Science Watch

Oxytocin has been on a joy ride for 20 years, ever since animal studies first linked the hormone to bonding between mother and newborn, as well as between mating adults. Dubbed the “cuddle” or “love” hormone by the popular press, more recently it has earned attention for its role in promoting trust.

One company, Vero Labs in Boca Raton, Fla., has even put it in a cologne-like spray, marketed as “Liquid Trust”: Fifty dollars buys a two-month supply that promises consumers “confidence in a bottle,” according to its website.

But can oxytocin live up to the hype? Research does link it to increased trust, social bonding and even a predisposition to donate to charity. It’s these positive influences that make researchers hopeful that it could help treat mental health disorders, including autism, social anxiety disorder and schizophrenia. Small-scale, preliminary studies show that a sniff of the hormone enables people with autism to better read social cues and allays social anxiety among those with social anxiety disorder. Some physicians are so convinced in the promise of oxytocin, they’ve started prescribing it to children with autism.

That makes oxytocin researchers nervous. Too many questions remain unanswered, including how it works and under what circumstances. On top of those concerns, recent studies suggest that oxytocin may also have a darker side: For some people it might actually decrease trust and sociability and, depending on the context, high levels of the hormone might be a sign that a close relationship is troubled.

“People got carried away with the idea of the cuddle hormone,” says University of California, Los Angeles, psychologist Shelley E. Taylor, PhD. Her work on oxytocin suggests that the hormone is high in women whose relationships are in distress. “It’s never a good idea to map a psychological profile onto a hormone; they don’t have psychological profiles.”

The good and bad

Most hormones don’t influence behavior directly. Rather, they affect thinking and emotions in variable ways. Researchers have several theories about the specific processes that oxytocin engages. In particular, they suggest that by decreasing anxiety and prompting us to get close to someone else, oxytocin allows the brain to pay closer attention to subtle social cues.

“Oxytocin is not the love hormone,” says Larry Young, PhD, of Center for Translational Social Neuroscience at Emory University. “It’s tuning us into social information and allowing us to analyze it at a higher resolution.”

When oxytocin was first discovered in 1909, it was thought mostly to influence a mother’s labor contractions and milk let-down. Then, in the 1990s, research with prairie voles found that giving them a dose of oxytocin resulted in the formation of a bond with their future mate.

Since then, work on oxytocin has exploded in both animals and humans. The number of papers with oxytocin as an index term on PsycINFO increased from just 17 in 1990 to 118 in 2010. Studies are examining not only the specifics of how oxytocin works in the brain, but also its influence on behavior in animals and humans, including bonding, trust, anxiety and social understanding.

In a series of studies, Claremont Graduate University economist Paul Zak, PhD, for example, showed that giving people oxytocin via nasal spray increases their trust of others. He also found that higher levels of oxytocin are associated with giving more money to charity, and, in women, having more friends, having better romantic relationships and having more sex. He calls it the “molecule of connection.”

But new research suggests that oxytocin may also enhance negative social cues. Taylor has evidence that oxytocin rises not only in women who are in good, affectionate relationships, but also in women who have distressed relationships. In the latter case, she believes oxytocin may be signaling the need to seek other social contact.

“We don’t think it’s signaling, ‘stay close to that person,’ it’s signaling ‘stay close to someone’ because your bonds are threatened. Get social contact from somewhere,” Taylor says.

More evidence of oxytocin’s downside comes from Mount Sinai School of Medicine psychologist Jennifer Bartz, PhD. In a study published online in November in Social Cognitive and Affective Neuroscience, she and her colleagues examined whether oxytocin might boost trust and cooperation, as measured with a well-studied economic game, among men and women with borderline personality disorder, who tend to have volatile relationships. She found that rather than increasing trust and teamwork, a dose of oxytocin decreased those feelings compared with a placebo.

In another study, published last December in the Proceedings of the National Academy of Sciences (Vol. 107, No. 48), Bartz found that men who had stable, well-attached relationships remembered their childhood relationship with their mothers as more caring and close when they received oxytocin compared with when they didn’t. In contrast, men who were insecure in their current relationships remembered their childhood relationship with their mothers as less caring and close when they received oxytocin. Of course, the hormone could simply be helping men remember their childhoods more accurately, or it may be coloring their memory search, drawing attention to memories that are more salient to the men based on their current mindset, negative or positive, says Bartz. Only more research will tell.

Controlled substance

Even with so much unknown about how and when oxytocin works, many researchers believe that someday it could be useful for treating disorders that affect people’s ability to relate to one another.

In a brain imaging study, for example, University of Cambridge neuroscientist Pradeep Nathan, PhD, showed that, in people with social anxiety disorder, oxytocin calmed an exaggerated response to fearful faces typically seen in their amygdalas. Although the hormone didn’t have a similar effect on how people actually felt, the researchers suspect it would after more prolonged treatment, just as other psychiatric medications often take time to work. (Neuropsychopharmacology, Vol. 35.)

If further research establishes that oxytocin does have therapeutic value, Young believes it will be best used as part of behavioral treatments in very controlled settings due to its highly context-dependent effect. With a condition such as autism, for example, clinicians might administer oxytocin doses that last about three hours, and work with patients on understanding social cues during that time. The hope is that those social cues will have more meaning for patients while the oxytocin is working and that the learning, in turn, might make lasting changes in the brain.

Still, with so many unknowns, most researchers don’t recommend that people start trying oxytocin to treat themselves or their children. It’s only available through a prescription but, says Young, there have been many rumors suggesting that physicians have started giving it to some people to treat autism as well as social anxiety.

He thinks they’re being premature.

“Most studies in humans give a single dose,” says Young. “There’s no research on what repeated use of the hormone might do.”

Beth Azar is a writer in Portland, Ore.