Autonomic, Endocrine and Inflammation Profiles in Functional Neurological Disorder: A Systematic Review and Meta-Analysis

Sara Paredes-Echeverri *, Julie Maggio, Indrit Bègue, Susannah Pick, Timothy Nicholson, David Perez

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

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Functional neurological disorder (FND) is a core neuropsychiatric condition. To date, promising yet inconsistently identified neural circuit profiles have been observed in patients with FND, suggesting important gaps remain in our systems-level neurobiological understanding. As such, other important physiological variables including autonomic, endocrine and inflammation findings need to be contextualized for a more complete mechanistic picture. Here, we performed a systematic review and meta-analysis of available case-control and cohort studies in FND. PubMed, PsycINFO and Embase databases were searched from January 1, 1900 to September 1, 2020 for studies that investigated autonomic, endocrine and/or inflammation markers in patients with FND. Sixty-six of 2,056 screened records were included in the review representing 1,699 patients, with data from 23 articles used in meta-analyses. Findings show that children/adolescents with FND vs. healthy controls (HCs) have increased resting heart rate; there is also a tendency towards reduced resting heart rate variability in patients with FND across the lifespan vs. HCs. In adults, peri-ictal heart rate differentiated those with functional seizures from individuals with epileptic seizures. Other autonomic and endocrine profiles in patients with FND were heterogeneous, with several studies highlighting the importance of individual differences. Inflammation research in FND remains in its early stages. Moving forward, there is a need to use larger sample sizes to consider the complex interplay between functional neurological symptoms and behavioral, psychological, autonomic, endocrine, inflammation, neuroimaging and epigenetic/genetic data. More research is also needed to determine whether FND is mechanistically (and etiologically) similar or distinct across phenotypes.
Original languageEnglish
JournalJournal of Neuropsychiatry and Clinical Neurosciences
Publication statusAccepted/In press - 7 May 2021


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