Memory in multiple sclerosis: A reappraisal using the item specific deficit approach

Area of Science:

• Neuroscience
• Cognitive Psychology
• Clinical Neurology

Background:

• Multiple Sclerosis (MS) is frequently associated with significant memory impairment, affecting up to 65% of individuals.
• The precise nature of memory deficits in MS, whether in acquiring new information or retrieving it, remains debated.
• Previous research has not consistently evaluated both acquisition and retrieval processes simultaneously or adjusted for initial acquisition when assessing retrieval.

Purpose of the Study:

• To simultaneously quantify memory acquisition and retrieval abilities in individuals with MS.
• To apply the Item Specific Deficit Approach (ISDA) to assess list learning performance in two independent samples of MS patients and healthy controls.
• To investigate the role of initial acquisition in memory retrieval deficits within the MS population.

Main Methods:

• Two independent studies were conducted, involving a total of 164 people with MS and 69 healthy individuals.
• Participants underwent neuropsychological testing, and those with MS were categorized as globally impaired or unimpaired.
• The California Verbal Learning Test-II was used to assess new learning, with responses scored using the Item Specific Deficit Approach (ISDA).

Main Results:

• Both studies demonstrated that cognitively impaired individuals with MS exhibit deficits in both memory acquisition and retrieval.
• Cognitive impairment in MS had a medium effect size on acquisition and a large effect size on retrieval.
• Effect sizes for these memory impairments were nearly identical across both independent samples, indicating reliability.

Conclusions:

• The findings confirm that memory impairment in multiple sclerosis (MS) affects both the acquisition and retrieval of information.
• These results reconcile conflicting previous research by indicating that MS-related memory deficits are not solely attributable to either acquisition or retrieval, but rather both processes.
• The reliable and externally valid effects observed have implications for developing memory rehabilitation interventions that address both acquisition and retrieval in people with MS.