The relationship between processing speed and verbal and non-verbal new learning and memory in progressive multiple...

Area of Science:

• Neuroscience
• Cognitive Psychology
• Clinical Neurology

Background:

• Processing speed (PS) deficits are the most frequent cognitive impairment in multiple sclerosis (MS), often preceding other cognitive issues like learning and memory problems.
• Impaired PS is hypothesized to be a direct consequence of MS pathology, negatively impacting learning abilities.
• This study investigates the relationship between PS and learning in a large cohort of individuals with progressive MS.

Purpose of the Study:

• To examine the association between processing speed and learning in individuals with progressive multiple sclerosis.
• To determine the predictive power of a standard PS test for different learning and memory deficits in MS.
• To evaluate the utility of the Symbol Digit Modalities Test (SDMT) in identifying cognitive impairments in progressive MS.

Main Methods:

• Analysis of baseline data from a North American and European randomized clinical trial involving 275 participants with progressive MS.
• Utilized the Symbol Digit Modalities Test (SDMT) as a measure of processing speed.
• Employed the California Verbal Learning Test-II (CVLT-II) and the Brief Visuospatial Memory Test-Revised (BVMT-R) to assess learning and memory.

Main Results:

• The SDMT showed a statistically significant correlation with both CVLT-II (r=0.21, p=0.0003) and BVMT-R (r=0.516, p<0.0001).
• Receiver operating characteristic (ROC) analysis indicated a 61% chance of predicting impaired CVLT-II performance from SDMT scores (AUC=0.61).
• ROC analysis demonstrated a 77% chance of distinguishing impaired from non-impaired BVMT-R performance using SDMT scores (AUC=0.77).

Conclusions:

• The SDMT has a limited ability to predict verbal learning deficits in progressive MS, with predictive accuracy only slightly better than chance.
• The SDMT is more effective in predicting visuospatial memory impairments in this population, showing substantial predictive power.
• These findings suggest that processing speed, as measured by the SDMT, has differential impacts on various cognitive domains in progressive MS, with a stronger link to visuospatial memory.