Tired minds, normal scores: rethinking cognitive fatigue in multiple sclerosis

Area of Science:

• Neuroscience
• Clinical Psychology
• Rehabilitation Medicine

Background:

• Cognitive fatigue is a primary disabling symptom in multiple sclerosis (MS), frequently underrecognized and undertreated.
• It is often misdiagnosed as general fatigue or overlooked due to limitations in standard neuropsychological assessments.
• Current assessment methods rely on brief, decontextualized measures that fail to capture the dynamic nature of cognitive fatigability.

Purpose of the Study:

• To advocate for a paradigm shift in conceptualizing and managing cognitive fatigue in MS.
• To redefine cognitive fatigue as a core dysfunction in sustained cognitive effort, distinct from general or subjective fatigue.
• To highlight the dissociation between perceived fatigue and objective fatigability, indicating flaws in current assessment tools.

Main Methods:

• Review of existing evidence on cognitive fatigue in MS.
• Conceptual analysis differentiating cognitive fatigue from general and subjective fatigue.
• Proposal for integrating prolonged, dynamic, and ecologically valid assessment methods.

Main Results:

• Evidence demonstrates a frequent dissociation between subjective fatigue and objective fatigability in MS.
• Standard brief assessments are inadequate for capturing the complexities of cognitive fatigue.
• Prolonged, dynamic, and ecologically valid measures are crucial for accurate assessment.

Conclusions:

• Cognitive fatigue requires repositioning as a distinct clinical target with specific identification, monitoring, and intervention strategies.
• Integrating dynamic and ecologically valid measures like extended neuropsychological tasks and digital phenotyping is essential.
• Reframing cognitive fatigue will lead to more accurate diagnostics and individualized care for MS patients.