Impaired cognition is measurable up to a month before relapse in patients with MS and can last 1.5 years before returning to normal, Swedish researchers say.

Results from their nationwide cohort study suggest that the effects of relapse on cognition are longer than previously thought and underline the importance of reducing relapse to preserve cognitive function.

Using data from nearly 3900 adults (mean age 32) with incident relapsing-remitting MS, the authors quantified the relationship between relapse and cognition, which was assessed via the symbol digit modalities test (SDMT).

Most patients in the majority-female cohort were receiving second-line therapy at baseline, and more than 31,000 SDMTs were recorded over an average 11 years’ follow-up.