‘Love hormone’ oxytocin increases as we age, new research shows

People whose brains release more of the oxytocin hormone are friendlier to others and more satisfied with their own lives, according to a new US study.

What’s more, the release of oxytocin increases with age in many people, researchers wrote in the scientific journal Frontiers in Behavioral Neuroscience in April.

Oxytocin, sometimes referred to as the “love hormone,” is a neurotransmitter produced in the brain that plays a strong role in the relationships of couples and in maternal bonding, among other things.

However it also influences our social interactions with all people around us, and can be triggered by activities such as touch, listening to music or doing exercises.

The team of researchers, led by neuroeconomist Paul Zak of Claremont Graduate University, included 103 participants between the ages of 18 and 99 in their study.

They were shown a video about a boy with cancer, which researchers from the group had previously found stimulates the release of oxytocin in the brain. Before and after the video, blood was drawn from the subjects to measure the change in oxytocin levels.

“Participants in our study who released the most oxytocin were more generous to charity when given the opportunity and performed many other helping behaviours,” lead author Zak said, noting that his team gave participants the choice to donate some of their earnings from the study to a childhood cancer charity. This was then used to measure their immediate prosocial behaviour.

In addition, data on the subjects’ emotional state was collected to assess their overall life satisfaction. To test prosocial behaviour, the scientists also asked whether the participants had made donations in money or in kind and had done voluntary work in the past year.

“We also found that the release of oxytocin increased with age and was positively associated with life satisfaction.” That means, according to the research, older people have higher levels of oxytocin and are, on average, more helpful and satisfied than younger people.

However, it is not clear from the study whether the oxytocin is the result or the cause of the observed behaviours. The authors themselves emphasise that they cannot establish a causal relationship between oxytocin, prosocial behaviour and subjective attitudes.

“There are likely factors in addition to the release of oxytocin that cause people to share money, donate to charity, participate in religious activities and have high satisfaction with life that we were unable to measure and should be explored in future research,” the researchers write.

In addition, the subject group was very small and geographically homogeneous and not all participants responded to the video. The study authors also did not take into account that older people sometimes have more time and money at their disposal than younger people.

The exact way oxytocin works is scientifically disputed. It is proven that the hormone plays an important role in the relationship between mother and child: Oxytocin induces labour, stimulates milk production and strengthens the relationship with the offspring.

In addition, it can reduce stress and anxiety, make people more empathetic, is important for sexual arousal and can promote bonding in couples as well as trust between people.

The latter aspect was demonstrated by an experiment conducted by the economist Michael Kosfeld and psychologist Markus Heinrichs. Subjects who were administered oxytocin through the nose had significantly more trust in other people than those who were given a placebo.

The study, which was published in Nature in 2005 and in which Paul Zak was also involved, triggered a great deal of research on the hormone.

However, it quickly became apparent that this chemical messenger’s mode of action is more nuanced than initially assumed and that labelling it as a “love hormone” falls short of explaining its true role in our social behaviour.

For example, studies have suggested that under certain circumstances and in certain situations, oxytocin could make people more distrustful and malicious.

Research by Dutch psychologist Carsten de Dreu even showed that the hormone does increase a person’s willingness to trust and cooperate – but only within the group to which one feels a sense of belonging, while other groups can be devalued. This thesis was clearly contradicted by the work of psychologist Heinrichs and colleagues.

Most recently, hopes of using an oxytocin nasal spray as an autism medication were met with disappointment. A US study with almost 300 children and adolescents concluded that the hormone did not change their social behaviour for the better.