A – 109 Altered Cerebellar-Frontal Connectivity in MS Patients and its Role in Processing Speed

Abstract Objective Multiple sclerosis (MS) is an autoimmune, demyelineating disease of the central nervous system. Cognitive dysfunction and processing speed decline are some of the most prominent deficits in MS. Resting-state functional connectivity demonstrates the functional organization of spatially distributed regions that comprise different cognitive networks. MS patients are also known to exhibit altered connectivity networks compared to healthy controls (HC). Previous work in healthy populations has shown that connectivity between the cerebellum and frontal areas is associated with cognitive speed. In this study, we sought to use MS as a model for cognitive dysfunction to examine the role that cerebellar-frontal connectivity may play in processing speed. Method 20 participants (10 MS, 10 HC) who met inclusion criteria underwent resting-state functional magnetic resonance (fMRI) imaging using a 3T MRI scanner. Cerebellar and frontal regions of interest (ROIs) were obtained from MPRAGE using FreeSurfer. Data were pre-processed and connectivity differences were analyzed using the CONN Toolbox. Outside of the scanner, the Digit Symbol Substitution Test (DSST) was administered as a measure of information processing speed and cognitive dysfunction. DSST performance was correlated with connectivity measures. Results MS patients exhibited higher connectivity between the cerebellum and left frontal lobe compared to HC. Furthermore, the relationship between processing speed and cerebello-frontal connectivity fundamentally differed between MS patients and HC. Conclusion These results suggest a cerebello-frontal network that is vital to processing speed, and changes to this network as a result of MS pathophysiology may contribute to the impairment of MS patients.