functional disorders critique – American ME and CFS Society

Introduction:

In the past 4 years of COVID-19 and Long COVID, a renewed interest in postural orthostatic tachycardia syndrome (POTS) and other autonomic disorders brought to light a common misconception that these disorders are based in or are associated with functional neurologic disorder (FND). Recently, one narrative review attempted to link autonomic disorders and autonomic nervous system dysfunction with symptoms of FND (1). Others have similarly suggested that Long COVID may be based in functional or somatic etiology (2–5). As medical professionals with expertise in autonomic disorders, we would like to emphasize the distinction between autonomic disorders, autonomic symptoms and FND in order to ensure that appropriate diagnostic and therapeutic pathways are implemented by clinicians.

Source: Blitshteyn S, Treisman GJ, Ruhoy IS, Saperstein DS, Schofield JR, Goodman BP, Davenport TE, Cutchins AC and Grubb BP (2024) Postural orthostatic tachycardia syndrome and other common autonomic disorders are not functional neurologic disorders. Front. Neurol. 15:1490744. doi: 10.3389/fneur.2024.1490744 https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2024.1490744/full (Full text)

Abstract:

PURPOSE OF REVIEW: The aim of this paper is to review recent findings on inflammatory and oxidative and nitrosative stress (IO&NS) pathways in chronic fatigue and somatization disorder.

RECENT FINDINGS: Activation of IO&NS pathways is the key phenomenon underpinning chronic fatigue syndrome (CFS): intracellular inflammation, with an increased production of nuclear factor kappa beta (NFkappabeta), cyclo-oxygenase-2 (COX-2) and inducible NO synthase (iNOS); and damage caused by O&NS to membrane fatty acids and functional proteins. These IO&NS pathways are induced by a number of trigger factors, for example psychological stress, strenuous exercise, viral infections and an increased translocation of LPS from gram-bacteria (leaky gut). The ‘psychosomatic’ symptoms experienced by CFS patients are caused by intracellular inflammation (aches and pain, muscular tension, fatigue, irritability, sadness, and the subjective feeling of infection); damage caused by O&NS (aches and pain, muscular tension and fatigue); and gut-derived inflammation (complaints of irritable bowel). Inflammatory pathways (monocytic activation) are also detected in somatizing disorder.

SUMMARY: ‘Functional’ symptoms, as occurring in CFS and somatization, have a genuine organic cause, that is activation of peripheral and central IO&NS pathways and gut-derived inflammation. The development of new drugs, aimed at treating those disorders, should target these IO&NS pathways.

Source: Maes M. Inflammatory and oxidative and nitrosative stress pathways underpinning chronic fatigue, somatization and psychosomatic symptoms. Curr Opin Psychiatry. 2009 Jan;22(1):75-83. https://www.ncbi.nlm.nih.gov/pubmed/19127706