Evolution of Asthma: More Than Just a Lung Disease
Most people still think of asthma as just a lung disease. This makes sense considering the telltale sign of asthma is difficulty breathing. A rising slew of evidence, however, now has researchers believing asthma is more than just a lung disease, that it is a syndrome affecting many bodily systems. Here’s a list of systems researchers now think are linked to asthma.
Immune System. First and foremost, asthma is now considered an autoimmune disorder. This means the immune systems in those susceptible to developing asthma (those with the asthma gene) develop an abnormal response whereby it treats inhaled substances innocuous (harmless) to most people (dust mites for example) as enemies (like harmful bacteria). The immune system then sets off a series of chemical reactions aimed at killing and getting rid of the enemy. This response involves the release of inflammatory markers that cause inflammation (swelling) of cells lining the respiratory system. This is what causes both allergies and asthma.
Respiratory System. Inflammatory markers may cause inflammation of any tissues lining the respiratory tract, from the sinuses and nose to the smallest air passages.
- Allergies. This leads to allergies and allergy symptoms like red and itchy eyes, stuffy and runny nose, sneezing and coughing. This may also increase your risk of developing sinusitis (sinus infections) or conjunctivitis (pink eye) and even eczema (itchy skin).
- Asthma. Continuous exposure to asthma triggers (like dust mites) may cause airways to become chronically inflamed, making them hypersensitive. Subsequent exposure to that trigger causes this inflammation to worsen, leading to asthma symptoms like wheezing and shortness of breath.
Intestinal Tract. Researchers have observed a link between the esophagus, the stomach, and asthma. Stomach contents may work their way back up the esophagus enter the lungs. This is called aspiration, or gastrointestinal reflux (GERD). The amount of stomach contents inhaled may be so minute you don’t even realize it’s happening. Researchers don’t yet know whether this is due to asthma itself or the medicines used to treat it. This may explain why you’ll find many asthmatics on anti-reflux medicines.
Nervous System. The great 19th Century physician, Henry Hyde Salter, was convinced asthma was a disease of the mind, causing physicians to treat asthma with anti anxiety remedies. This theory was disproved in the 1950s, although some physicians continued to treat asthma this way until the 1980s. Now we know that while anxiety doesn’t cause asthma, it may act as an asthma trigger. That said, researchers have observed a link between asthma, allergies and anxiety, and one theory is that inflammatory markers may also lead to anxiety. And, that aside, allergy and asthma attacks may cause quite a bit of anxiety in and of themselves.
Cardiovascular Systems. A study published in 2015 showed a link between asthma and chronic headaches, where asthmatics with occasional headaches were twice as likely to develop chronic migraine compared to individuals without asthma. A separate study showed a link between asthma and heart disease, where asthmatics were twice as likely to be diagnosed with high blood pressure and high cholesterol than individuals without asthma. The fact that many asthmatics lead sedentary lives, or may be overweight, may explain these findings. Another theory is that inflammatory markers are once again the culprit.
- Sleep. Anywhere from 50 to 75 percent of asthmatics say they have a hard time sleeping at night. This may be due to asthma attacks being more likely to occur at night, although even asthmatics with good asthma control report insomnia. The reason remains unknown, although some suspect that asthma medicines are the culprit. Of course, it’s also possible inflammatory markers are guilty here too.
- Adipose Tissue. Various studies have linked obesity with asthma. This may be due to asthmatics being more sedentary, or it may be that fat tissue releases inflammatory markers. High fat foods have also been linked to asthma, and one theory is that their bodies treat saturated fat as an enemy, thus setting off the immune response that increases inflammatory markers inside the body.
What to make of all this. Okay, so you could say this new evidence as painting a more grim picture of asthma. But this shouldn’t be the case. For years asthmatics have suffered from anxiety, reflux, insomnia, and high blood pressure, and these things have gone unrecognized and untreated. By learning that asthma is more of a syndrome than just a lung disease, doctors now understand they must screen their asthma patients for these other conditions that may occur in conjunction with asthma. This should help all asthmatics live better with it.
John Bottrell is a registered Respiratory Therapist. He wrote for HealthCentral as a health professional for Asthma and Chronic Obstructive Pulmonary Disease (COPD).