It’s been nearly four decades since I traveled to the University of Illinois with my wife to visit her former biology professor, Lowell Getz. I was bemused by his interest in voles—small rodents resembling mice, of which there is a multitude of species. I remember watching them scurrying along the fence rows. Why anyone would want to devote a career to studying them escaped me. In what has become a common experience, I was taken aback by my ignorance when I discovered recently that Getz and his colleagues1 were pioneering research in my main area of interest, attachment theory.
Differences between two species of voles have garnered the attention of attachment researchers. Prairie voles are monogamous; they form enduring pair bonds, analogous to romantic relationships in us humans. Prairie voles provide biparental care to their young, and they’re loyal: if they lose a mate, they don’t take another partner. They get attached. In contrast, nonmonogamous meadow voles are promiscuous; they don’t form partner preferences. They don’t get attached. The differences between prairie voles and meadow voles are neatly tied to the neuropeptide oxytocin and a closely related neuropeptide, vasopressin.2 Both neuropeptides facilitate pair bonding, although oxytocin plays a more important role in females and vasopressin in males.
Oxytocin facilitates maternal behavior—in delivery by facilitating intrauterine contractions, and after birth by triggering milk letdown. Oxytocin also promotes infants’ attachment to their mother. Thus oxytocin plays a widespread role in attachment, facilitating infant attachment, maternal bonding and adult attachment (pair bonds). Handily, oxytocin stimulates brain reward circuits, including those involving endogenous opioids (natural narcotic-like substances in the brain). Thus oxytocin renders attachment relationships pleasurable and soothing.3
A quick look at the literature
Research on the influence of oxytocin on human social behavior has been made easy by the fact that intranasal inhalation boosts brain levels of oxytocin temporarily—a few puffs in each nostril will do. Here’s a brief sampling of recent studies demonstrating the social effects of sniffing oxytocin:
- When we see a threatening picture such as an angry face, a brain structured called the amygdala immediately becomes activated. Our amygdala not only detects threat but also orchestrates our fear response. Thus trauma researcher Bessel van der Kolk dubbed the amygdala the brain’s smoke detector. Recently, researchers administered oxytocin or placebo to participants before they were shown threatening pictures. Compared to placebo, oxytocin decreased amygdala activity and dampened the fear response.4 Under the influence of oxytocin, we can feel less threatened by others.
- Persons with social phobia typically show exaggerated amygdala responses to threatening social cues such as fearful faces. Researchers found that administering oxytocin normalized amygdala responses in persons with social phobia, that is, reducing their hyperactive amygdala responses.5
- Researchers study trust by putting participants into the role of “investors” and giving them the option of transferring part of their holdings to a person placed in the role of the “trustee.” Investors can maximize their gains by transferring more money to trustees—but only if trustees reciprocate by sharing their earnings. Under the influence of oxytocin, investors show greater trust and willingness to take social risks: they transfer more money to trustees.6
- Simon Baron-Cohen developed the Reading the Mind in the Eyes Test to measure participants’ capacity to understand others’ emotional states, a component of mentalizing ability.7 This is a multiple-choice test in which participants are shown photographs of the eye region of the face and asked to identify what emotion the individual is feeling. Sniffing oxytocin improved performance on this test, implying that oxytocin is an empathy amplifier.8
- Researchers exposed a group of men to a threatening social situation, namely, a mock job interview conducted by a panel.9 Just prior to the interview, one group had the benefit of social support, that is, the presence of their best friend. The other group had no such support. Some participants also sniffed oxytocin prior to the interview. Participants’ level of distress was measured by their level of stress hormones after the interview. Both social support and oxytocin decreased stress, but their combination was best. In short, oxytocin enhanced the stress-reducing function of social support.
- One of the studies of attachment that has made the greatest impression on me was conducted at the Baylor College of Medicine by our colleagues Lane Strathearn and Peter Fonagy and their colleagues.10 The study compared mothers who showed evidence of secure attachment in adulthood with those who were insecurely attached. Compared with those who showed insecure attachment, securely attached mothers showed higher levels of oxytocin after interacting with their infant in a play situation. In a later phase of the study, the mothers were shown pictures of their infants’ happy faces as well as their sad faces. Compared to the insecure mothers, those who were secure showed higher levels of activity in brain-reward circuits when viewing pictures of their infants—not only when the infants were happy but also when they were sad. In contrast, when viewing the face of their sad infant, the insecure mothers showed activation in brain areas suggesting higher levels of emotional distress as well as efforts to inhibit this distress. The secure mothers’ characteristically higher levels of oxytocin when interacting with their infant were believed to contribute to this difference, enabling them to stay engaged with their distressed infants. The mother’s capacity for engagement is crucial, because it enables infants to become securely attached—confident that their mother will be psychologically attuned to their distress, that is, mentalizing.
For those of us who place a high value on secure attachment relationships, oxytocin seems to be a natural wonder drug. Indeed, it’s been dubbed the hormone of love. Musing about the potential of psychotherapy to promote attachment, renowned neuroscientist Jaak Panksepp wondered if therapists and their clients might benefit from intranasal oxytocin administered prior to therapy sessions.11 Was Panksepp serious? I can’t tell from the way he wrote it. But if you see therapists and their clients sniffing something prior to therapy sessions, you’ll know someone took him seriously. I wonder if oxytocin might enhance the effects of POT (Plain Old Therapy). Using your imagination, the possible applications to human affairs are limitless.
On the other hand …
Unfortunately, additional research douses this utopian vision with some cold water while also shedding light on the sheer complexity of oxytocin’s influence on relationships:
- Shelly Taylor and her colleagues12 found that oxytocin levels were elevated in women whose current attachment relationships were in a state of distress. Moreover, oxytocin’s counterpart in men, vasopressin, was elevated when their attachment relationships were stressed. The authors speculated that these prosocial neuropeptides become elevated in the context of relationship distress to provide a biological signal to the distressed individual to seek support in other relationships.
- As expected, Jennifer Bartz and colleagues13 found that administering oxytocin led males to remember their mother as having been more caring and close. Yet there was an important caveat: this result held true only for those males who showed a general pattern of secure attachment in their current relationships. Under the influence of oxytocin, males who were insecurely (anxiously) attached remembered their mother as less caring and remembered being less close to her in childhood. The authors speculated that administering oxytocin activates attachment needs and that this activation has different effects depending on the security of attachment.
- In another study, Jennifer Bartz and colleagues14 studied the effects of administering oxytocin on trusting behavior in a game where participants played for money and had the option of cooperating or competing. Recall that oxytocin enhanced trusting behavior in a study I described earlier in this post.6 Bartz did a similar study but included participants with borderline personality disorder, a disorder associated with insecure attachment and unstable relationships, often owing to a fear of abandonment. In contrast to the usual findings, for persons with borderline personality disorder, administering oxytocin decreased trust and cooperation, an effect that was most pronounced in those participants who showed a high level of anxiety in attachments in combination with an aversion to closeness.
This glimpse of a burgeoning research literature shows that oxytocin plays a significant role in attachment—typically a salutary role. And it underscores a main function of attachment, namely, its role in providing a feeling of safety and security in the face of emotional stress. Most important in my mind is Strathearn and colleagues’ finding that securely attached mothers are able to remain positively engaged with their infants when their infants are distressed, and oxytocin may play a role in this crucial maternal ability. But the research also shows that sniffing oxytocin might heighten relationship problems for persons who are insecurely attached.
Perhaps we should not be surprised that there is no shortcut to secure attachment for those who most need it. As a society, we’re always on a quest for quick fixes and panaceas—drugs prominent among them. But secure attachment must be acquired the old-fashioned way, by good parenting, good relationships and—when enhancements are needed—POT (Plain Old Therapy).
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2. Young LJ, Wang Z. The neurobiology of pair bonding. Nature Neuroscience. 2004; 7:1048-1054.
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6. Kosfeld M, Heinrichs M, Zak PJ, Fischbacher U, Fehr E. Oxytocin increases trust in humans. Nature. 2005; 435:673-676.
7. Baron-Cohen S, Wheelwright S, Hill J, Raste Y, Plumb I. The “Reading the Mind in the Eyes” Test Revised Version: A study with normal adults, and adults with Asperger Syndrome or high-functioning autism. Journal of Child Psychology and Psychiatry. 2001; 42:241-251.
8. Domes G, Heinrichs M, Michel A. Oxytocin improves “mind-reading” in humans. Biological Psychiatry. 2007; 61:731-733.
9. Heinrichs M, Baumgartner T, Kirschbaum C, Ehlert U. Social support and oxytocin interact to suppress cortisol and subjective responses to psychosocial stress. Biological Psychiatry. 2003; 54:1389-1398.
10. Strathearn L, Fonagy P, Amico J, Montague PR. Adult attachment predicts maternal brain and oxytocin response to infant cues. Neuropsychopharmacology. 2009:1-12.
11. Panksepp J. Brain emotional systems and qualities of mental life: From animal models of affect to implications for psychotherapeutics. In: Fosha D, Siegal DJ, Solomon MF, eds. The healing power of emotion: Affective neuroscience, development and clinical practice. New York: Norton; 2009:1-26.
12. Taylor SE, Saphire-Bernstein S, Seeman TE. Are plasma oxytocin in women and plasma vasopressin in men biomarkers of distressed pair-bond relationships? Psychological Science. 2010;21:3-7.
13. Bartz JA, Zaki J, Ochsner KN, Bolger N, Kolevzon A, Ludwig N. Effects of oxytocin on recollections of maternal care and closeness. PNAS. 2010; 107:21371-21375.
14. Bartz JA, Simeon D, Hamilton H, et al. Oxytocin can hinder trust and cooperation in borderline personality disorder. Social Cognitive and Affective Neuroscience. 2010; November:1-8.