Childhood experiences can leave a lasting imprint on a person’s willingness to help strangers, but a naturally occurring hormone called oxytocin might have the power to temporarily shift these tendencies. A recent study published in Translational Psychiatry suggests that a dose of oxytocin can increase altruistic donations in adults who experienced higher levels of childhood adversity, producing the opposite effect in those with fewer adverse early experiences. The findings provide evidence that early life events shape how the brain responds to social chemicals later in life.
Altruistic behavior involves choosing to help others even when it comes at a personal cost. Past research indicates that experiencing adversity during childhood, such as emotional neglect or physical abuse, is linked to lasting reductions in this type of generous behavior.
Seeking to uncover the biological factors behind this trend, scientists designed a new experiment. The research team was led by Nina Marsh, a researcher in the Department of Psychiatry and Psychotherapy at the Carl von Ossietzky University of Oldenburg in Germany, and Vanessa Jeske, alongside colleagues from the University of Bonn and Georgetown University.
“What fascinates me about altruism is that helping another person—particularly a stranger at a personal cost—is anything but self-evident,” Marsh said. “Yet we see it across societies and throughout human history. Understanding what enables people to transcend immediate self-interest is therefore not only a question about social behavior, but also about something fundamental to human coexistence. It is precisely this complexity that makes the study of human altruistic behavior so fascinating to me.”
People who encounter severe early stressors often develop a heightened sensitivity to social threats, which can make it more difficult for them to form trusting bonds or engage in acts of generosity as adults.
“One question that has fascinated me is how our earliest life experiences shape our willingness to help others later in life,” Marsh noted. “Adverse childhood experiences are remarkably complex and can affect people in very different ways. While their links to mental health have been studied extensively, much less is known about how they relate to prosocial behavior in adulthood.”
To understand if this decline in prosocial behavior can be temporarily altered, the researchers looked to oxytocin. Oxytocin is a hormone produced in the brain that plays a role in regulating social behaviors like empathy, bonding, and trust. “We therefore wanted to explore whether childhood adversity might shape how people respond to oxytocin during altruistic decision-making—and what happens in the brain during those decisions,” Marsh said.
The scientists recruited 54 healthy young men, with an average age of about 25, for a placebo-controlled experiment. Participants were screened to ensure they had no current or past psychiatric illnesses. The research team also measured and controlled for several baseline factors, including anxiety, depressive symptoms, autistic traits, empathy, personal income, and how often the participants had donated money in the past year.
Participants were randomly assigned to receive either a nasal spray containing oxytocin or a placebo spray with no active ingredients. Neither the participants nor the scientists running the experiment knew who received which spray. About 40 minutes after taking the nasal spray, participants completed a monetary donation task while lying inside a high-resolution brain scanner known as an MRI. This specific timing was chosen to capture the peak behavioral and neural effects of the nasal spray.
During the brain scan, participants were given an initial endowment of 60 Euros. They viewed 60 short profiles on a screen, with 40 profiles describing a stranger in a state of need and 20 describing individuals with no specific need. For each scenario, participants had up to 15 seconds to choose to donate anywhere from zero to one Euro in 10-cent increments. They were informed that any money they chose to give would be deducted from their final payout.
In the placebo group, the scientists found that early life experiences predicted donation amounts. Participants who reported higher levels of childhood adversity donated an average of just 8.22 Euros in total. Participants with lower levels of childhood adversity donated more than twice that amount, averaging 20.01 Euros.
The oxytocin spray produced contrasting effects depending on a person’s background. For those with a history of higher childhood adversity, oxytocin nearly doubled their altruistic behavior, raising their average total donation from 8.22 Euros to 15.68 Euros. For participants who experienced lower childhood adversity, oxytocin had the opposite effect. In this low-adversity group, the hormone cut their average donations by 53 percent, dropping their total from 20.01 Euros down to 9.46 Euros.
This bidirectional result suggests that the hormone does not act as a simple switch that uniformly turns on generosity. “Our findings once again challenge the popular idea to refer to oxytocin as a simple ‘love hormone,'” Marsh told PsyPost.
“Oxytocin does not uniformly promote prosocial behavior—its effects are much more complex. We know that individual characteristics as well as environmental and biographical factors can influence both the direction and magnitude of oxytocin’s behavioral effects. Our study suggests that early life experiences are another important part of this picture.”
Rather than acting as a universal booster for giving, oxytocin appears to tune a person’s sensitivity to social cues based on their existing baseline. “Perhaps the most important takeaway is that early life experiences do not determine who we become,” Marsh said. “But they may shape how we respond to social and neurobiological signals later in life.”
For those whose social sensitivity was lowered by early adversity, oxytocin might boost their attention to others’ needs into an optimal range for helping. For those who already have high social sensitivity, extra oxytocin might make them overly sensitive or hesitant, reducing their willingness to give. “In our study, oxytocin did not simply make people ‘more altruistic,'” Marsh noted. “Its effects differed depending on participants’ childhood experiences, highlighting how biology and individual life history can interact in shaping social behavior.”
Brain scans helped explain these behavioral shifts by tracking functional connectivity, which is a measure of how well different brain areas communicate with one another in real time. The scientists focused on the connection between the medial prefrontal cortex and the middle cingulate cortex. The medial prefrontal cortex is a brain area involved in taking another person’s perspective and regulating emotions. The middle cingulate cortex is a region that helps detect socially relevant information and guides adaptive responses.
In the placebo group, higher childhood adversity was associated with stronger communication between these two brain regions, and this heightened neural connectivity corresponded with lower donation amounts. When given oxytocin, this communication pattern reversed. The hormone reduced the connectivity between these regions in the high-adversity group, which aligned with their increased willingness to donate money to strangers.
The researchers combined the behavioral data and the brain connectivity data into a single predictive mathematical model. This combined model explained almost 47 percent of the variation in how much money people chose to donate. This finding indicates that altruistic behavior is not just a psychological trait but is deeply rooted in the architecture and communication patterns of the brain.
Relying on self-reported questionnaires to measure childhood adversity means that memories of early experiences might be incomplete or influenced by a person’s current mood. “Childhood adversity is highly complex and heterogeneous: different types, timing, duration, and severity of adverse experiences may have very different effects, which cannot be fully captured by a single retrospective measure,” Marsh pointed out. “Our findings therefore provide an empirical foundation that describes associations with reported childhood adversity.”
Because the study only included healthy young men, the findings do not necessarily apply to broader populations. “Also, our sample consisted exclusively of healthy men, so the findings need to be replicated in larger and more diverse samples, particularly including women,” Marsh said. “Finally, our findings should not be interpreted as evidence that oxytocin can ‘reverse’ the effects of childhood adversity or as supporting its clinical use for this purpose.”
Observing how the brain’s social networks operate under various types of stress will help clarify exactly how early life events alter social processing.
“My long-term research asks a much broader question: What are the conditions under which empathy-based altruism unfolds?” Marsh explained. “I want to better understand how biographical, environmental, and neurobiological factors interact to shape our willingness to help others. This means looking beyond individual factors in isolation and studying how our experiences and biology jointly shape empathy, trust, cooperation, and altruistic behavior.”
The study, “Early life adversity shapes neural and behavioural responses to oxytocin during altruistic decision-making,” was authored by Nina Marsh, Vanessa Jeske, Mari Babasiz, Angela Herscheid, Ann-Kathrin Kreuder, Rüdiger Stirnberg, Tony Stoecker, Abigail A. Marsh, Johannes Schultz, and René Hurlemann.