Looking into cognitive impairment in primary-progressive multiple sclerosis

Area of Science:

• Neuroscience
• Ophthalmology
• Radiology

Background:

• Cognitive impairment in primary-progressive multiple sclerosis (PP-MS) is linked to brain atrophy.
• Brain volume computation is resource-intensive and not widely available clinically.
• Retinal atrophy metrics may serve as a proxy for gray matter atrophy in PP-MS.

Purpose of the Study:

• To investigate the predictive role of retinal atrophy metrics on cognitive decline in PP-MS.
• To assess optical coherence tomography (OCT) metrics as potential indicators of neurodegeneration.
• To explore the mediating role of gray matter atrophy in the relationship between retinal measures and cognition.

Main Methods:

• Twenty-five PP-MS patients underwent OCT and 3.0-T MRI.
• Cognitive function was assessed using the Brief International Cognitive Assessment for Multiple Sclerosis.
• Stepwise logistic regression analyzed OCT metrics (retinal nerve fiber layer, GCIPL, macular volume) for prediction of cognitive impairment.

Main Results:

• Ganglion cell + inner plexiform layer (GCIPL) thickness was associated with and predictive of cognitive impairment (P=0.036).
• GCIPL correlated with normalized brain volume (P=0.047) and thalamic volume (P=0.001).
• Thalamic volume showed a near-mediating effect between GCIPL and cognitive scores (P=0.063).

Conclusions:

• GCIPL thickness is a valid indicator of neurodegeneration in PP-MS.
• GCIPL offers higher specificity for neuronal loss compared to brain atrophy.
• GCIPL provides a non-invasive, quantitative method for monitoring cognitive impairment related to neuronal loss in PP-MS.