Impact of Vitamin D and Smoking on Long-Term Cognition in MS

The BENEFIT study was an evaluation of early versus delayed treatment with interferon for people who presented with a clinically isolated syndrome. At baseline and 6, 12, and 24 months, the researchers measured participants' neurofilament levels, cognitive function by the Paced Auditory Serial Addition Test (PASAT), vitamin D levels, Epstein-Barr virus (EBV) EBNA-1 immunoglobulin G (IgG), and a nicotine metabolite. The investigators obtained follow-up data at year 11 for 278 of the original 468 patients.

Individuals with higher vitamin D levels were less likely to score below the median PASAT at

year 11 (odds ratio for each 50 nmol/L increase in mean level, 0.35; 95% confidence interval, 0.14–0.89). Smoking demonstrated a nonsignificant trend…