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Biological phenotypes underpin the physio-somatic symptoms of somatization, depression, and chronic fatigue syndrome

Authors

  • G. Anderson,

    1. CRC, Glasgow, UK
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  • M. Berk,

    1. School of Medicine, Deakin University, Melbourne, Vic., Australia
    2. Orygen Youth Health Research Centre, and the Centre for Youth Mental Health, Parkville, Vic., Australia
    3. The Florey Institute for Neuroscience and Mental Health, Parkville, Vic., Australia
    4. Department of Psychiatry, Melbourne University, Parkville, Vic., Australia
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  • M. Maes

    Corresponding author
    1. School of Medicine, Deakin University, Melbourne, Vic., Australia
    2. Department of Psychiatry, Faculty of Medicine, Pathumwan, Bangkok, Thailand
    3. Department of Psychiatry, Chulalongkorn University, Bangkok, Thailand
    • Prof. Dr. M. Maes, MD, PhD, Department of Psychiatry, Faculty of Medicine, 1873 Rama 4 Road, Pathumwan, Bangkok 10330, Thailand.

      E-mail: dr.michaelmaes@hotmail.com

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Abstract

Objective

Somatization is a symptom cluster characterized by ‘psychosomatic’ symptoms, that is, medically unexplained symptoms, and is a common component of other conditions, including depression and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). This article reviews the data regarding the pathophysiological foundations of ‘psychosomatic’ symptoms and the implications that this has for conceptualization of what may more appropriately be termed physio-somatic symptoms.

Method

This narrative review used papers published in PubMed, Scopus, and Google Scholar electronic databases using the keywords: depression and chronic fatigue, depression and somatization, somatization and chronic fatigue syndrome, each combined with inflammation, inflammatory, tryptophan, and cell-mediated immune (CMI).

Results

The physio-somatic symptoms of depression, ME/CFS, and somatization are associated with specific biomarkers of inflammation and CMI activation, which are correlated with, and causally linked to, changes in the tryptophan catabolite (TRYCAT) pathway. Oxidative and nitrosative stress induces damage that increases neoepitopes and autoimmunity that contribute to the immuno-inflammatory processes. These pathways are all known to cause physio-somatic symptoms, including fatigue, malaise, autonomic symptoms, hyperalgesia, intestinal hypermotility, peripheral neuropathy, etc.

Conclusion

Biological underpinnings, such as immune-inflammatory pathways, may explain, at least in part, the occurrence of physio-somatic symptoms in depression, somatization, or myalgic encephalomyelitis/chronic fatigue syndrome and thus the clinical overlap among these disorders.

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