Airway Tree Variations - Another Clue to COPD Risk
COPD is the fourth leading cause of death in the U.S. and affects 16 million people. Additional millions have the disease, but have not yet been officially diagnosed. So, a big focus for COPD research is to better understand the causes and risk factors of COPD. This will hopefully help us to find potential ways to prevent COPD. It will also help us learn how best to manage and treat the disease.
Tobacco smoke is the leading risk factor for COPD, although there are other known risk factors as well. However, not all smokers develop COPD, and many non-smokers do. Experts have not fully understood why until recently.
I previously reported on two studies that suggest poor lung function during childhood may increase risk of COPD later in life. In addition, the study I'm profiling in this post reports more clues related to genetic variations in lung anatomy. These variations may help explain why some people are more at risk for COPD than others, regardless of smoking history.
Details of the study
This study was funded by the National Heart, Lung and Blood Institute (NHLBI for short), which is part of the National Institutes of Health. The study was reported in the journal Proceedings of the National Academy of Sciences in January 2018.
In this study, researchers found that branches in the central airways were different in one quarter (25%) of the population studied. These branches are believed to be formed early in life.
Furthermore, people who had this variation in the central airway branching were also more likely to have COPD. This was true whether they smoked or not. Another variation that was associated with COPD appeared only in smokers.
In the past, experts believed that being exposed to tobacco smoke or air pollution over a long period of time sped up the decline in lung function typical of COPD. But this study and other recent research suggests that older adults with COPD often had problems with poor lung function early in life. Then, as they aged, the normal changes in lung function resulted in COPD, because they started with weaker lungs. It's a subtle difference, but may help explain why some people are more at risk for COPD than others.
How to know if you have these airway branch variations
So, is there a test for this? And if so, would we be able to screen people for the risk of COPD and then do something to prevent or delay it? Well, that is certainly the hope that comes out of discoveries like this!
Unfortunately, we are not quite there yet. Low-dose screening lung CT scans can detect these airway anomalies. These scans are currently used for lung cancer screening in older adults who have a recent long history of heavy smoking. However, experts caution that it is too early for widespread adoption as a screening tool.
Until we are sure that there is anything that can be done once you know you have one of these variations, there may be no real value in knowing. More research will be needed before a recommendation for screening comes about.
Future research is planned to investigate in more depth whether a family history of airway tree variations might also be a factor in COPD risk. The study described above found that in the non-smoker group with COPD, there did appear to be a family history of a specific type of variation. Could there be some sort of genetic basis?
Do you live with any sleep disorders (eg. insomnia, RLS, sleep apnea) in addition to COPD?