Climate and Atopic Dermatitis: 5 Recent Studies to Consider

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Climate can play a role in the manifestation and severity of atopic dermatitis (AD), influencing factors such as skin barrier function, inflammatory responses, and overall disease management. A growing body of research is dedicated to understanding how various climatic elements—temperature, humidity, pollution, and UV exposure—impact AD. In this article, we delve into 5 recent studies studies that explore the intricate relationship between climate and atopic dermatitis.

Weathering the AD Storm in Infants

This retrospective study in Minsk, Belarus aimed to elucidate the relationship between climate and the incidence of early AD in infants. Analyzing 603 children aged 0 to 24 months with clinically diagnosed AD, including 292 with infantile eczema (IE), researchers correlated these cases with mean monthly meteorological data in Minsk. The Mantel-Haenszel method was used to evaluate associations between AD outcomes and meteorological variables, while accounting for potential confounders. Additionally, the study examined the seasons of birth for children diagnosed with AD before 6 months (n=567) and at 12 months (n=350) between 2005 and 2019.¹

The incidence of IE was negatively associated with air temperature (adjusted incidence rate ratio = 0.75; 95% CI 0.59–0.94) and precipitation (0.74; 95% CI 0.58–0.93), but positively associated with atmospheric pressure (1.31; 95% CI 1.04–1.66). IE incidence peaked in spring and was lowest in summer, while AD was less frequent in infants born in spring compared to older children (18.1% vs. 29.4%, P < 0.001). Principal component analysis identified that warm, low-humidity conditions were negatively associated with AD incidence (0.77; 95% CI 0.65–0.92), and rainy, low atmospheric pressure conditions were negatively associated with IE (0.70; 95% CI 0.54–0.90). These findings suggest that cold-humid continental weather may influence early AD incidence, with short-term meteorological factors playing a significant role in IE onset.¹

Rainfall and Air Pollution in Singapore

A time-series study investigated the link between air pollution, weather variability, and the incidence of AD in the tropics, specifically in Singapore. Analyzing 1,440,844 outpatient visits to the National Skin Centre (NSC) from 2009 to 2019, the study employed a distributed lag non-linear model, assuming a negative binomial distribution, to examine short-term associations between AD visits, air quality, and meteorological variability on a weekly basis. Adjustments were made for long-term trends, seasonality, and autocorrelation. The analysis also considered potential modifications by gender and age. Key findings indicated that AD consultation risks were 14% lower at the 10th percentile of PM_2.5 (11.9 µg/m³) and 10% higher at the 90th percentile (24.4 µg/m³) compared to the median value (16.1 µg/m³). Similar patterns were observed for PM10.Higher particulate matter concentrations (both PM_2.5 and PM₁₀) were associated with increased risks of AD consultations, while lower concentrations correlated with reduced risks. Additionally, increased rainfall above median levels was linked to higher consultation risks, with specific thresholds identified in the PM_2.5 and PM₁₀ models. ²

Seasonal Immunologic Shifts With Systemic Therapy

Another study investigated the seasonal immunologic changes in AD patients undergoing dupilumab (Dupixent; Sanofi) therapy compared to those not on dupilumab and a healthy control group. During pollen and non-pollen seasons, researchers measured leukocytes, T lymphocytes, and other immune cell subsets in 21 moderate to severe AD patients without dupilumab, 13 moderate to severe AD patients on dupilumab for at least 18 months, and matched healthy controls. The results showed significant differences in immune cell counts between AD patients and controls, as well as between AD patients with and without dupilumab. Specifically, dupilumab-treated patients had lower CD8+ T lymphocytes, higher monocytes, and lower activated basophils (CD203+). During pollen season, these patients also exhibited higher counts of activated eosinophils (CD16+) and regulatory T cells.³

Beyond the Nose: Pollen and AD

A prospective study in Japan explored the less commonly recognized extrarespiratory symptoms in patients with pollen allergies, traditionally known for causing rhinitis and conjunctivitis. Over a year, 384 patients with pollen allergies documented their weekly symptoms, including skin irritation, via an electronic diary, using visual analog scale (VAS) scores to report symptoms across various organs. The study aimed to correlate seasonal pollen levels with symptom severity, employing a mixed-effects model for repeated measures and k-means cluster analysis. The results indicated that patients sensitized to grass or birch pollen experienced increased VAS scores for headache, gastrointestinal issues, skin symptoms, and fatigue in response to higher seasonal pollen levels. A subgroup of 42 patients with severe pollen allergies was identified, showing significantly higher extrarespiratory symptoms, a greater frequency of comorbid food allergy and atopic dermatitis, elevated IgE sensitization to pollens, and reduced activity and work productivity.⁴

Cleanser Efficacy During Summer Months

A study investigated whether washing with water alone is as effective as using soaps or detergents in children with AD during the summer months. In this evaluator-blinded, pragmatic, randomized, non-inferiority trial, children with controlled AD were enrolled to wash one side of their body with a chosen cleanser (either weakly alkaline soap or acidic detergent) and the other side with water alone for 8 ± 4 weeks. The primary outcome measured was the Eczema Area and Severity Index (EASI) score at the end of the study period. The results from 43 participants showed no significant difference in EASI scores between the water-washed and cleanser-washed sides (0.00 vs. 0.15, p = 0.74), with the confidence interval limits not reaching the non-inferiority margin. Additionally, there were no differences in patient-reported outcomes, steroid ointment use, or skin infection occurrences between the two groups or the types of cleansers used.⁵

The findings indicate that washing with water alone is not inferior to using cleansers for maintaining eczema control in children with AD during the summer, regardless of whether a weakly alkaline soap or an acidic detergent is used. This study suggests that simpler skincare routines using just water could be just as effective as more traditional cleansing methods, potentially offering a cost-effective and accessible option for managing AD in children during warmer seasons. 

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References

1. Belugina I, Yagovdik N, Belugina O, Belugin S. The impact of meteorological factors on the incidence of infantile atopic dermatitis. Int J Dermatol. Published online August 4, 2024. doi:10.1111/ijd.17404
2. Mailepessov D, Ong J, Nasir MZM, et al. Association between exposure to ambient air pollution, meteorological factors and atopic dermatitis consultations in Singapore-a stratified nationwide time-series analysis. Sci Rep. 2024;14(1):10320. Published 2024 May 6. doi:10.1038/s41598-024-60712-4
3. Čelakovská J, Čermáková E, Boudkova P, Krejsek J. The changes of leukocytes and T lymphocytes in atopic dermatitis patients with and without dupilumab therapy and in control group in pollen season compared to out of pollen season. J Dermatolog Treat. 2024;35(1):2318351. doi:10.1080/09546634.2024.2318351
4. Fukutomi Y, Tanaka H, Sekiya K, et al. Uncovering a Severe Patient Group With Pollen-Related Extrarespiratory Allergic Symptoms: A Year-Long Diary Survey in Japan. J Allergy Clin Immunol Pract. 2024;12(6):1495-1506.e7. doi:10.1016/j.jaip.2024.02.011
5. Katoh Y, Natsume O, Yasuoka R, et al. Skin care by washing with water is not inferior to washing with a cleanser in children with atopic dermatitis in remission in summer: WASH study. Allergol Int. 2024;73(3):428-435. doi:10.1016/j.alit.2024.01.007