Older adults are likely more sensitive to the asthma-promoting impact of environmental estrogens than youth, based on new research presented at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2026 Annual Meeting. 

Chronic asthma is more common in older adults and is associated with higher prevalence, morbidity, and mortality than asthma in young individuals, but the effects of environmental estrogen on older adults have not been well studied, senior author Terumi Midoro-Horiuti, MD, PhD, professor of pediatrics at the University of Texas Medical Branch, Galveston, told Medscape Medical News. 

To tease out age-related differences in response to the environmental estrogens that promote asthma, the researchers used a mouse model involving older mice (older than 18 months) and younger mice (aged 6-8 weeks). The mice were exposed to environmental estrogens in the form of bisphenol S in drinking water for 4 weeks and nasal exposure to cat dander extract every other day for 2 weeks, starting 2 weeks after the bisphenol S introduction. They analyzed airway hyperresponsiveness and collected tissue samples at 24 hours after the last nasal exposure to cat dander. 

Leukocyte and Neutrophils Increased 

At the end of the study period, total leukocytes and neutrophils were significantly higher in older mice vs younger mice. Levels of both serum immunoglobulin (Ig)G1 and IgG2a were higher in the older mice vs the younger, and analyses of cytokine levels in bronchoalveolar lavage fluid and lung homogenates are in progress, the researchers wrote. 

Although human studies are needed, the findings suggest that environmental estrogen exposure hits harder in an older population, the researchers concluded. “Further investigation of the mechanism of different responses is ongoing,” they noted.

Airway hyperresponsiveness is significantly increased in older adults with environmental estrogen exposure, but not in younger adults, Midoro-Horiuti told Medscape Medical News. Children and older adults have T helper type 2 dominant immune status; the overactivity of T helper cells may predispose them to develop allergic asthma, she said. 

Although the current study involved animal models, the clinical takeaway is that older adults are more sensitive to environmental estrogen exposure than youth, Midoro-Horiuti said. “Since asthma patients have increased prevalence of other diseases, including cardiovascular and dementia, we need to study the mechanism and prevention of it,” she added. More research is needed with different concentrations and terms of environmental estrogen exposure along with mechanistic and epidemiological studies in humans, she said. 

Potential Impact on Asthma Patients 

The current study helped model mechanisms of asthma in older adults, and understanding age-specific pathways is important given the high burden of asthma-related morbidity in this population, said Arianne K. Baldomero, MD, a pulmonologist and assistant professor of medicine at the University of Minnesota, Minneapolis. 

“If similar mechanisms are confirmed in humans, environmental estrogen exposure could represent a modifiable risk factor for asthma exacerbations in older adults,” Baldomero told Medscape Medical News.

Key limitations of the study include the use of a mouse model, which may not fully translate to humans, said Baldomero, who was not involved in the study. “Additional research is needed to evaluate other environmental estrogens and determine whether they produce similar age-related effects,” she said. Testing potential interventions in animal models, such as strategies to reduce environmental estrogen exposure, will be important to assess whether these approaches improve airway hyperresponsiveness and inflammation, Baldomero noted. 

The study was funded by an intramural grant from the Institute for Human Infection and Immunity at the University of Texas Medical Branch. The researchers had no financial conflicts to disclose. Baldomero had no financial conflicts to disclose.