Purpose of this review This narrative review provides an overview of functional cognitive disorder (FCD) as a cognitive subtype within the functional neurological disorder (FND) spectrum. It addresses the conceptual challenges, diagnostic criteria, and epidemiology of FCD, emphasizing the need for standardization of internal inconsistency and clearer diagnostic boundaries to improve clinical assessment and research. Recent findings FCD is characterized by persistent cognitive complaints disproportionate to objective performance, underpinned by metacognitive, attentional, and cognitive-behavioural dysfunction. Emerging evidence supports a predictive processing framework in which maladaptive top-down priors and attentional dysregulation perpetuate subjective cognitive deficits despite preserved or inconsistent objective cognitive performance. Diagnostic criteria and FCD checklists show promise, although challenges remain in standardizing neuropsychological assessments and integrating patient-reported experiences. Epidemiological data highlight the stability of FCD and its distinctiveness from neurodegenerative conditions, with a nonprogressive trajectory in most cases. Summary statement Defining and refining FCD through standardized criteria and mechanistic models is crucial for enhancing diagnostic accuracy, patient care, and research validity. Advancing our understanding of the pathophysiology of FCD within the FND framework will facilitate targeted interventions and improve trial cohort purity in neurodegenerative disease research. Future studies should focus on objective biomarkers and therapeutic strategies that address attentional and metacognitive dysfunction in FCD.
Adith et al. (Fri,) studied this question.