Lung Development May Explain Why Some Non-Smokers Get COPD and Some Heavy Smokers Don’t

Study says people with small airways relative to the size of their lungs may have lower breathing capacity and, consequently, an increased COPD risk.

According to a new study, people with small airways relative to the size of their lungs may have a lower breathing capacity and, consequently, an increased risk for COPD—even if they don’t smoke or have any other risk factors. The study, funded in part by NHLBI, appeared June 9 in the Journal of the American Medical Association.

Chronic obstructive pulmonary disease (COPD), a debilitating lung condition, often develops as a result of smoking, but researchers have long puzzled over why nearly a third of cases occur in people who never smoked. Now they may finally have an answer—and it may be linked to how lungs develop in certain people. 

“This work, stemming from the careful analysis of lung images of COPD patients, shows that an abnormal lung development may account for a large proportion of COPD risk among older adults,” said Dr. James Kiley, director of NHLBI’s Division of Lung Diseases. “More research is needed to understand what drives this occurrence and to devise possible interventions.”

COPD, the fourth leading cause of death in the United States, causes airflow blockage and breathing-related problems that can severely limit a person’s day-to-day activities. Smoking, asthma or air pollution account for many COPD cases, but up to 30 percent of cases occur in people who never smoked, and only a minority of heavy smokers develop the disease, suggesting that there are other risk factors at play.

Previous research offered a clue about a possible cause, finding that about half of older adults with COPD appeared to have low lung function early in life. 

The findings may also help explain why some lifelong heavy smokers do not develop COPD. People with larger airways relative to lung size may be able to withstand lung damage from smoking and still have enough breathing reserve to prevent them from developing COPD. Still, given the multiple health problems caused by tobacco, smokers should do their best to quit, researchers noted.