Investigate brain MRI characteristics in Multiple Sclerosis (MS) patients with functional or dysfunctional impulsivity.

Pathological Impulsivity has been described recently in Relapsing Remitting MS patients (RRMS). Dickman scale FIDI allows to distinguishing functional impulsivity (FI) which is the ability to react fast and properly when it is necessary, from dysfunctional impulsivity (DI) which is the tendency to miss forethought before acting. This study aimed to explore brain MRI characteristics in MS patients regarding abnormal lack of FI or high DI. 

Patients with Clinically Isolated Syndrome (CIS, n=16), Relapsing-Remitting MS (RRMS, n=27), Secondary Progressive MS (SPMS, n=21) and Primary Progressive MS (PPMS, n=17) were prospectively recruited at the Côte d’Azur MS clinic, and filled among extensive neuro cognitive evaluation the FIDI Dickman scale to measure FI and DI, the Fast BDI to evaluate depression and the EMIF-SEP scale to study fatigue. 3D T2-FLAIR, T1-weighted and contrast T1-weighted MRI were analyzed using automatic segmentation tools (Pixyl MS and Brain Volumetry Analysis Suite) to quantify T1 and T2 MS lesions volumes and measure the whole and regional brain atrophy.  

Throughout this cohort representing disease demyelinating spectrum and among the brain structures of interest (thalamus, amydale, precuneus, corpus callosum, insula lobe, orbito-frontal cortex and third ventricule volume), we found a strong correlation between the right thalamus atrophy and DI impulsivity (mean score of right thalamus atrophy (DS: 85.5, 272-658, p<0.0001 after Bonferrony correction). FI did not show significant association with atrophy brain volume. Taking into account the score of depression and fatigue through a multiple linear regression, only the right thalamus atrophy showed a significant impact on ID (F(2;78)=10, p<0.0001).