The effects of long-term interferon-beta-1b treatment on cognitive functioning in multiple sclerosis: a 16-year longitudinal study

Background: Multiple sclerosis (MS) is a progressive disease of the central nervous system that affects cognition. Short-term treatment with interferon-beta-1b (IFN-b-1b) has been shown to have beneficial effects on cognition. Objective: The objective of this paper is to evaluate the effects of IFN-b-1b on cognitive functioning in patients with MS over the course of 16 years. Methods: Sixteen subjects with relapsing-remitting MS participated in the study. Nine of these subjects received IFN-b-1b, while seven received placebo treatment in the pivotal MS trial. After five years, all subjects were switched to IFN-b-1b treatment. At two and four years into the study, all subjects underwent a brief neuropsychological test battery, magnetic resonance imaging (MRI), and neurologic ratings; measures were repeated at 16 years. Results: Across the total cohort, cognitive functioning remained relatively stable over the course of 16 years. The placebo/IFN-b-b group exhibited increased visual memory performance relative to the IFN-b-1b treatment group, but had a greater decline in verbal memory. Initial MRI lesion load demonstrated a significant, negative correlation with overall cognitive performance at 16 years (p = 0.00). Conclusion: We conclude that IFN-b-1b has beneficial effects on long-term cognition outcomes in MS.