Children’s Asthma, Adult’s Asthma – One and the same disease?
300 million people suffer from asthma. It is the most prevalent chronic airway disease worldwide. Although many clinical studies have been performed in the past, there are still several open questions. For example, it remains elusive why only 3-5% of children with early symptoms develop persistent asthma. What happens during adolescence? And why are there cases in which asthma appears in adulthood? Four medical doctors of the German Center for Lung Research (DZL) summarized the state of knowledge in a review article published in the journal Lancet Respiratory Medicine. They recommend concerted research of pediatric and adult pulmonologists.
Asthma is a complex disease. Children suffer from so-called wheezing, a characteristic breath sound due to constriction of the airways. Later, this can evolve into more severe symptoms like coughing attacks or dyspnea. Duration and severity of attacks differ from patient to patient. The trigger factors also differ: Allergic asthma is provoked by contact with the respective allergens. In other asthmatics, acute symptoms are triggered by viral infections or cigarette smoke. However, they all have a chronic airway inflammation in common.
Asthma has been studied in several trials. In children, epidemiological studies have been performed in order to investigate the development of symptoms. Surprisingly, it has been found that just 3-5% of all children with wheezing or early asthma symptoms develop an asthma that persists into adulthood. In another group, symptoms vanish, but reappear in adult age. Moreover, there are patients which experience their first asthma attack only as adults. These “adult asthmatics” suffer from the most severe symptoms.
The authors of the article identified a knowledge gap, a “black box”, in the time period of adolescence. This is due to the fact that many patients drop out of studies during this age: In some of them symptoms suddenly get better and they stop seeing their physician. Others change their place of residence – due to occupational reasons, e.g. – and cannot participate in local studies anymore.
A wide range of methods is used in studies with adults: Besides clinical data, biomaterials like sputum and small biopsies can be collected. The latter is not possible in children. Studies with adults have the disadvantage that the participants’ detailed medical history is often missing.
What is known about the causes of asthma? There are a number of risk factors for asthma: Genetic, epigenetic and environmental influences play a role. People who are already suffering from atopy or allergy bear a higher risk of developing asthma. One of the most important environmental triggers is cigarette smoking. This may already have consequences for unborn babies of smoking mothers. It is known that a remission of symptoms during adolescence occurs mostly in boys. The biological background for this is not clear. In general, researchers assume that the underlying airway inflammation is going on, although typical symptoms arise less often or not at all anymore.
The authors of the article advocate that standardized molecular approaches for studies in children as well as in adults should be utilized in order to answer open questions on different courses and causes of the disease. “In this context, DZL aims at studying patients regularly on a long time scale – from infancy to adulthood”, says Dr. Thomas Bahmer of LungenClinic Grosshansdorf. Therefore, so-called transition clinics are installed in order to follow the transition from adolescence to adulthood in detail. “If we knew all different courses of asthma and the molecular causes, we could predict, which therapy is best for a specific patient – or we could tell him that he doesn’t need any therapy at all, because the symptoms are only of temporary nature”, outlines Dr. Oliver Fuchs (Ludwig-Maximilians-Universität Munich) a future treatment strategy. Whether asthma is one uniform disease or a number of different disease patterns is under discussion at present. It is most probable that doctors will be able to treat patients much better and in a more personalized fashion, when different courses of the disease are known more exactly.
The recently published review article is the outcome of collaboration between the DZL Sites ARCN and CPC-M. Dr. Oliver Fuchs and Prof. Dr. Erika von Mutius are pediatric allergists at the Children’s Hospital of the Ludwig-Maximilians-Universität in Munich. In the framework of the DZL, they are working on the Children’s Asthma Registry (KIRA). Dr. Thomas Bahmer and Prof. Dr. Klaus F. Rabe are physicians of the Department of Pneumology at LungenClinic Grosshansdorf and organize the Adult’s Asthma Registry (ERA). Both studies are performed with further DZL partners.
Further information: Fuchs O*, Bahmer* T, Rabe KF, von Mutius E (2017) Asthma transition from childhood into adulthood. Lancet Respir Med 5: 224-234 *shared first authors