Risk, Precipitating, and Perpetuating Factors in Functional Neurological Disorder: A Systematic Review Across Clinical Subtypes

Background: Functional Neurological Disorder (FND) encompasses conditions with neurological symptoms inconsistent with structural pathology, arising instead from complex interactions between psychological, biological, and social factors. Despite growing research, the etiological and risk factor landscape remains only partially understood, complicating diagnosis and treatment. Objective: This systematic review maps risk factors for major FND subtypes such as functional seizures (psychogenic non-epileptic seizures or PNES), functional cognitive disorder (FCD), functional movement disorders (FMD), functional weakness and sensory disturbances, functional visual symptoms, and functional gait abnormalities by categorizing predisposing, precipitating, and perpetuating influences. Methods: A systematic search of PubMed, PsycINFO, Scopus, and Web of Science initially identified 245 records. After removal of 64 duplicates, 181 studies were screened by title and abstract. Of these, 96 full texts were examined in detail, and finally 23 studies met the predefined inclusion criteria. Data were extracted and analyzed thematically within a biopsychosocial framework, with results summarized in subtype-specific profiles. Results: Childhood adversity, especially emotional, physical, or sexual abuse, emerged as a robust and consistent predisposing factor across PNES cohorts. Psychiatric history (notably anxiety, depression, and PTSD), neurodevelopmental traits (more frequent in FCD), and personality patterns such as alexithymia and somatization also contributed to vulnerability. Precipitating influences included acute psychological stress, intrapersonal conflict, or concurrent medical illness. Perpetuating factors comprise maladaptive illness beliefs, avoidance behaviors, insufficient explanation or validation by healthcare providers, and secondary gains related to disability. While several risk factors were shared across subtypes, others appeared subtype-specific (trauma was especially associated with PNES, whereas neurodevelopmental traits were more characteristic of FCD). Conclusions: FND arises from a dynamic interplay of predisposing, precipitating, and perpetuating factors, with both shared and subtype-specific influences. Recognizing this heterogeneity can enhance diagnostic precision, guide tailored intervention, and inform future research into the neurobiological and psychosocial mechanisms underlying FND.