Humans are highly social. Not only do we experience isolation as stressful, but it can also cause changes at the cellular level that lead to accelerated aging. Loneliness can, quite literally, age you faster. However, a recent study shows that a hormone called oxytocin can protect against this aging effect. But how does isolation get under the skin in the first place?
Cellular aging is a process in which cells gradually stop dividing, leaving the body vulnerable to damage and disease. A marker for this process is the shortening of the ends of DNA strands, called telomere caps. Telomere caps protect the DNA molecule, kind of like the plastic tips at the end of shoelaces protect the shoelace from fraying. These telomere caps get shorter and shorter with each cell division until they get too short and the cell stops dividing.
Previous studies have found that glucocorticoids can shorten telomeres, triggering the cellular aging process to speed up. Glucocorticoids are hormones that increase in response to stressful experiences like isolation. But oxytocin may protect against this effect. Oxytocin is released during positive social interactions and is associated with emotional attachment. It can reduce the negative effects of isolation by blocking the stress response. Oxytocin may even be able to slow down cellular aging by preventing telomere shortening.
Researchers decided to test this by giving oxytocin treatments to socially isolated prairie voles. Prairie voles were chosen for this study because, like humans, they are highly social animals and respond negatively to long periods of isolation. In this study, 60 prairie voles were placed in cages either by themselves or with a sibling for 42 days. They were randomly assigned to receive either daily injections of oxytocin, daily injections of an inactive substance, or no injections at all. On days 0, 21, and 42 researchers collected blood samples to measure telomere length and levels of glucocorticoids.
Unfortunately, blood samples collected at the beginning of the study were not preserved properly and the DNA in these samples were damaged. As a result, researchers could not measure telomere length at the beginning of the study. This limits their findings in several ways. First, they couldn’t tell whether groups had different telomere lengths on day 0. Secondly, they didn’t know whether telomere length changed between day 0 and day 21. Despite this, researchers were still able to measure telomere length from the other blood samples.
They found that oxytocin does in fact slow down cellular aging! Isolated voles that were given daily injections of oxytocin had longer telomeres on day 42 than isolated voles that did not receive oxytocin. In fact, their telomere length was the same as voles that had spent 42 days with their sibling. Oxytocin also reduced signs of stress. Isolated voles had high levels of glucocorticoids on day 21 and 42, a sign of being stressed. But those treated with oxytocin had glucocorticoid levels similar to those that were not isolated.
This study is the first to demonstrate that oxytocin is protective against the aging effects of social isolation in prairie voles. Studying isolation in social species provides a useful model for how this process may work in humans. While we must be cautious when applying results from animal models to humans, there is reason to think these results are useful. Isolation is a stressful experience for humans as well as prairie voles; one that has been shown to lead to faster aging.
A simple way to combat the negative effects of isolation is through social support, which previous research has shown to increase oxytocin levels. While more work is needed, it seems as though social support may be an effective strategy for slowing down cellular aging. This is particularly important as loneliness becomes more of an issue in our disconnected societies.