Abstract
The diagnosis and monitoring of progressive multiple sclerosis (PMS) require further development of fast and effective clinical tools. Relations between MRI-based brain atrophy measures and cognitive impairment in people with primary progressive and secondary progressive MS (PwPPMS, n = 20 and PwSPMS, n = 19, respectively) were investigated in a prospective study with follow-up after a mean 14.97 ± 4.67 months. MRI analysis showed that at baseline and follow-up in PwSPMS, the left thalamic fraction and corpus callosum fraction were significantly lower than in PwPPMS (baseline: 0.39 ± 0.04 vs. 0.44 ± 0.06, p = 0.0203 and 0.26 ± 0.05 vs. 0.30 ± 0.05, p = 0.0097; respectively and follow-up: 0.40 ± 0.04 vs. 0.44 ± 0.07, p = 0.0443 and 0.25 ± 0.06 vs. 0.30 ± 0.05, p = 0.0103, respectively). In contrast, only at baseline, PwPPMS had a significantly lower cerebellar white matter fraction (CWMF) than PwSPMS (1.83 ± 0.20 vs. 2.01 ± 0.24, p = 0.0132). No other significant differences were observed in the MRI fractions at either study time point or in the changes of the MRI fractions between the PwPPMS and PwSPMS. However, a significant decline in the right putaminal fraction was found during observation in PwSPMS (0.332% ± 0.05% vs. 0.328% ± 0.05%, p = 0.0479). Cognitive test scores and their changes did not differ significantly between the subgroups. Declines in the Brief Visuospatial Memory Test Revised in the whole PMS group (18.74 ± 7.43 vs. 17.03 ± 7.61, p = 0.0209) and in PwPPMS (19.50 ± 8.29 vs. 17.20 ± 7.72, p = 0.0338), as well as in the Brief International Cognitive Assessment for Multiple Sclerosis in PwPPMS (1.05 ± 0.89 vs. 1.25 ± 1.02, p = 0.0421), were observed. In both PwPMS and PwPPMS, a worsening on the Symbol Digit Modalities Test (SDMT) was associated with the reduction of fractions of white matter, cerebellum and right thalamus. SDMT performance also correlated with both gray matter fraction (GMF) and CWMF in the whole group, and with cerebellar gray matter fraction (CGMF) in PwPPMS. In PwSPMS, only Stroop Color and Word Test scores correlated with GMF and CGMF. In conclusion, subtle differences between PwPPMS and PwSPMS were detected both in MRI and neuropsychological parameters. Thus, our results indicate the need for a multicomponent attempt in characterizing progression in different clinical courses of MS.