[Functional cognitive disorders: How to diagnose and manage them? Discussion based on a clinical case]

Functional cognitive disorder (FCD) is a frequent and underrecognized cause of cognitive complaints. Long regarded as a diagnosis of exclusion, conceptual advances have allowed this condition to be integrated within the nosological framework of functional neurological disorders, and to be approached through a positive definition based on the identification of internal inconsistency signs. Nevertheless, establishing a diagnosis of FCD can prove challenging in clinical practice, particularly due to overlapping features with the main differential diagnoses. Through the illustration of a typical clinical case, this article aims to support the positive diagnostic criteria for FCD, and to highlight the key arguments allowing FCD to be distinguished from its main differential diagnoses: cognitive symptoms related to depressive disorder, neurodegenerative diseases at the prodromal stage, and malingering. Diagnosing FCD requires a comprehensive patient evaluation, integrating a qualitative analysis of the interview and the patient's conversational profile alongside the assessment of symptoms, physical examination, and neuropsychological testing.