Researchers at the University of Pisa looked at the relationship between levels of oxytocin in the blood and anxiety in romantic relationships -- and what they found was counterintuitive.
First, they gave the 45 subjects in the study a questionnaire known as "Experiences in Close Relationships." This assesses the type of attachment a person experiences in a relationship. Psychologists who study attachment have pretty much agreed on four different attachment styles, although they sometimes use different names for them. The styles are: preoccupied, dismissing, fearful/avoidant and secure.
Preoccupied lovers are worried about losing their mates; they obsess over every little contretemps and can be really clingy. Dismissing people protect themselves from the pain of loss by not letting people get too close in the first place. Fearful/avoidant people crave closes relationships, but have difficulty trusting others.
Preoccupied and fearful/avoidant people score high on anxiety in relationships. Dismissive people have limited possible anxiety by refusing to allow anyone to matter too much, while secure people are, well, secure.
After categorizing the subjects attachment styles, for two months, the researchers sampled the participants' blood and measured the amount of oxytocin in each sample. (Although the mechanisms that release oxytocin into the blood are different from those that release it into the nervous system, several studies support a correlation between the two. It's relatively easy to measure plasma levels, and researchers have come to accept that what's circulating in the blood reflects what's running through the nervous system.)
The Pisa team looked for links between the presence and duration of romantic attachments, the amount of anxiety a test subject felt about his or her lover and the oxytocin level.
Because oxytocin is the hormone of peace and satisfaction, you might expect that the more secure people would have the highest levels. Instead, the Pisans found that the more anxious someone was about romance, the more oxytocin circulated in her veins.
In typical cautious scientific fashion, the researchers said this study "may constitute undoubtedly the first report of a link between oxytocin and that state of anxiety which is associated with romantic attachment in our species."
But why would the anxious lover have higher oxytocin levels than the secure one? The study doesn't show whether it's a cause or a consequence of the anxiety, but the researchers think that the brains of the worried lovers may release extra oxytocin to counteract all that stress.
Their hypothesis is that, for some of us, a romantic relationship is more stressful than comforting, so the body keeps boosting oxytocin so that we can overcome the fear of rejection or pain long enough to experience the pleasures of attachment.
This mechanism may have evolved, they think, to allow our remote ancestors to overcome their instinctual avoidance of strangers in order to meet, mate and reproduce.
Humans are obliged to face a paradox which is fundamental to the survival of the species: they are attracted to, courted by and breed with genetically unrelated individuals whom they would otherwise instinctively avoid. Romantic attachment is the psychological strategy which enables us to overcome neophobia and to mate with and create a strong, often life-long bond with a complete stranger, so that we may produce healthier offspring.
[At] the same time, we are rewarded by a deep sense of pleasure and satisfaction through the intervention of specific neural substrates …