Depressive symptoms are common among individuals with asthma and are known to worsen disease outcomes, including symptom control, exacerbation risk, and quality of life. In major depressive disorder, reduced levels of brain-derived neurotrophic factor—a protein involved in neuronal survival and plasticity—have been widely reported, and serum BDNF has been explored as a potential biomarker for depression. However, emerging experimental evidence suggests that BDNF may play a different role in asthma, particularly in airway inflammation and remodeling.
To better understand this relationship, Kazuma Kawamoto from the Department of Molecular and Internal Medicine, Graduate School of Biomedical and Health Sciences, Hiroshima University, Japan, and colleagues conducted a clinical study examining the association between serum BDNF levels, depressive symptoms, and asthma-related clinical factors. Their findings were published in
The Journal of Allergy and Clinical Immunology: In Practice.The study included 140 patients with asthma. Serum BDNF concentrations were measured using enzyme-linked immunosorbent assays, while depressive and anxiety symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS). To capture real-world functional status, daily physical activity was objectively measured with a triaxial accelerometer. The investigators first explored factors associated with serum BDNF levels and then examined clinical variables linked to depressive symptom severity.
The following were the key findings:
- Serum BDNF levels showed a clear positive association with depressive symptoms in patients with asthma.
- Higher BDNF concentrations were independently associated with higher HADS depression scores after adjustment for potential confounding factors.
- Elevated BDNF levels were also linked to greater asthma severity.
- Patients with more severe depressive symptoms exhibited poorer asthma control.
- Higher depression severity was associated with lower levels of daily physical activity.
- The findings suggest a close interaction between biological disease activity, mood symptoms, and functional impairment in asthma.
- The observed relationship between BDNF and depression in asthma contrasts with major depressive disorder, where lower BDNF levels are typically associated with more severe depression.
The authors note that these results support the idea that depressive symptoms in asthma may arise through mechanisms distinct from those driving primary mood disorders. Rather than reflecting neurotrophic deficiency, elevated BDNF in asthma-related depression may be linked to chronic inflammation, airway pathology, or sustained physiological stress.
Clinically, the findings suggest that depression in asthma should not simply be viewed as comorbid major depression. Instead, it may represent a disease-specific phenotype that requires tailored assessment and management. Understanding the unique biological pathways involved could help refine screening strategies and guide more personalized interventions for patients with asthma experiencing depressive symptoms.
Reference:
Kawamoto K, Iwamoto H, Hirano T, Amano Y, Fukatsu-Chikumoto A, Yamane M, Otani T, Higaki N, Isobe T, Yokoyama A, Matsunaga K, Hattori N. Brain-Derived Neurotrophic Factor Levels Are Associated With Depressive Symptoms in Patients With Asthma. J Allergy Clin Immunol Pract. 2025 Nov 11:S2213-2198(25)01032-3. doi: 10.1016/j.jaip.2025.11.001. Epub ahead of print. PMID: 41232711.
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