BDNF and asthma: Plasma BDNF levels were significantly higher in both non-severe (0.91 pg/mL, 0.50–1.22; p = 0.005) and severe asthma patients (0.88 pg/mL, 0.61–1.29; p = 0.0004) compared to the control group (0.56 pg/mL, 0.45–0.92).