The neurobiology of functional neurological disorders characterised by impaired awareness

Abstract

We review the neurobiology of Functional Neurological Disorders (FND), i.e., neurological disorders not explained by currently identifiable histopathological processes, in order to focus on those characterised by impaired awareness (functionally impaired awareness disorders, FIAD), and especially, on the paradigmatic case of Resignation Syndrome (RS). We thus provide an improved more integrated theory of FIAD, able to guide both research priorities and the diagnostic formulation of FIAD. We systematically address the diverse spectrum of clinical presentations of FND with impaired awareness, and offer a new framework for understanding FIAD. We find that unraveling the historical development of neurobiological theory of FIAD is of paramount importance for its current understanding. Then, we integrate contemporary clinical material in order to contextualise the neurobiology of FIAD within social, cultural, and psychological perspectives. We thus review neuro-computational insights in FND in general, to arrive at a more coherent account of FIAD. FIAD may be based on maladaptive predictive coding, shaped by stress, attention, uncertainty, and, ultimately, neurally encoded beliefs and their updates. We also critically appraise arguments in support of and against such Bayesian models. Finally, we discuss implications of our theoretical account and provide pointers towards an improved clinical diagnostic formulation of FIAD. We suggest directions for future research towards a more unified theory on which future interventions and management strategies could be based, as effective treatments and clinical trial evidence remain limited.

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“…Current theories suggest that FND arises from networks in the brain that overlap with anxious and depressive disorder symptomatology and that many FND symptoms are essentially somatization of anxiety or depression‐spectrum pathology. More specifically, current theories postulate that FND is driven by impairments in self‐awareness and predictive coding, which are neurobiologically affected by stress, uncertainty, and neurally encoded beliefs, all of which are highly affected by mood and anxiety disorders (Milano et al., 2023 ). Our findings are similar to other studies of this population, which also demonstrated mean age of onset around 14–15, high rates of anxiety and depression, rapid progression of symptoms, and higher than expected prevalence of FND symptoms (Cavanna et al., 2023a ; Prato et al., 2022 ; Pringsheim et al., 2023 ).…”