Brain-Derived Neurotrophic Factor Levels Are Associated With Depressive Symptoms in Patients With Asthma

Patients with major depressive disorder exhibit reduced central and circulatory levels of brain-derived neurotrophic factor (BDNF), with serum BDNF being proposed as a potential biomarker for major depression. Contrastingly, animal studies have suggested that elevated BDNF levels may be associated with airway pathology in asthma.

This study aimed to identify factors associated with serum BDNF levels and depressive symptoms in patients with asthma.

We included 140 patients with asthma. Serum BDNF levels were measured using an enzyme-linked immunosorbent assay. Depressive and anxiety symptoms were evaluated using the Hospital Anxiety and Depression Scale (HADS). Daily physical activity was assessed using a triaxial accelerometer. First, we investigated factors associated with serum BDNF levels in patients with asthma. Second, we examined clinical variables related to HADS depression scores.

Serum BDNF levels were positively associated with the severity of depressive symptoms in patients with asthma. Multivariable linear regression analysis demonstrated that elevated BDNF levels were associated with increased HADS depression scores and greater asthma severity. In addition, high HADS depression scores were also associated with lower physical activity levels and poor asthma control.

Serum BDNF levels are positively associated with both depressive symptoms and asthma severity in patients with asthma. These findings suggest that the mechanisms underlying depressive symptoms in patients with asthma may differ from those in major depression, particularly with respect to the role of BDNF.