in humans, it should be noted that research in this area has been hampered because of the methodological difficulties Hormones and Behavior 50 (2006) 518 – 528 www.elsevier.com/locate/yhbeh ⁎ Corresponding author. E-mail address: jennifer.bartz@mssm.edu (J.A. Bartz). 0018-506X/$ - see front matter © 2006 Elsevier Inc. All rights reserved. doi:10.1016/j.yhbeh.2006.06.018