Does Exercise Influence Kynurenine/Tryptophan Metabolism and Psychological Outcomes in Persons With Age-Related Diseases? A Systematic Review

Anthony Lim; Christel Harijanto; Sara Vogrin; Gilles Guillemin; Gustavo Duque

doi:10.1177/1178646921991119

Does Exercise Influence Kynurenine/Tryptophan Metabolism and Psychological Outcomes in Persons With Age-Related Diseases? A Systematic Review

Int J Tryptophan Res. 2021 Feb 8:14:1178646921991119. doi: 10.1177/1178646921991119. eCollection 2021.

Authors

Anthony Lim^{1

2}, Christel Harijanto^{1

2}, Sara Vogrin^{1

3}, Gilles Guillemin⁴, Gustavo Duque^{1

2

3}

Affiliations

¹ Australian Institute for Musculoskeletal Science (AIMSS), The University of Melbourne and Western Health, St Albans, VIC, Australia.
² Melbourne Medical School-Western Precinct, The University of Melbourne, St Albans, VIC, Australia.
³ Department of Medicine-Western Health, Melbourne Medical School, The University of Melbourne, St Albans, VIC, Australia.
⁴ Neuroinflammation Group, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia.

Abstract

Background: The kynurenine (KYN) pathway has been implicated in many diseases associated with inflammation and aging ("inflammaging"). Targeting the kynurenine pathway to modify disease outcomes has been trialled pharmacologically, but the evidence of non-pharmacological means (ie, exercise) remains unclear.

Objective: We aim to assess the evidence of the effects of exercise on the kynurenine pathway and psychological outcomes.

Methods: Under Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) guidelines, a systematic literature search was performed in MEDLINE, EMBASE, EMCARE, and the Cochrane Central Registry of Controlled Trials. The main outcomes were changes in kynurenine pathway metabolite levels and psychological outcomes.

Results: Six studies were analyzed (total n = 379) with exercise demonstrating significant concomitant effects on kynurenine pathway metabolite levels and associated psychological outcomes in domains of somatization, anxiety, and depression.

Conclusion: Exercise has significant concomitant effect on kynurenine pathway metabolite levels and psychological outcomes. However, clear limitations exist in determining if the changes in the kynurenine pathway can fully explain the changes in psychological outcomes, or whether different diseases and exercise interventions act as confounding factors.

Keywords: Kynurenine; aging; exercise; inflammation; mental health; psychological outcomes; systematic review; tryptophan.

Publication types

Review