A cross-sectional and longitudinal study evaluating brain volumes, RNFL, and cognitive functions in MS patients and healthy controls

Background: The principal biomarker of neurodegeneration in multiple sclerosis (MS) is believed to be brain volume, which is associated with cognitive functions and retinal nerve fibre layer (RNFL). A cross-sectional and longitudinal assessment of the relationship between RNFL, cognitive functions and brain volume. Methods: At baseline, relapsing patients and healthy controls underwent 1.5 T MRI to estimate the normalized volume of brain (NBV), grey (NGV), white (NWV) and peripheral grey (pNGV) matter. Cognitive functions were evaluated by BICAMS, RNFL by Spectral-Domain OCT. Patients were re-evaluated after 12 months. Results: Cognitive functions, brain volume, and RNFL differed between the group of 66 patients and that of 16 healthy controls. In the MS group, at baseline, an association was found between: p-NGV and symbol-digit (SDMT) (p = 0.022); temporal-RNFL and NBV (p = 0.007), NWV (p = 0.012), NGV (p = 0.048), and p-NGV (p = 0.021); papillo-macular bundle-RNFL and NBV (p = 0.013), NWV (p = 0.02), NGV (p = 0.049), and p-NGV (p = 0.032). Over the observational period, we found a reduction of brain volume (p < 0.001), average-RNFL (p = 0.001), temporal-RNFL (p = 0.006), and papillo-macular bundle-RNFL (p = 0.009). No association was found between OCT, MRI, and cognitive changes. Conclusions: Brain volume, cognitive functions, and RNFL are continuous measures of different neurodegenerative aspects. BICAMS and OCT have low costs and can be easily used in clinical practice to monitor neurodegeneration.