Functional cognitive disorder: dementia's blind spot

Area of Science:

• Neurology
• Psychiatry
• Cognitive Science

Background:

• A growing number of cognitive difficulties stem from functional causes, primarily indicated by internal inconsistency.
• Functional cognitive disorder (FCD) is a cognitive variant of functional neurological disorder, characterized by impairing or distressing symptoms not better explained by other conditions.
• Mild cognitive impairment (MCI) is frequently used but is an etiology-neutral term, encompassing various underlying causes, including FCD.

Purpose of the Study:

• To define functional cognitive disorder (FCD) and its relationship with mild cognitive impairment (MCI).
• To highlight clinical features for positive FCD diagnosis and red flags for alternative conditions.
• To improve the recognition and management of non-neurodegenerative cognitive disorders.

Main Methods:

• Review of existing literature and clinical observations.
• Development of a preliminary definition for FCD.
• Analysis of diagnostic criteria and biomarkers for cognitive disorders.

Main Results:

• FCD is likely underdiagnosed and represents a significant proportion of MCI cases not progressing to dementia.
• Positive diagnostic identifiers for FCD can distinguish it from neurodegenerative conditions.
• Viewing MCI as a descriptive term with a broad differential diagnosis, including FCD, is crucial.

Conclusions:

• FCD is a distinct clinical entity that requires recognition for accurate diagnosis and treatment.
• Distinguishing FCD from neurodegenerative causes is essential for effective patient management.
• Further research and clinical practice should incorporate FCD to improve patient outcomes.