Washington DC, May 4: A recent study states that children who develop multiple allergies tend to suffer from chronic inflammatory diseases and psychiatric disorders in their adulthood. The study was published in the journal BMC Medicine. The human immune system forms during childhood. The "hygiene hypothesis" provides a widely regarded perspective on this.

It suggests that improved hygiene, changes in agriculture and urbanisation have caused our immune systems to come in contact with certain microbes. It is presumed that these developments have adversely resulted in an increased incidence of chronic inflammatory diseases, allergies and mental disorders such as depression. Taking the hygiene hypothesis as a starting point, an interdisciplinary group of researchers at the Universities of Zurich and Lausanne analysed epidemiological data from a cohort of almost 5,000 people who were born in the mid-20th century. Can Your Child Be Allergic to Vaccines? You Must Know These 5 Things about Vaccine Allergies.

They focussed on the co-incidence of allergies, viral and bacterial diseases, and psychosocial stress in childhood. On the basis of early morbidity patterns, the scientists identified five different groups of people that they characterised by biomarkers (white blood cell counts, inflammatory markers) and, in a further step, by their association patterns with chronic inflammatory diseases and psychiatric disorders during adulthood.

One in five people has a very resistant immune system.The main group, which comprised almost 60 per cent of the total cohort analysed, possessed an ordinary, "neutral" immune system. Their disease burden during childhood was comparatively low. Childhood disease burden was even lower for the second-largest group comprising more than 20 per cent of the total cohort: that group exhibited an especially resistant immune system.

Even symptoms of common childhood diseases like measles, mumps or rubella, which were not preventable in the mid-20th century, appeared far less frequently in this group than in the "neutral" group. The "resilient" group is juxtaposed by three smaller groups. The "atopic" group (7 per cent of the total cohort) exhibited incidents of multiple allergic diseases. The roughly same-sized "mixed" group (approximately 9 per cent) was characterised by single allergic disorders such as drug allergies, for example, and by bacterial and rash-inducing childhood diseases like scarlet fever, pertussis or rubella.

The smallest of the five groups (approximately 5 per cent) comprised of people who were traumatised in childhood. They were more susceptible to allergic diseases but responded comparatively resiliently to common childhood viral diseases. A comparative analysis has revealed that the "neutral" and "resilient" groups were larger among people with earlier birth years than they were among individuals with later birth years.

People belonging to the "resilient" group were better protected in adulthood not just against chronic inflammatory diseases, but also against mental disorders. Members of the "atopic" and "mixed" groups, on the other hand, were susceptible to elevated somatic and psychiatric health risks in later age. The "traumatised" group likewise exhibited a greater predisposition to psychiatric illness in adulthood as well as a higher risk of suffering from chronic inflammatory diseases.