Traumatized children and children who develop multiple allergies tend to be more susceptible to chronic inflammatory and psychiatric conditions in adult life. Researchers from the Universities of Zurich and Lausanne show this in a study in which they identify five groups of early programming of the immune system.
The immune system is shaped in childhood: the so-called hygiene hypothesis provides a very considered perspective. He says that better hygiene, changes in agriculture and urbanization have led our immune system to come in contact with some microbes less often or later in life. The negative consequences of this development are the increase in chronic inflammatory diseases, allergies and mental illnesses, such as depression.
Based on the hygiene hypothesis, an interdisciplinary group of researchers from the Universities of Zurich and Lausanne investigated epidemiological data from a cohort of just under 5,000 people from the mid-twentieth century. She focused on the coincidence of allergies, viral and bacterial diseases, as well as psychosocial stress in childhood. From the earliest disease patterns, scientists identified five distinct groups, which they characterized using biological markers (white blood cells, inflammatory markers) and, in a second step, associated with chronic inflammatory diseases and mental disorders in adult life.
One in five have a very resistant immune system
The main group, which included almost 60% of the individuals studied, had a discrete and "neutral" immune system. His burden of childhood illness was comparatively low. This was even more surprising for the second largest group, with more than 20% of the population: it showed a resilient and particularly resilient immune system. Even typical symptoms and unavoidable diseases of childhood, such as measles, mumps, or rubella, manifested significantly less in this group than in the neutral group.
The resilient group faces three smaller groups: the "atopic" group (7%) had several allergic diseases. The nearly equal mixed group (about 9%) was characterized by individual allergic diseases – such as drug allergies – as well as infantile diseases related to rash such as scarlet fever, whooping cough or rubella. The lowest of the five groups (about 5%) included people traumatized during childhood. They were more susceptible to allergic diseases, but were relatively resilient in viral diseases typical of childhood.
Hygiene hypothesis thought ahead
Comparative analyzes have shown that neutral and resilient groups are more often represented in older groups than younger ones. It was the exact opposite of the atopic group: it increased in younger years. "Our study confirms the hypothesis of hygiene," says Ajdacic-Gross, "but at the same time it goes beyond them."
Differences between groups also manifest themselves in terms of later health. People belonging to the resilient group were better protected in adulthood, not only from chronic inflammatory diseases, but also from mental illness. On the other hand, those who belonged to the atopic or mixed group were subsequently exposed to an increased risk of disease – both in the somatic and in the mental area. The traumatized group also showed greater susceptibility to mental illness in adulthood and, however, only in women, a higher risk of chronic inflammatory disease.