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Study Determines That 2 Forms of Multiple Sclerosis Exhibit Differences in Cognitive Ability

October 28, 2015

In a recent study published in the journal PLOS One, researchers set out to determine the differences in cognitive performance in patients with relapsing-remitting multiple sclerosis (RRMS) and patients with primary progressive multiple sclerosis (PPMS) to underscore the importance of customized intervention in these two MS forms.

The vast majority of the patients (85%) with multiple sclerosis (MS) are diagnosed with RRMS. These patients usually show first signs of the disease in their early 20s, and experience relapses from time to time, followed by weeks, months, or years of remission.

On the other side of the spectrum, only 10% of MS patients are diagnosed with PPMS. There are no well-defined attacks and no remission period. Treatment for PPMS has not been as successful.

Dr. Matilde Inglese, from the Department of Neurology, Mount Sinai School of Medicine in New York, assessed 57 patients (42 RRMS patients and 15 PPMS) using MRI and a battery of tests to measure cognitive performance, brain volumes, and cortical thickness.

Results showed that cognitive performance in patients with RRMS was associated with normalized brain volume (NBV), normalized white matter volume (NWMV), normalized gray matter volume (NGMV), lesion volume and cortical thickness of the temporal lobe, parietal lobe and frontal lobe, while cognitive performance in patients with PPMS was associated with NBV, NWMV, lesion volume and the volumes of the thalamus, hippocampus and putamen. The team found no significant differences in MRI correlates of cognitive impairment between RRMS and PPMS patients, although an association was found in RRMS and MRI measures of cortical gray matter injury, and PPMS and MRI measures of subcortical gray matter injury.

Based on the results, the team concluded that cortical and subcortical gray matter injury may play a different role regarding disease course. “Future research should involve larger cohorts of patients with progressive MS, and investigate in a longitudinal fashion whether the development of cognitive impairment in different groups of patients is associated with specific patterns of MRI metrics. This would help identify patients at higher risk of cognitive decline and allow early and tailored intervention with both pharmacological and rehabilitative treatments,” the researchers wrote.