Key Points:
- Oxytocin declines with age in mice, but whether it declines in humans requires further study.
- Oxytocin may mediate the cellular anti-aging effects of prosocial behavior.
- Supplementing with oxytocin can increase lean mass and help with strengthening social connections.
Oxytocin is sometimes referred to as the “love hormone” for its roles in social bonding, trust, empathy, and well-being. It is produced in the hypothalamus and released from the pituitary gland into the bloodstream, acting on multiple organs. As such, oxytocin facilitates several biological processes related to reproduction (e.g., lactation) and prosocial behavior.
Counteracting social isolation and maintaining social bonds is important for living the longest life possible. For this reason, scientists have begun to study how oxytocin levels change with age and how this affects sociability in older adults. Oxytocin can lead to the alleviation of key drivers of aging like shortened telomeres and oxidative stress, which may explain why prosocial behavior is associated with healthy aging.
Does Oxytocin Decline with Age?
Oxytocin has been shown to decline with age in mice, but the results from human studies are mixed. One study showed that older individuals have slightly lower baseline levels of oxytocin than younger individuals. In contrast, another study showed that oxytocin levels increase with age. However, in this study, oxytocin was measured after participants watched a heartfelt video to stimulate the release of oxytocin.
Additionally, researchers have measured oxytocin receptor gene levels in the brain, which may correlate with oxytocin secretion. The researchers found that oxytocin receptor expression peaked in early childhood, declined into adulthood, and then increased into older adulthood. These results have left scientists to speculate that the late-life increase in oxytocin receptor expression “could be a compensatory mechanism to stave off cognitive declines due to age-related deterioration of cognitive circuitry in the brain…”
Mitigating the Pro-Aging Effects of Social Isolation
Prairie voles are small rodents known for their socially monogamous behavior. To determine the effects of social isolation on cellular aging, scientists isolated prairie voles by placing them in a cage alone. This caused an increase in stress hormone levels and an acceleration of cellular aging, as shown by increased oxidative stress and reduced telomere length. The isolated voles also exhibited depressive-like behavior. However, daily injections of oxytocin prevented these negative consequences, suggesting that oxytocin mediates the beneficial anti-aging effects of social bonding.
In humans, one study showed an association between sexual intimacy and longer telomeres in women. Telomeres are repeated sequences of DNA at the ends of chromosomes that shorten with aging. Shorter telomeres are associated with an increased risk of death from cardiovascular, respiratory, digestive, musculoskeletal, and COVID-19-related complications. Considering that oxytocin is released following sexual intimacy, the increase in telomere length observed in women may have been mediated by oxytocin.
Physical and Social-Cognitive Benefits of Oxytocin
Higher oxytocin levels are associated with faster reaction times in younger and older individuals. In older adults, higher oxytocin levels are associated with improved memory, higher brain volume, decreased loneliness, a less depressed mood, and increased brain-derived neurotrophic factor (BDNF), a key molecule for memory and healthy brain aging. While correlational, these studies suggest that low oxytocin levels can lead to poor mental, cognitive, and brain health. If so, could supplementing with oxytocin counteract these deficits?
Several clinical trials have tested the effect of intranasal oxytocin on various age-related conditions, such as sarcopenic obesity. Sarcopenia is characterized by the age-related loss of muscle strength, mass, and quality. Sarcopenia often occurs in tandem with obesity, hence, sarcopenic obesity. In older adults with sarcopenic obesity, 8 weeks of intranasal oxytocin was shown to increase lean mass by about 5 pounds and reduce “bad” LDL cholesterol.
With age, our ability to recognize emotions from facial expressions diminishes. To determine the role of oxytocin in recognizing emotions based on facial expressions, scientists gave younger and older individuals oxytocin via intranasal administration. They found that oxytocin improved the facial recognition capacity of older males, but not older females or younger individuals. These findings suggest that oxytocin may counteract deficits in recognizing social cues, which can potentially help with strengthening social bonds.
A psychological predisposition that does not necessarily depend on age called attachment avoidance was reduced in older women who administered intranasal oxytocin. Attachment avoidance is when an individual avoids making strong social bonds with other people. Additionally, intranasal oxytocin improved the ability of young and older individuals to understand mental states and intentions (theory of mind), suggesting that oxytocin can improve social connectivity.
Dosage and Potential Side Effects of Intranasal Oxytocin
Most studies use 24 IU of intranasal oxytocin, often divided into 3 to 4 increments across the day. As far as potential side effects, intranasal administration of oxytocin has been shown to cause memory impairments, particularly in younger men (mostly in their twenties), such as impaired recall of words and impeded recall of visual cues. On the other hand, oxytocin has been shown to benefit young men, with studies showing it increases trust, improves facial expression recognition, and enhances theory of mind. Therefore, there may be trade-offs with oxytocin use, at least in younger men.
Overall, it seems that oxytocin could improve sociability, leading to stronger social bonds and broader social networks. Ultimately, this could result in improved mental and brain health, which are prerequisites for mitigating cognitive decline, neurodegeneration, and dementia.