Poststroke action slowing increases with task complexity and is linked to broader brain recruitment

Area of Science:

• Neuroscience
• Cognitive Neurology
• Neuropsychology

Background:

• Mechanisms of cognitive slowing after stroke are not well understood.
• Action speed is frequently impaired in stroke survivors.
• Understanding factors influencing slowing is crucial for rehabilitation.

Purpose of the Study:

• To characterize the relationship between cognitive test complexity and action speed slowing in stroke.
• To investigate how test sensitivity, brain area recruitment, and lesion load relate to the complexity effect.
• To explore correlations between individual slowing profiles and neuroimaging markers.

Main Methods:

• Analysis of 371 stroke patients and 581 controls from the GRECogVASC study.
• Assessment using eight time-limited tests varying in complexity (e.g., finger tapping, reaction time, Trail Making Test, fluency tests).
• Correlation of action speed, test sensitivity, and lesion volume with neuroimaging data (lesioned voxels, white matter hyperintensities, brain fraction).

Main Results:

• Stroke patients demonstrated significantly slower action speed compared to controls (p < .0001).
• Slowing increased significantly with test complexity (7.7% per step, p < .0001).
• More complex tests showed higher sensitivity to stroke effects, correlating with larger recruited brain networks and lesion volumes.

Conclusions:

• Stroke-induced slowing is a combination of general processing speed deficits and amplified slowing on complex tasks.
• Test sensitivity in stroke reflects the size and vulnerability of the engaged neural network.
• Findings provide insights into the neural organization of action speed and its disruption by stroke.