[The natural history of asthma]

Asthma is a chronic inflammatory disease of airways with a multifactorial pathogenesis. Both genetic and environmental factors contribute to the development of the disease which can vary in the same patient through time. Due to its complexity, natural history of asthma is poorly well-known. Generally, in the history of asthma three periods of life are taken into consideration: early childhood, adolescence and adult life. It has been demonstrated that less than one third of children who are affected by wheezing in early childhood develop a true asthma afterwards. Usually in these subjects who are male and atopic, viruses and subsequently allergens represent the most important factors responsible for the development of asthma. During adolescence airborne allergens represent the main cause of the disease: mites in infancy and pollens in late childhood. The incidence of asthma during adolescence is growing according to recent studies, and even if the symptomatology of asthma improves through time, about two thirds of patients remain asthmatic in their adult life. As regards adults etiology, it is less known, women are more frequently affected than men and the prognosis is generally poorer. Several factors negatively influence the course of asthma such as age, smoking, the severity of the disease during infancy, the persistence of functional obstructive alterations and the increased aspecific bronchial reactivity. Adequate therapy is crucially important to cope with these factors and can change the course of the disease.