Early-life events linked to lung health in young adulthood

Chronic bronchitis and chronic obstructive pulmonary disease (COPD), with the hallmark features phlegm and irreversible airflow limitation, respectively, are lung diseases known to affect adults with a history of long-term smoking.

"To our surprise, we found the prevalence of chronic bronchitis and irreversible airflow limitation to be rather high (5.5% and 2.0%, respectively), considering the young age of the study participants." says senior author Erik Melen, professor and paediatrician , Department of Clinical Science and Education, Karolinska Institutet, Sodersjukhuset.

"Those diseases are usually diagnosed in patients older than 50 years of age," comments further co-author Anders Linden, professor and pulmonologist, Institute of Environmental Medicine.

In the present studies, the researchers used data from birth up to age 24 years from the follow-up of the Swedish population-based birth cohort BAMSE (Swedish abbreviation for Child (Barn), Allergy, Milieu, Stockholm, Epidemiological), which includes 4,089 participants from the Stockholm area recruited 1994-96.

Analyses performed by PhD student Gang Wang showed that smoking as well as early-life air pollution exposures and childhood asthma are risk factors for chronic bronchitis, whereas breast-feeding was identified as a protective factor.

In addition, the early-life risk factors for development of irreversible airflow limitation were recurrent lung infections, asthma, and exposure to air pollution.

"The levels of air pollutants in the current study mainly reflect local emissions from road traffic, which implies that this preventable risk factor may play an important role in the development of chronic lung disease in young adults." says professor Erik Melen.

Given that air pollution levels in Stockholm are comparatively low by international standards, this makes the current findings very important in a global context. And despite the young participants' age, active smoking was linked to chronic bronchitis, which underlines the negative health effects from even a limited period of exposure to tobacco smoke.

"In conclusion, our two novel studies demonstrate that chronic bronchitis and irreversible airflow limitation do exist in young adults and emphasize the importance of early-life events for maintaining lung health during adulthood. The take home-message is: If you want to prevent disease, early prevention is the key to success."

The study was financially supported by the European Research Council (TRIBAL, 757919), the Swedish Research Council, the Swedish Heart-Lung Foundation, Region Stockholm and the China Scholarship Council.