Frequency of fatigue, emotional symptoms, and cognitive complaints in patients with recently diagnosed Multiple Sclerosis and their association with serum kynurenines and cytokines. A cross-sectional study

Abstract

Introduction: In Multiple Sclerosis (MS), three of the most frequent symptoms that most affect quality of life are fatigue, cognitive complaints, and emotional symptoms. Kynurenines (Kyns) and cytokines have previously been associated with fatigue and depression in different diseases. However, the association of Kyns and cytokines with these symptoms has been little studied in the early stages of MS.

Objective: Determine the frequency of fatigue, emotional symptoms, and cognitive complaints in patients with recently diagnosed MS, and to know if there is a correlation of these symptoms with serum Kyns and cytokines. 

Methodology: Prospective, cross-sectional, and analytical study. Patients with relapsing-remitting MS of both sexes, diagnosed for less than 2 years, with any EDSS score, and a group of healthy individuals were included. After signing informed consent, the following assessments were performed: EDSS, Beck Anxiety Inventory (BAI) and Beck Depression Inventory (BDI), Fatigue Impact Scale (FIS), MSNQ for cognitive complaints, and serum Kyns and cytokine profile were determined. Analysis: Univariate analysis was performed using T-test or Mann-Whitney U test, and Spearman correlation for serum biomarkers vs. clinical outcomes.

Results: 30 patients with MS were recruited (16 women, 53.3%, and 14 men, 46.7%; EDSS= 4.01 ± 2.26; disease duration 14.27 ± 9 months) and 35 healthy control participants. Average FIS score: 17.53; 56% of patients scored >17 points; 46% (n=14) presented significant depression; 40% (n=12) presented significant anxiety; 63.3% (n=19) presented cognitive complaints. A significant difference in levels of Kyn and kynurenic acid (KYNA) was observed between controls and patients (p=0.0014). A significant positive correlation was found between fatigue score and serum KYNA (p=0.0293, r=0.39); between depression and anxiety scores with IL-2 (r=0.6366; r=0.663); and between the MSNQ and KYNA (p=0.048, r=0.3634).

Conclusions: Fatigue, emotional symptoms, and cognitive complaints show an association with different markers of tryptophan metabolism and serum cytokines.