The neuroscience of affiliation: Forging links between basic and clinical research on neuropeptides and social behavior
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 investigating 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.
Section snippets
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 involved. Whereas animal researchers have had a number of tools at their disposal (e.g., the ability to centrally administer oxytocin and oxytocin antagonists, manipulate the expression of oxytocin by knocking out specific genes, and directly assess oxytocin mRNA), researchers investigating the role of oxytocin
Oxytocin and autism
According to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR, American Psychiatric Association, 2000), autism is a developmental disorder characterized by abnormalities in speech and communication, impaired social functioning, and repetitive behaviors and restricted interests. A number of researchers have suggested that oxytocin and vasopressin may be implicated in the etiology of autism given that deficits in social interaction and affiliation are a
Unresolved issues and future directions
In conclusion, most of the studies investigating the neurobiology of social behavior and affiliation have used animal models; however, recent methodological advances have allowed researchers to begin to ask more rigorous questions concerning the neurobiology of human social behavior. The findings to date have been encouraging and suggest that oxytocin and possibly vasopressin, which have been implicated in animal studies, are also involved in human affiliation. In addition to shedding light on
Acknowledgments
Preparation of this article was supported by grants from the National Institute of Health 5 U54 MH066673-03 STAART Autism Centers of Excellence, Beatrice and Samuel A. Seaver Foundation, National Institute on Neurological Disorders and Stroke, National Institute on Drug Abuse, and the Orphan Products Division of the Food and Drug Administration. We gratefully acknowledge Evdokia Anagnostou for comments on an earlier version of this article. Dr. Hollander is listed as an inventor on a patent for
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