We know that being stressed affects the way we treat others — especially, adversely. But a new study, published in The Journal of Neuroscience this month, explores the brain processes that drive even the most empathetic of people to be more selfish and less kind when they’re stressed.

To reach this conclusion, researchers asked the participants to make donations before they were asked to undertake a stressful task; they were asked to donate things again after the task was over. While people who were found to have high empathy donated more than the others did before undergoing the stressful task, their charitability declined sharply afterward. Interestingly, the charitability of people who hadn’t stood out for their empathy didn’t sustain much change before and after the task.

To understand the neural mechanisms at play here, the researchers monitored the participants’ brain activities through fMRI (functional magnetic resonance imaging). Turns out, cortisol, the “stress hormone,” may have been at the heart of it. For highly empathetic people, the hormone altered brain activity in the right dorsolateral prefrontal cortex of the brain. This region is associated with social decision-making — allowing the researchers to understand the neurocognitive impact of stress on altruism.

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However, given that cortisol didn’t have quite the same impact on people deemed not-so-empathetic, makes one wonder if the brain process is just one of the many reasons why stress reduces altruism in people. While there are not many studies attempting to investigate the neural mechanisms behind this, experts have often explored the cognitive processes that might make stress diminish kindness.

“Stress spills into our personal lives in many ways, affecting the quality of our close relationships… When people are stressed, they become more withdrawn and distracted, and less affectionate,” Amie Gordon, a social psychologist at the University of Michigan, had written in Psychology Today.

Researchers involved in a 2015 study reasoned that uncertainty — a feeling stress is often associated with — might be at the heart of making people more selfish. “While anger makes us certain in our righteous indignation, anxiety, and surprise make us unsure of what’s going on and what will happen next. And when we feel uncertain, we tend to fall back on what we know to be true — namely, our own perspectives and feelings,” as one report on the findings reads.

Narrating the time she was about to miss a flight for the first time in her life, Kira Newman wrote: “My anxiety surged at the sight of a long security line, but luckily an airport official ushered me to the front. I didn’t care how the waiting passengers felt about my preferential treatment, and I don’t remember much about the people I encountered during that nerve-wracking afternoon. I was thinking only about my goal: to get home… In short, my empathy for others plummeted as my anxiety mounted.” At a juncture when Newman was uncertain whether she would make it to the flight, she focused entirely on trying to achieve that — and eliminate that uncertainty, in the process.

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Understanding how being stressed affects the way we treat others may perhaps prevent people from deeming one as unkind based solely on an isolated incident of selfishness. At the same time, it may help us — at least cognitively — be more conscious of the treatment we mete out to those we love when we’re stressed, and try to keep a check on it.

Further, as an article from 2015 states: “…it makes intuitive sense that a stressed-out, anxious, uncertain society might be a less empathic and caring one. But it helps to have scientific evidence to bolster the case for public and workplace policies that might make our lives less stressful — and thus, we hope, more compassionate.”

Not only that, studies like the present one also force us to reckon with the idea that not everyone even has the privilege to be altruistic — no matter how empathetic they may be. This is especially true when people are stressed by work that never ceases to end, worried about paying their bills, and generally, are combating heat-induced stress while existing in a global warming-ravaged world without being able to afford air conditions.