Oxytocin is in the news again! Remember my post in February 2012 on Dr. Helen Fisher’s three stages of love? You don’t? Well, Dr. Fisher is a love guru (my words, not hers). She has spent more than 30 years studying the chemical effects of love, which led to her definition of the three stages of love: lust, romantic attraction and attachment. I’m going to revisit Fisher’s study here because the latest exciting study (we’ll get to that soon!) builds on her research.
Fisher recruited 49 people for MRI scans to study the circuitry of love. Seventeen people were newly in love, 15 had just been dumped, and 17 were still in love after an average of 21 years of marriage. Subjects looked at a photo of their sweetheart for one scan and a neutral photo for a second scan. Fisher’s team found a remarkable amount of brain activity when looking at these images, mainly at the ventral tegmental area (VTA). The VTA, located at the base of the brain, is basically the brain’s reward system. It is considered part of the reptilian core of the brain that is associated with wanting, craving, motivation, and focus. It is more powerful than the sex drive and it is the region of the brain that is active during a cocaine high.
In Fisher’s study, the chemical driving the VTA activity is oxytocin. According to Fisher’s three stages of love, oxytocin drives the third and most lasting stage, attachment. Oxytocin is an incredibly powerful hormone released during orgasm that makes couples feel close. It is actually a long-lasting chemical that can continue to flow in your brain. Oxytocin does not give the same highs as dopamine, rather it creates a feeling of contentment; hence, attachment.
In a new study, researchers again looked at the link between oxytocin and attachment. Like Fisher’s study, the German researchers also asked participants to look at photos. However, in this study, 20 unmarried men in multi-year relationships were asked to rank the attractiveness of pictures of their partner, acquaintances, a nonface control (i.e. a house), and strangers, before and after receiving a nasal spray of oxytocin or a placebo. The researchers ran two studies: the first a discovery, the second a replication. In the discovery study, the men looked at pictures of their partner, a stranger and a nonface control. In the replication study, researchers omitted the nonface control and instead used pictures of female acquaintances. In both studies, MRI scans showed increased activity in the VTA when the men looked at pictures of their partners after receiving a nasal spray of oxytocin. And, the men rated their partners as more attractive than the other women.
Understanding this chemical relationship helps explain the biological mechanisms of monogamy. People in long-term relationships have increased oxytocin levels. This increase in levels increases the psychological reward of spending time with the partner. Being with your partner can become an addiction.
Evolutionarily speaking, sexual monogamy can be costly for males and few other mammalian species (~3-5%) form such strong long-term attachments to their partners. The closest to humans are prairie voles, which bond in the same chemical manner as humans, driven by oxytocin. Which makes me sad knowing that my predator cat kills voles all the time, thus destroying countless happy families…
Frankly, this study makes me think of the classic movie, Love Potion No. 9 with Sandra Bullock and Tate Donovan. Bet it was oxytocin Madame Ruth gave Bullock and Tate. The researchers could make a mint off of the nose spray if they can get it bottled and into stores in time for Christmas!