FRIDAY, Jan. 23, 2026 (HealthDay News) -- Brain-derived neurotrophic factor (BDNF) is positively associated with both depressive symptoms and asthma severity in patients with asthma, according to a study published online Nov. 11 in the Journal of Allergy and Clinical Immunology: In Practice.Kazuma Kawamoto, M.D., from the Hiroshima University Graduate School of Biomedical and Health Sciences in Japan, and colleagues sought to identify factors associated with serum BDNF levels and depressive symptoms in 140 patients with asthma. The researchers found that serum BDNF levels were positively associated with the severity of depressive symptoms in patients with asthma. Elevated BDNF levels were associated with increased Hospital Anxiety and Depression Scale (HADS) depression scores and greater asthma severity in a multivariable linear regression analysis. High HADS depression scores were also associated with lower physical activity levels and poor asthma control."Unlike major depressive disorder, patients with asthma who have depressive symptoms show higher, not lower, serum BDNF levels," coauthor Hiroshi Iwamoto, M.D., Ph.D., also from Hiroshima University, said in a statement. "These results suggest that the biological mechanisms underlying depressive symptoms in asthma may be different from those in major depressive disorder."Several authors disclosed ties to the pharmaceutical industry.Abstract/Full Text.Sign up for our weekly HealthDay newsletter