Two years' effect of dimethyl fumarate on focal and diffuse gray matter pathology in multiple sclerosis.

BACKGROUND

Data on the effect of dimethyl fumarate (DMF) on focal and diffuse gray matter (GM) damage, a relevant pathological substrate of multiple sclerosis (MS)-related disability are lacking.

OBJECTIVE

To evaluate the DMF effect on cortical lesions (CLs) accumulation and global and regional GM atrophy in subjects with relapsing-remitting MS.

METHODS

A total of 148 patients (mean age 38.1 ± 9.7 years) treated with DMF ended a 2-year longitudinal study. All underwent regular Expanded Disability Status Scale (EDSS assessment), and at least two 3T-magnetic resonance imaging (MRI) at 3 and 24 months after DMF initiation. CLs and changes in global and regional atrophy of several brain regions were compared with 47 untreated age and sex-matched patients.

RESULTS

DMF-treated patients showed lower CLs accumulation (median 0[0-3] vs 2[0-7],  < 0.001) with respect to controls. Global cortical thickness ( < 0.001) and regional thickness and volume were lower in treated group (cerebellum, hippocampus, caudate, and putamen:  < 0.001; thalamus  = 0.03). Lower relapse rate (14% vs 40%,  < 0.001), EDSS change (0.2 ± 0.4 vs 0.4 ± 0.9,  < 0.001), and new WM lesions (median 0[0-5] vs 2[0-6],  < 0.001) were reported. No severe adverse drug reactions occurred.

CONCLUSIONS

Beyond the well-known effect on disease activity, these results provide evidence of the effect of DMF through reduced progression of focal and diffuse GM damage.