Anxiety due to Long COVID is partially driven by activation of the tryptophan catabolite (TRYCAT) pathway

Hussein Kadhem Al-Hakeim; Anwar Khairi Abed; Abbas F Almulla; Shatha Rouf Moustafa; Michael Maes

doi:10.1016/j.ajp.2023.103723

Anxiety due to Long COVID is partially driven by activation of the tryptophan catabolite (TRYCAT) pathway

Asian J Psychiatr. 2023 Oct:88:103723. doi: 10.1016/j.ajp.2023.103723. Epub 2023 Aug 6.

Authors

Hussein Kadhem Al-Hakeim¹, Anwar Khairi Abed¹, Abbas F Almulla², Shatha Rouf Moustafa³, Michael Maes⁴

Affiliations

¹ Department of Chemistry, College of Science, University of Kufa, Kufa 54002, Iraq.
² Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Medical Laboratory Technology Department, College of Medical Technology, The Islamic University, Najaf, Iraq.
³ Clinical Analysis Department, College of Pharmacy, Hawler Medical University, Erbil, Iraq.
⁴ Department of Psychiatry, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; Department of Psychiatry, Medical University of Plovdiv, Plovdiv, Bulgaria; Research Institute, Medical University of Plovdiv, Plovdiv, Bulgaria; Kyung Hee University, 26 Kyungheedae-ro, Dongdaemun-gu, Seoul 02447, the Republic of Korea; Sichuan Provincial Center for Mental Health, Sichuan Provincial People's Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu 610072, China; Key Laboratory of Psychosomatic Medicine, Chinese Academy of Medical Sciences, Chengdu 610072, China. Electronic address: dr.michaelmaes@hotmail.com.

PMID: 37567082
DOI: 10.1016/j.ajp.2023.103723

Abstract

This study examines whether activation of the tryptophan catabolite (TRYCAT) pathway is associated with anxiety symptoms due to Long COVID. We selected 90 participants, 60 Long COVID patients and 30 individuals without any symptoms following acute COVID-19 infection. Using cluster analysis and the Hamilton Anxiety Rating scale (HAMA) score, the pure HAMA anxiety score, serum tryptophan (TRP) and kynurenine (KYN), the KYN/TRP ratio (all measured during Long COVID), and oxygen saturation (SpO2) (measured during the acute phase of COVID-19), we were able to classify Long COVID patients into two distinct clusters with an adequate silhouette cohesion and separation index (0.58): cluster 1 (n = 61) and cluster 2 (n = 29). Cluster 2 patients had lower SpO2 and TRP levels, as well as higher KYN, KYN/TRP ratio, and HAMA scores than cluster 1. Regression analysis revealed that the KYN/TRP ratio explained 14.4 % of the variance in the HAMA score (F = 14.81, df = 1/88, p = 0.001). In addition, regression analysis revealed that SpO2 partially explained the variance in serum TRP (r = 0.396, p = 0.005), KYN/TRP ratio (r = - 0.248, p = 0.018), and the HAMA score (r = - 0.279, p = 0.008). The current data imply that decreased SpO2 during the acute phase of COVID-19 infection is predictive of anxiety caused by Long COVID. Our data reveal that around 32 % of Long COVID patients have elevated IDO activity in association with elevated anxiety.

Keywords: Anxiety; Inflammation; Kynurenine; Mood disorders; Neuro-immune; Tryptophan.

Publication types

Letter

MeSH terms

Anxiety
COVID-19*
Humans
Kynurenine
Post-Acute COVID-19 Syndrome
Tryptophan* / metabolism

Substances

Tryptophan
Kynurenine