title: Transverse diffusivity of cerebral parenchyma predicts visual tracking performance in relapsing-remitting multiple sclerosis.
abstract: This study investigated the relation between cerebral damage related to multiple sclerosis (MS) and cognitive decline as determined by two classical mental tracking tests. Cerebral damage in 15 relapsing-remitting MS patients was measured by diffusion tensor imaging (DTI). Fractional anisotropy, longitudinal and transverse diffusivity were defined in the cerebral parenchyma. Cognitive performance of the MS patients was assessed with the oral response format of the Symbol Digit Modalities Test (SDMT) and the Paced Auditory Serial Addition Test (PASAT). A significant correlation was found between performance on the SDMT and the fractional anisotropy in the brain. This correlation was predominantly induced by transverse diffusivity. Transverse diffusivity refers to the diffusion across fibers rather than along the fibers and is believed to be a specific marker for axonal loss and demyelination associated with MS. No significant association between DTI-measures and PASAT performance was found and this negative finding was mainly attributed to psychometric qualities. These results indicate that diffusivity along the non-principal diffusion direction, a possible signature of MS-related white matter pathology, contributes to information processing speed as measured with the SDMT, a task that requires close visual tracking and a widely used clinical marker for cognitive decline in MS.
authors: Laboratory for Neuropsychology, Department of Neurology, Ghent University, De Pintelaan 185-4K3, B-9000 Ghent, Belgium. nele.warlop@ugent.be
authors: Nele P
authors: NP
authors: Warlop
authors: Eric
authors: E
authors: Achten
authors: Els
authors: E
authors: Fieremans
authors: Jan
authors: J
authors: Debruyne
authors: Guy
authors: G
authors: Vingerhoets
mesh_terms: D000328:Adult; D016880:Anisotropy; D001307:Auditory Perception / Q000502:physiology; D001369:Axons / Q000473:pathology; D002540:Cerebral Cortex / Q000473:pathology* / Q000503:physiopathology; D003071:Cognition / Q000502:physiology; D056324:Diffusion Tensor Imaging; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000473:pathology / Q000503:physiopathology*; D009483:Neuropsychological Tests; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology