Exhaled Nitric Oxide Decreases during Academic Examination Stress in Asthma

Fractional exhaled nitric oxide (FeNO) is known to vary with multiple endogenous and exogenous factors. Laboratory stress and depressive mood have been associated with altered FeNO levels, but little is known about the susceptibility of FeNO to longer-lasting states of psychological stress in asthma.

We sought to study changes in FeNO, lung function, and endogenous cortisol levels in students in a low-stress period during the academic term and in high-stress periods of up to 5 days during final exams.

One hundred nine participants (35 with asthma) enrolled in a final examination stress study were assessed during the academic term (low stress) and during final exams (high stress). FeNO, spirometric lung function (FEV1, peak flow), salivary cortisol, and negative affect were measured at three time points. Control variables were medication use, cold symptoms, sex, and age.

FeNO decreased substantially from low-stress baseline to the high-stress examination periods, with more pronounced decreases occurring in subjects with asthma (-11.5 ppb) than control subjects (-1.2 ppb). FEV1 decreased in both groups. Negative affect and cortisol increased during final exams, but these increases were smaller in asthma. Greater initial depression and greater cortisol increases were related to larger FeNO decreases during the final exam period, the latter only in asthma. Inhaled corticosteroid use did not affect these changes.

Psychological stress and depressive mood are accompanied by decreases in both FeNO and lung function in asthma. Fluctuations related to life stress and mood levels should be considered in FeNO monitoring for asthma.