Exploring Transdiagnostic Psychological Processes in Functional Neurological Disorder

Overview

Functional neurological disorder (FND) is a little-known borderline disorder between psychiatry and neurology, which is benefiting from renewed research. Characterized by neurological symptoms in the absence of lesion damage corresponding to the symptom, the disorder is thought to be due to functional impairment of the central nervous system (DSM5 American Psychiatric Association, 2013). Symptoms are non-congruent, discordant and inconsistent with current anatomical knowledge. Several phenotypes are listed and may be associated: among the most frequent are motor and sensory disorders and dissociative crises or seizures. Common (Carson \& Lehn, 2016) and disabling (Gendre et al., 2019), the neurobiological and psychological mechanisms involved in NFT are becoming better understood, yet its etiology remains enigmatic (Hallett et al., 2022). Recent theoretical models consider neuropsychological constructs as central to the development and maintenance of the disorder, influenced by emotional processes (Drane et al., 2020). With a reputation for being difficult to treat, FND is a clinical challenge, and cognitive-behavioural therapy (CBT), although advocated, shows limits of efficacy mainly due to the complexity of clinical pictures and the heterogeneity of profiles (Gutkin et al., 2021). The CBTs described for FND are not specific to the disorder, and do not appear to be developed around a general theoretical framework defining the psychological mechanisms of the disorder (Richardson et al., 2020). Thus, there would be an interest in identifying characteristics in these patients that could guide therapeutic choices and implement a better therapeutic response (Gutkin et al., 2021). These findings, coupled with the growing interest in this complex disorder, confirm the need to deepen our knowledge of the psychological mechanisms involved in the disorder, with a view to developing and testing a specialized and flexible clinic (Aybek et al., 2020). Given the complexity of the disorder, a transdiagnostic approach is suggested (Saxena \& Perez, 2021). The transdiagnostic processual approach (Harvey et al., 2004) proposes an innovative conceptualization of mental health problems. This model sees the human biological system as leading to psychological disorder through the disruption of initially normal psychological processes (Kinderman, 2005). These processes refer to psychological mechanisms on which the clinician can act, via validated therapeutic strategies. Transdiagnostic treatments apply the same underlying treatment principles to all mental disorders, without tailoring the protocol to specific diagnoses (Menon et al., 2017). Considering the psychological mechanisms described as being altered in the disorder, etiological hypotheses, and literature data concerning transdiagnostic psychological processes, we raise the question of the involvement of such processes in FND. The aim of this study is to explore these processes in an FND population, with a view to refining our understanding of the psychological profile of these patients and guiding treatment.