Cognitive fatigability in multiple sclerosis: How does performance decline over time on the Paced Auditory Serial...

Area of Science:

• Neuroscience
• Clinical Psychology
• Rehabilitation Science

Background:

• Cognitive fatigability (CF) is the inability to sustain optimal cognitive performance.
• The precise timing of performance decline in cognitive tasks, like the Paced Auditory Serial Addition Test (PASAT), remains unclear for individuals with multiple sclerosis (PwMS).

Purpose of the Study:

• To compare the time-course of cognitive performance decline on the PASAT between PwMS and healthy controls.
• To investigate if CF manifests as a performance breakdown at a specific task moment or a continuous decline.

Main Methods:

• Administered 3" and 2" PASAT to 178 PwMS and 186 controls.
• Utilized repeated measures ANOVAs to analyze cumulative error rates and error development across trials.
• Exploratory ANOVAs examined the influence of stimulus complexity (single vs. double-digit answers).

Main Results:

• PwMS exhibited higher overall error rates and greater vulnerability to CF than controls, particularly on the 3" PASAT.
• On the 3" PASAT, PwMS showed significantly more cumulative errors by Trial 37.
• The rate of error generation in PwMS was linear and consistent from the beginning to the end of the task.

Conclusions:

• The 3" PASAT is more sensitive to CF differences than the 2" PASAT.
• PwMS demonstrate a linear decline in cognitive performance throughout the PASAT, rather than a specific breakdown point.
• Individuals with MS struggle with sustained cognitive effort, showing a steady, steeper decline in performance over time.