Cognitive Dysfunction in MS: Bridging the Gap Between Neurocognitive Deficits, Neuropsychological Batteries and MRI

Erica Grazioli; Ann E Yeh; Ralph HB Benedict; Joy Parrish; Bianca Weinstock-Guttman

Disclosures

Future Neurology. 2008;3(1):49-59. 

In This Article

Cognitive Areas Affected in MS

Episodic memory, processing speed and working memory are the most frequent areas of impaired cognition in MS.[12,13] MS patients perform attention-demanding tasks slowly, and when presented with new information recall less on a first learning attempt than non-MS subjects.[14,15,16,17,18,19] Improvement in subsequent trials of learning new information is also slower than in controls.[20] Deficits in executive function are also found in MS;[21] however, language and intelligence are typically spared.[3] The aspects of memory that are affected in MS are still debated based on contradictory data.[3,21,22] Usually, semantic knowledge and information storage are preserved in MS. Recall of newly learned information is often impaired and it is not yet clear if this impairment is related to a primary retrieval deficit or an impaired information-acquisition process.[21,22] Unlike patients with cortical dementias, such as Alzheimer's disease, MS patients seldom exhibit accelerated forgetfulness over time. It should also be noted that memory failures in MS are likely related, in part, to impairments in other areas, such as processing speed and higher executive function, which impact encoding processes.[23] An interesting area is the visuospatial domain, a region often found to be affected in MS patients. One study reported large variations in visuospatial testing performance. These abnormalities were seen in patients classified as cognitively impaired as well as those defined as cognitively unaffected.[24] This finding may be related directly to the frequent involvement of the anterior visual pathway in MS.

All of the above cognitive functions may be affected in relapsing-remitting MS patients, but declines in memory and abstract/conceptual reasoning appear to be more common in patients with a progressive course.[25,26] In some patients, perhaps as much as 10-15% of the MS population, multiple domains are affected, resulting in a clinical diagnosis of MS-associated dementia.[23] These patients are more likely to present with comorbid personality change or neuropsychiatric complications. As physical neurological deficits, such as visual dysfunction, may affect NP results, all NP testing of patients with MS should be carried out with the patients' heterogeneous neurological deficits in mind.

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