Cognitive impairment of Japanese multiple sclerosis patients: Follow-up study using BRB-N assessment tool.

OBJECTIVES: The purpose of this study was to evaluate cognitive function in patients with multiple sclerosis (MS), compared with control subjects, and to establish whether decline of cognitive function continues in the patients during remission.

METHODS: The Japanese version of the Brief Repeatable Battery of Neuropsychological tests (BRB-N), which includes the selective reminding test (SRT), spatial recall test (SPART), symbol digit modalities test (SDMT), paced auditory serial addition test (PASAT), and the word list generation test (WLG), was performed in 34 Japanese patients with MS (8 males, 26 females; mean age, 42 years) and in 37 age- and education-matched healthy controls (20 males, 17 females; mean age, 36 years). BRB-N was conducted at intervals of two years for MS patients who remained in remission, and the cognitive changes were evaluated by comparing the results with those of the initial examination at entry into the study.

RESULTS: The MS patients showed lower BRB-N scores than controls, with high significance in the SRT, SRT-D, SDMT and PASAT tests (p<0.01). The BRB-N scores of the MS patients who remained in remission were not significantly changed for at least 2 years.

CONCLUSIONS: The Japanese version of the BRB-N is useful to clarify the nature of cognitive impairment in Japanese MS patients. Based on this neuropsychological assessment, we suggest that working memory and information-processing speed are key deficits. Patients who remained in remission showed little or no further impairment of cognitive functions for at least two years.