Neuropsychologic status in multiple sclerosis after treatment with glatiramer

Background: Glatiramer acetate (Copaxone) therapy reduces clinical disease activity in relapsing-remitting multiple sclerosis (MS). Objective: To study the effect of glatiramer therapy on neuropsychologic function as part of a randomized, placebo-controlled, multicenter trial. Methods: Two hundred forty-eight patients with relapsing-remitting MS and mild to moderate disability (Expanded Disability Status Scale score, <5.0) were tested before and 12 and 24 months after randomization to administration of glatiramer acetate, 20 mg/d, or matching placebo. Neuropsychologic tests examined 5 cognitive domains most often disrupted in patients with MS: sustained attention, perceptual processing, verbal and visuospatial memory, and semantic retrieval. Results: Baseline neuropsychologic test performance was similar in both treatment groups and was within normal range, except for impaired semantic retrieval. Mean neuropsychologic test scores were higher at 12 and 24 months than at baseline, and no differences were detected between treatment groups over time. No significant interactions were detected between treatment and either time or baseline impairment. Conclusions: Our 2-year longitudinal study showed no effect of glatiramer therapy on cognitive function in relapsing-remitting MS. Although it is possible that glatiramer therapy has no effect on cognitive function, the lack of measurable decline in cognitive function in both patient groups for 2 years limits the opportunity for glatiramer to demonstrate a therapeutic effect by minimizing such decline. Emerging treatments for MS should continue to be examined for their effect on cognitive impairment because it can be a critical determinant of disability. A greater understanding of the natural history of cognitive decline in MS is essential for a rational design of these drug trials.