Increases in exhaled nitric oxide after acute stress: association with measures of negative affect and depressive mood.

Background: Increases in fractional exhaled nitric oxide (FeNO) have been observed after acute laboratory stress, which could indicate a strengthening of immune defenses in acute stress because of the quick onset of the response and the role of nitric oxide in airway-protective functions. In addition, because sustained psychological distress and depression are known to deteriorate immune defenses systems, they may dampen the FeNO response to acute stress.

Methods: FeNO and negative affect were measured before and after a speech and mental arithmetic stressor. We examined the association of stress-induced FeNO changes with momentary negative affect and questionnaires of perceived stress, anxious mood, and depressive mood in 39 asthma patients and 41 healthy controls.

Results: FeNO increased from baseline to stress in participants with asthma (from 3.38 [0.102] to 3.46 [0.103] ln(ppb)) and controls (2.86 [0.098] to 2.92 [0.099]; F(4,141) = 3.26, p = .014), but the magnitude of the FeNO response did not differ between groups (F < 1). Only low levels of depressive mood were associated with FeNO increases after stress (most pronounced at 0 minute poststress; t(76) = 3.87, p < .001). In contrast, only higher perceived stress was associated with FeNO increases (most pronounced at 0 minute poststress; t(75) = 4.09, p < .001), and momentary negative affect was associated with higher FeNO throughout assessments (β = 0.08, t(114) = 8.27, p = .005). Associations of FeNO with psychological variables were largely unrelated to asthma status and inhaled corticosteroid use.

Conclusions: Depressive mood is associated with a reduced mobilization of airway nitric oxide in acute stress, whereas other indicators of negative affect are positively associated with overall FeNO levels and reactivity.