Contact with animals helps people to prevent stress

Study: Rural residents with contact with livestock can handle stressful situations better

Despite technical progress, the working pressure of many citizens is increasing more and more. Those who are constantly stressed are also more susceptible to diseases. Countryside residents are obviously clearly in the advantage here. As has now been shown in a study, people who have grown up in the countryside and have close contact with livestock can cope better with stress situations.

Healthy country life

Increasing work pressure and stress endanger health. Relaxation and rest are important for humans. To switch off you go best to nature or the countryside. Because most people can recover the best there. But what makes rural life so healthy and restful? The village tranquility, the fresh air or the intact neighborhood? Scientists at the University of Ulm have a completely different answer: rural residents with close contact to livestock can manage stress situations immunologically much better than city dwellers who grew up without pets. They get help from the "old friends" among the microbes.

According to a new study, people who grew up on a farm with livestock can handle psychosocial stress better than city dwellers who grew up without pets. (Image: JackF / fotolia.com)

Subjects more and more pressured

"This refers to environmental bacteria with which humans have been living together peacefully for millennia, and which are having a hard time in the big city today," explains Professor Stefan Reber in a statement from the university.

The head of the Department of Molecular Psychosomatic Medicine at Ulm University Hospital for Psychosomatic Medicine and Psychotherapy, together with colleagues from the University Hospital Ulm and researchers from Erlangen, London and Boulder (Colorado) found that men who spent the first 15 years of life on a farm with livestock grown up, psychosocial stress can handle better than men who spent the first 15 years of life in a large city with over 100,000 inhabitants and no pets.

For their study, recently published in the journal "PNAS", the researchers subjected a total of 40 healthy male volunteers to a stress test and, in addition, collected stress hormones and immunological parameters.

The subjects were "stressed out" in a standardized laboratory experiment with the so-called "Trier Social Stress Test" (TSST).

In the process, the test subjects are exposed to a fake job application situation and put under more and more pressure. In between, you have to solve mental arithmetic problems and start over again in case of errors.

Before and after the test, scientists took blood and saliva samples to detect certain immune cells, such as peripheral blood mononuclear cells (PBMCs), or to record stress parameters such as cortisol.

The immune system of the rural inhabitants was less provoked by the stress

It emerged that the "rural residents" in the test on the one hand showed higher stress levels than the "big city dwellers"; both the basal levels of stress hormone were higher and the subjective stress perception questioned in the questionnaire.

On the other hand, the immune system of the "rural dwellers" was not provoked as strongly as a reaction of the "city dwellers" who had no contact with animals in their childhood.

Thus, not only was the stress-induced increase in PBMC larger for those subjects who grew up in the big city without animals, but also the levels for the inflammatory marker interleukin 6 remained longer elevated than in the comparison group.

And another clear indication that the immune system of the "rural dwellers" cope better with stress, the scientists found.

For this purpose, the isolated peripheral blood mononuclear cells were examined for the release of the anti-inflammatory agent Interleukin 10.

The result: after the stress test, the release of this anti-inflammatory substance was significantly reduced in the non-urban population, but not in the lore-oriented countries.

Chronic inflammatory reactions

Excessive immune responses are a health problem because they often lead to chronic inflammatory reactions.

"Such processes play a role, for example, in the development of asthma and allergic diseases, but also increase the risk of mental illnesses such as depression and post-traumatic stress disorder," explains Ulrich Psychoneuroimmunologe Stefan Reber.

It has long been known that susceptibility to asthma and allergies, as well as mental illness in people who live in the city, is above average, or protects the farm life from allergies.

With the global trend towards urbanization - more and more people are moving from the countryside to the major cities - this finding is even more explosive.

The fact that the lack of contact with certain bacteria plays a key role, as the so-called "missing microbes" hypothesis implies, has been suspected in research for a few years.

"Vaccination" with environmental bacteria

In an earlier experiment with mice, a research team led by Professor Reber has already shown that the animals' resilience to stress can be improved by "vaccination" with such well-known environmental bacteria.

It would be nice, of course, if the results could be transferred from the mouse to humans. In the future, such a vaccine could possibly also function in human risk groups.

Whether the city may also have early contact with pets, the scientists want to find out in a follow-up study. (Ad)