Evidence shows asthma treats women worse than men, and researchers believe this may be due to hormones responsible for the menstrual cycle, pregnancy, and menopause. This has lead them to identify a new subtype of asthma called premenstrual or premenopausal asthma. So, what is this, and what does it mean for women with asthma
First, check out these statistics from the American Lung Association.
- Boys are more likely to have asthma than girls until puberty, at which time women are more likely to have it than men until menopause. Among children under 18, boys were 14 percent more likely to have it than girls. Among adults 18 and over, females were 62 percent more likely to have asthma than men.
- According to the American Lung Association, in 2011, women were 14 percent more likely to be diagnosed with asthma than men. In the same year, 10.8 million males had asthma compared with 15.1 million females.
- Women also have more asthma attacks than men. In 2011, 5.1 million males had asthma attacks, while 8 million females had asthma attacks. This difference has been significant since 1999. Of the 3,388 people who died of asthma in 2009, 64 percent of these deaths occurred in women.
What is premenopausal asthma? This is an asthma subtype that affects women during their reproductive years, or from puberty to menopause. Studies show about 40 percent of premenstrual women with asthma tend to have increasingly inflamed airways during or immediately following menstrual periods, making their airways hypersensitive to asthma triggers. Symptoms include increased coughing, wheezing, and shortness of breath. About 50 percent of hospital admissions for asthma in premenstrual women occurs during these times.
So, why does asthma impact women worse than men? While the exact mechanisms are unknown, a common hypothesis is that three hormones may have an impact on the immune response responsible for asthma.
1. Testosterone. It’s often referred to as the male sex hormone that circulates in the bloodstream. It binds with receptors on targeted cells, and is responsible for the development of male sex organs. A rise in testosterone levels during adolescence is responsible for boys becoming men. It plays a role in the development of sperm cells, abdominal fat, and hair loss.
Levels decline gradually, about 1 percent per year, starting in the mid 30s, thereby remaining relatively stable throughout one’s lifetime. It’s also produced in women, although at significantly lower levels.
Researchers believe testosterone suppresses the immune response responsible for asthma and allergies. This may explain why asthma in boys is more likely to go into remission during teenage years than girls. This may also explain why women seem to be at greater risk of more severe asthma attacks than men. To get a better understanding of the impact of testosterone on asthma you can read our post “Links Between Asthma and Testosterone.”
2. Estrogen. This refers to female sex hormones: estrone, estradiol, and estriol. It circulates in the bloodstream and binds with receptors on targeted cells, affecting the breasts, uterus, brain, bone, liver, heart, lungs, and other organs. Unlike testosterone levels in men, which are relatively stable, estrogen levels rise and fall during the menstrual cycle during reproductive years (before menopause). They rise to help prepare the uterus and breasts for possible fertilization, and then fall sharply if the egg is not fertilized.
Researchers believe estrogen receptors are also present on key cells responsible for the asthma and allergic responses. So they suspect that it is for this reason women are more prone to developing asthma after puberty than their male counterparts. This may also explain why asthma symptoms are more likely during ovulation, menstruation and pregnancy. This may also help explain why women have it worse than men.
Making matters worse, studies also show that postmenopausal women who receive estrogen replacement therapy also have an increased incidence of asthma.
3. Progesterone. This is a hormone that rises along with estrogen to prepare the body for possible fertilization during reproductive years. Like estrogen, progesterone levels drop sharply if the egg is not fertilized. Researchers believe progesterone acts as an airway dilator. So they suspect the sudden drop in progesterone following menstruation may create a withdrawal period where the airways of women may become increasingly inflamed and sensitive to asthma triggers. This may also explain worsening asthma symptoms immediately after menstruation.
There are other theories too. Similar to severe asthmatics, premenopausal asthmatics may develop chronic airway changes. For instance, some research shows “impaired or altered” beta 2 adrenergic receptor “function and regulation” in females with asthma.” These are receptors that, when stimulated, cause airways to constrict, thus causing asthma symptoms.
What does this mean? It means that researchers are now working overtime to learn more about the impact of asthma on women. They know most female asthmatics respond well to traditional asthma medicines, although some continue to struggle with asthma control. Ideally, this will lead to improved treatment options and asthma guidelines tailored specifically for premenopausal asthmatics. The ultimate goal here is better asthma control for women.
References and further reading:
What are Asthma Subtypes and Groups?
Links Between Asthma and Testosterone
What Are Your Asthma Triggers?
ALI: Trends in Asthma Morbidity and Mortality
NCBI: Premenstrual asthma: epidemiology, pathogenesis and treatment
NCBI: Estrogen Effects in Allergy and Asthma
Healthy Women: What is estrogen?
U.S. News: The Pill May Reduce Asthma Symptoms
PubMed: Menopausal Asthma: A New Biological Phenotype
Emergency Asthma, 1999, Barry E. Brenner, page 147