Asthma and Other Lung Diseases
Many people with asthma have other lung diseases as well. It is common for asthma to overlap with COPD (chronic obstructive pulmonary disease) in older adults. One study looked at people ages 50 years and older with obstructive lung disease. The results showed that up to half have been diagnosed with two or more lung diseases.1
More and more research is showing that childhood health has long-term effects on the lungs. These findings may partially explain the link between asthma and other lung diseases.
How is early childhood health linked with asthma?
The lungs grow and develop during childhood. Babies born early have immature lungs. They are more likely to wheeze and cough during childhood.2 Some children outgrow these symptoms, while others continue to have breathing problems into early adulthood.3
Age three years seems to be an important landmark for lung health. Children who had pneumonia before they were three years old have lower lung function up to age 26 years.4 Early pneumonia is also linked with having twice the risk of asthma up to age 29, compared with people who did not have pneumonia. Having asthma before age three years affects lung function growth, whereas asthma that starts later does not.5
Early lung problems may put children on a path to abnormal lung development.3 But there are still a number of questions. Does early damage to the airways mean that the airways do not grow normally? Or does being born with lower lung function make children more likely to have lifelong lung problems? Studies have not provided the answers yet.
How are asthma and COPD linked?
Adults with asthma are more likely to develop COPD than adults without asthma.3 One 20-year study showed that people with asthma were:6
- 10 times more likely have symptoms of chronic bronchitis
- 17 times more likely be diagnosed with emphysema
- 5 times more likely to have COPD
In fact, features of asthma and COPD start to overlap over time.6
- Decline in lung function is typical for COPD, but also happens in some people with asthma.
- Airway sensitivity (hyperresponsiveness) is typical of asthma, but some people with COPD have sensitive airways.
- One hallmark of asthma is that the airway obstruction can be reverse with medication. However, reversibility can decline over time for people with moderate or severe asthma.
It can be hard to get the diagnosis right, especially in older adults. Overlap between the two conditions is so common, that the term “Asthma-COPD Overlap Syndrome” is sometimes used.7
How are asthma and bronchiectasis linked?
People with bronchiectasis have permanently widened airways. Long-term inflammation of the airways causes bronchiectasis. Some people are born with it, others develop it because of recurring infections.8
About 2% to 3% of people with asthma also have bronchiectasis.9,10 People with both conditions are more likely to have severe asthma and more frequent asthma attacks than people with asthma alone. 9,10 Consequently, they use more steroids and have more visits to the emergency room.
How are asthma and lung cancer linked?
There are no studies that clearly link asthma and lung cancer. One review paper showed that there might be a statistically increased risk.11 However, the authors looked closely at the data and concluded that the link could be explained by smoking or misdiagnosis of early cancer symptoms.
A large case-control study of people in Europe and Canada show that people with asthma actually had less risk of lung cancer.12 The authors explained that people with asthma may avoid things that increase the risk of lung cancer, such as smoking or certain types of work.