Association Between Salivary Cortisol, Xerostomia, and Nitric Oxide Levels in Patients With Multiple Sclerosis: A Cross-Sectional Study

Introduction: Multiple sclerosis (MS) is characterized by neuroinflammation, autonomic dysfunction, and alterations in the hypothalamic–pituitary–adrenal (HPA) axis. Salivary cortisol is a useful biomarker of physiological stress, while xerostomia and nitric oxide (NO) dysregulation may reflect autonomic or inflammatory changes frequently observed in MS. However, the relationship between cortisol, NO, xerostomia, and anxiety symptoms remains unclear. This study aimed to evaluate the associations among these biomarkers and clinical features in patients with MS.

Methods: A cross-sectional study was conducted in 39 patients with MS. Salivary cortisol and NO were measured through validated assays. Xerostomia was assessed using the Abslang Test (0 = no xerostomia, 1 = xerostomia). Anxiety levels were measured using the Beck Anxiety Inventory (BAI). MS duration was converted to years for analysis. Due to non-normal distributions, Spearman correlations and Mann–Whitney U tests were applied. Logistic regression was performed to examine the predictive value of cortisol for xerostomia, expressed as odds ratios (OR).

Results: Xerostomia was present in 41% of participants. Cortisol levels were higher in patients with xerostomia compared with those without (median 6.02 vs. 4.56; p = 0.050). Logistic regression showed that cortisol increased the odds of xerostomia by 33% per unit increase (OR = 1.33; 95% CI: 0.96–1.85; p = 0.085). Cortisol showed a weak-to-moderate positive correlation with xerostomia (ρ = 0.32; p = 0.047) and a moderate negative correlation with NO (ρ = –0.46; p = 0.0035). No associations were found between cortisol and age, MS duration, or anxiety scores.

Conclusions: Salivary cortisol is associated with xerostomia and lower NO levels in MS, suggesting a possible neuroendocrine–salivary pathway. Although the predictive effect of cortisol on xerostomia did not reach statistical significance, the consistent trends across analyses support a potential physiological link. Larger studies are warranted to further explore these interactions.