Oxytocin, known as the “love hormone,” promotes feelings of trust and bonding, especially in women during and after childbirth. It may also enhance a person’s response to the placebo effect by way of patient-physician trust, according to a new study, which found that oxytocin enhanced the painkilling effect of a placebo on participants exposed to painful heat stimuli.
Participants who were given an intranasal oxytocin spray were more likely to believe that the burning sensation on their forearms was relieved from a placebo cream when compared to participants who inhaled a saline spray. “We hypothesize that oxytocin might have increased the believability of the instructions by the study physician,” the researchers wrote, according to MedPage Today.
The researchers approached the study with the intent of finding a way to enhance placebo effect in patients who weren’t as susceptible to it on their own. “Some people have a very large placebo effects and others don’t, and it would be very nice to have a pharmaceutical option to help people who are not so good at producing placebo analgesia on their own to compliment the standard medical treatment,” Dr. Ulrike Bingel, lead researchers of the study and a neurologist at University Duisberg-Essen, Germany, told HealthDay.
Eighty men in their 20s participated in the study. The researchers randomly assigned each participant to either the oxytocin spray or the saline spray, and then applied cream to each of their forearms. They told the participants that the cream on one of their forearms was a strong pain-reliever and that the other cream was a control, however, both creams were the same, and contained no active ingredients.
Forty-five minutes later, the participants were subjected to a heat stimuli, which gradually increased in strength until participants rated their pain at a 60 on a 100-point scale. Once each participant was leveled off at a pain rating of 60, the researchers applied the particular heat intensity 10 different times for 20 seconds each, every minute.
Participants rated pain on the arm that had with the control cream at 59.96 for the oxytocin group and 58.31 for the saline group. However, when it came to pain ratings on the arms with the pain-relieving cream, participants in the oxytocin group rated pain at a 47.11, while those in the saline group rated it at a 51.23. By subtracting the pain ratings from the pain-relieving site by the pain ratings from the control site, the difference was 12.84 for the oxytocin group compared to 7.08 for the saline group.
“To our knowledge, our study provides the first experimental evidence that placebo responses can be pharmacologically enhanced by the application of intranasal oxytocin,” the authors wrote, according to a statement. The authors also accredited the response to the possibility that the hormone also reduced anxiety and stress.
Oxytocin has also been shown to improve people’s confidence in social situations. A 2011 study found that participants felt more extraverted and social after inhaling an oxytocin spray than before exposure to the hormone. Another study from earlier this year found that oxytocin helped students subjected to social rejection bounce back more easily, allowing them to trust others even though they had just been disrespected.
Oxytocin helps forge closeness between one individual and another, Larry Young, director of the Conte Center for Oxytocin and Social Cognition at Emory University, in Atlanta, told HealthDay. “When you’re looking another person in the eyes and you’re really caring about the other person there, you’re releasing oxytocin.”
Source: Kessner, S, Sprenger C, Bingel U, et al. Effect of Oxytocin on Placebo Analgesia: A Randomized Study. JAMA. 2013.