Executive control deficits correlate with reduced frontal white matter volume in multiple sclerosis.

Introduction: Executive control deficits are frequently reported in patients with multiple sclerosis (MS). We have previously proposed that in the context of competing automatic and volitional processes, such deficits may in part reflect poor resolution of response conflict. This study aimed to investigate the neuropathological underpinnings of executive control deficits in MS, focusing on the frontostriatal system proposed to mediate executive control. Method: Forty-one MS patients and 25 healthy controls completed measures of executive control that have previously been used to characterize deficit in MS: antisaccade and endogenously cued saccade paradigms, and the Stroop color and word test. Relationships between task performance and volumetric measures of frontal white matter, frontal gray matter, striatum, and pallidum were investigated. Results: MS participants performed significantly more poorly on the Stroop and antisaccade tasks than controls. For MS patients, higher erroneous responding on the antisaccade task was related to reduced frontal white matter volume. Conclusion: These findings suggest that loss of frontal white matter may underlie executive control deficits in MS, and provides information that may inform the development of targeted cognitive training strategies in MS.