Cognitive impairment in relapsing—remitting multiple sclerosis can be predicted by imaging performed several years earlier

Abstract

Cognitive deficits in multiple sclerosis (MS) are common and correlate with contemporary MRI brain abnormalities, particularly atrophy, but the ability of imaging early in the disease to predict later cognitive impairment remains to be determined. Thirty relapsing-remitting MS patients recruited within three years of the onset of the disease, and in whom MRI had been performed at baseline and a year later, were assessed neuropsychologically five years later. Imaging parameters accounting for significant variance in cognitive performance were identified using multiple regressions, once confounding variables were controlled. Patients performed significantly worse than expected on tests of attention/speed of information processing and half of them had experienced some decline in IQ in relation to premorbid estimates. The rate of global brain atrophy in the first year of the study accounted for significant variance in the overall cognitive performance, and in memory and attention/speed of information processing. Poor performance on attention tests was associated with high T1-weighted lesion volume and reduced magnetization transfer ratio (MTR) in normal-appearing white matter (NAWM). These results suggest that neuroaxonal loss was identified early in the disease, and its rate of progression, predicted cognitive impairment later in the disease. Neuroaxonal loss is likely to affect commissural and association fibres that subserve the cognitive processes impaired in MS.

Stroop performance in multiple sclerosis: Information processing, selective attention, or executive functioning?

“…Rate of progression of neuroaxonal loss, likely to affect commissural and association fibers that subserve attention and information processing speed, has been shown to correlate with cognitive decline in MS (Summers et al, 2008). Future research might usefully compare the relative lesion load in frontal-subcortical pathways and interhemispheric commissures in patients with MS who have only information processing speed impairment against those who have additional genuine executive functioning impairment.…”

Pathology and MRI: exploring cognitive impairment in MS

“…56,57 In contrast, change of T2 lesion volume over time appeared to be a less relevant contributor to cognitive decline in RRMS. 56,58 However, in a recent study in PPMS patients, T2 lesions best predicted cognitive impairment after 5 years, 59 and newly occurring or enlarging T2 lesions in the left anterior cerebellum, the thalami, the corpus callosum, the right gyrus frontalis inferior and superior, and the deep white matter of the left frontal lobe predicted cognitive worsening after 5 years.…”

The contribution of MRI in assessing cognitive impairment in multiple sclerosis

“…Using a voxel-based method, significant correlations were found between decrease of MTR value in specific cortical regions and PASAT performance in patients with primary progressive MS. 27 In addition, global MTR changes of the NAWM at illness onset predicted impairment in executive function in patients with RRMS when cognitively examined several years later. 28 Molecular diffusion in brain tissue can be measured in vivo using DT MRI. As WM tracts of the brain have an orientated microstructure, diffusion is easier along rather than across these tracts, a process known as anisotropy.…”