Risk factors for the development of asthma in adults: adiposity, metabolic syndrome, mental distress and their interplay

Abstract

Asthma is a chronic inflammatory disorder of the airways that involves a wide variety of cells and cellular elements. Symptoms of asthma include temporary episodes of breathlessness, wheezing, coughing, and tightness of the chest, which may occur more frequently at night or in the early morning. While there is a growing understanding of the inflammatory processes and the onset of symptoms in people with asthma, the causes of asthma development are not well understood, particularly in adults.This thesis used information from the large population-based Nord-Trøndelag Health Study to conduct a series of prospective observational studies to investigate potential risk factors for the development of asthma in adults and their interplay. We studied several potential risk factors for adult asthma by investigating the associations of 1) general and abdominal obesity with incident asthma, 2) metabolic syndrome and its components with incident asthma, 3) anxiety or depression symptoms with incident asthma, 4) anxiety or depression symptoms with weight change and incident obesity, and 5) the joint associations of anxiety or depression symptoms and obesity with incident asthma.We found modest positive associations between general and abdominal obesity, metabolic syndrome and anxiety or depression symptoms with incident asthma. Our study also suggested that anxiety or depression symptoms were positively associated with weight change and incident obesity in both men and women. Additionally, we found that having anxiety or depression symptoms together with obesity was positively associated with incident asthma, and this joint association was substantially stronger than the sum of either factor alone. The findings of these  studies warrant further research to address the underlying mechanisms of these associations. Such research could improve the understanding of the etiology of asthma and thereby assist ongoing efforts to prevent asthma.