In neuroscience studies, loneliness is described as a condition that alters the functioning of the body. It changes stress levels, alters inflammatory processes, and affects the ability to recover after a stroke or heart attack. This is where the research conducted by neuroscientist Ben Rein, and recounted in a recent interview with the Guardian, begins.
Rein has been working for years on a topic that seems less and less marginal today: what happens to the brain when relationships thinn out. The answers emerging from the scientific literature are consistent and, in some ways, difficult to ignore. Social isolation produces measurable effects.
The stress that stays on
Some of the clearest evidence comes from animal studies. In experiments in which groups of mice are induced to suffer identical strokes, specimens living in isolation show worse outcomes: more brain damage, less ability to recover, higher mortality. The difference does not depend on the type of injury, but on the social context.
According to Rein, isolation activates a profound stress response, linked to an ancient evolutionary mechanism. Being alone, for a social species, is a danger signal. The body reacts by releasing cortisol, preparing for a threat. The problem arises when this condition is prolonged. Stress becomes chronic, and cortisol loses its ability to modulate inflammation, which tends to accumulate.
The effects on humans
In humans, the picture is no different. A meta-analysis published in PLoS Medicine showed that weak social relationships increase mortality risk by about 50 percent, an impact comparable to that of known risk factors such as smoking. Other studies indicate that people living alone after a heart attack have higher odds of death over the next three years than those living with others.
In the case of stroke, emotional support plays a relevant role. Longitudinal research has shown that patients who report high levels of emotional support show more marked functional improvements over time, even starting from worse initial conditions.
The role of the relationship
One of the keys proposed by Rein concerns oxytocin. During social interactions, the brain releases this hormone, which has anti-inflammatory effects, reduces stress and promotes healing processes. It’s not just about perceived well-being.
A study published in the Journal of Clinical Oncology showed that married people have higher cancer survival rates. The stable relationship, in this context, is not an affective variable, but a biological one.
Oxytocin also activates dopamine and serotonin, substances involved in motivation and mood regulation. It is a circuit that makes the relationship rewarding, but more importantly, functional for survival.
Why do we isolate ourselves
An open question remains: if the relationship is so good for us, why do we tend to avoid it? Psychological research shows that humans are inaccurate in predicting how much they will like a social interaction. They underestimate their own relationship skills and how much others will like them, a phenomenon known as the “liking gap.”
Added to this is an ancient caution related to the need in prehistoric societies not to compromise the bond with one’s family group. Today that caution often translates into social anxiety and withdrawal.
The limit of digital
Online interactions have expanded opportunities for contact, but they do not fully activate the brain systems of sociality. Basic signals such as body language, continuous eye contact, and micro-expressions are missing. According to Rein, this deficiency makes it more difficult to interpret others’ emotions and contributes to increased conflict and hostility in digital spaces.
It is not a detail that some studies have shown that emoji also activate neural responses similar to those of real human faces. It is a sign of how much the brain looks for social references, even in a reduced form.
An issue that affects everyone
Reducing loneliness to an individual issue risks being misleading. Neuroscientific evidence shows that isolation affects health and resilience, with effects that are also reflected collectively.
The human brain, these studies suggest, is not designed to function in the absence of relationships. It changes trim, chemistry, stress response. To take these data seriously is to recognize that connectedness is a condition that holds health, community, and social resilience together.
