By Margarita Nahapetyan
Chatting with a girlfriend appears to do wonders for a woman's health and mood, says a new study by a University of Michigan. The experts discovered that feeling emotionally close to a girlfriend and other social contacts, increases levels of the hormone progesterone, helping to boost a woman's overall well-being and alleviate anxiety and stress.
In the new study, the investigators led by a principal author Stephanie Brown, analyzed the link between interpersonal closeness and progesterone levels in the saliva of 160 female college students. In the beginning of the study, the experts measured the levels of progesterone and of the stress hormone cortisol in the women's saliva, and also gathered information about their menstrual cycles. All the participants were asked whether they were using hormonal contraceptives or other hormonally active drugs.
In order to control for daily variations in hormone levels, all the sessions were performed between noon and 7 o'clock in the evening. In a random order the women were assigned to partners and were asked to perform either a task that aimed to boost feelings of emotional closeness or a task that was emotionally neutral. In the emotionally neutral task, the ladies needed to proofread a botany manuscript together. After the 20-minute tasks were completed, the women played a computerized cooperative card game with their partners, and then the experts examined their progesterone and cortisol levels one more time.
The results revealed that the levels of progesterone in the participants who took part in the emotionally close task remained the same or were elevated, whereas those in the emotionally neutral group demonstrated the decreased levels of the hormone. The women's levels of cortisol did not change in a similar way. In the study, progesterone was used as a marker for oxytocin, a hormone linked to relationship trust and pair-bonding. Oxytocin, however, can only be measured through spinal fluid or through expensive and complex brain scanning methods, such as positron emission tomography scans. Progesterone can be measured through simple saliva samples and may be related to oxytocin.
One week later, the women returned to the second part of an experiment to play a computerized card game with their original partners again. After the game they had their saliva tested for progesterone and cortisol, and were also asked how willing they would be to risk their life for their partner. Researchers found that increased progesterone levels were more likely to predict a willingness to say they would risk their lives for their partners.
'During the first phase of the study, we found no evidence of a relationship between progesterone and willingness to sacrifice,' Brown said. 'But a week later, increased progesterone predicted an increased willingness to say you would risk your life to help your partner.'
The researchers said that the results of their study coincide with a new evolutionary theory of altruism, according to which the hormonal basis of social bonds enables individuals to put self-interest behind when needed in order to promote the well-being of another person, as well as when taking care of children or helping ailing family members or friends. The research also helps explain why social contact appears to contribute to improved health - a relationship first identified nearly 20 years ago by U-M sociologist James House.
The study is published in the June issue of the journal Hormones and Behavior.