Longitudinal investigation of neuroimaging changes related to memory decline in multiple sclerosis: Testing a mechanistic model.

BACKGROUND

Memory decline is common in multiple sclerosis (MS), although pathophysiological mechanisms are not fully understood.

OBJECTIVE

The objective was to investigate the relationship of changes in structural and functional neuroimaging markers to memory decline over 3-year follow-up.

METHODS

Participants with MS underwent cognitive evaluation and structural, diffusion, and functional 3T magnetic resonance imaging (MRI) scans at baseline and 3-year follow-up. Changes in neuroimaging metrics from baseline to follow-up were compared between memory stable and memory decline groups. Our hypothesis that structural and functional connectivity changes mediate the association of atrophy to memory decline was tested.

RESULTS

A total of 249 MS patients completed baseline visit; 169 (67.8%) returned at 3-year follow-up. Based on ⩾10% decline, memory decline was observed in 44.4% (n = 75). Those with memory decline showed marginally greater whole-brain volume loss over time compared with those with stable memory performance (p = 0.08). In those with memory decline, changes in white matter tract integrity were related to regional cortical thinning (p < 0.01). Exploratory mediation analysis revealed structural and functional connectivity to mediate the relationship of atrophy to verbal and visual memory decline.

CONCLUSION

Further work is needed to characterize complex interrelationships of atrophy and structural/functional connectivity changes to memory decline in MS.