Predicting conversion to multiple sclerosis by assessing cognitive impairment in radiologically isolated syndrome

Up to a third of patients with radiologically isolated syndrome (RIS) exhibit lower-than-expected cognitive performances in neuropsychological evaluations, but the relationship between cognitive impairment (CI) and quantitative magnetic resonance (MRI) measures has not been stablished. Furthermore, the prognostic role of CI in RIS for conversion to MS is currently unknown. We assessed 17 patients with RIS and 17 matched healthy controls (HC) with a neurophychological battery and a 3T MRI. Six patients (35,3%) fulfilled our criterion for CI (scores 2 SDs below the mean of HC in at least two cognitive tests) (ci-RIS). The ci-RIS subgroup showed lower values of normalized brain and gray matter volumes when compared to HC. After a median follow-up time of 4.5 years, the ci-RIS subgroup presented a higher conversion rate to MS, suggesting that CI might be an independent risk factor for conversion to MS.