DISRUPTION OF WHITE MATTER STRUCTURAL NETWORKS AND COGNITIVE DECLINE IN MILD COGNITIVE IMPAIRMENT

Abstract

global efficiency and microstructure of cingulum portions predict aspects of cognitive control. Results: When global efficiency was used as a sole predictor, significant relationships were found with Category Fluency (t 1⁄43.25, p 1⁄4.004), Digit Symbol Substitution (t 1⁄42.43, p 1⁄4.025), and Stroop suppression score (t 1⁄42.26, p 1⁄4.035). Category Fluency correlated most strongly with mean diffusivity (MD) of the left posterior cingulum in MCI, while MD of the left parahippocampal and right middle cingulum were the main correlates of Digit Symbol and Stroop suppression scores, respectively. When the relevant microstructural measure from a portion of the cingulum was added to any of the individual regression models for the relevant task, the relationship with global efficiency was no longer significant. In contrast, independent relationship between left posterior cingulum and Category Fluency (t 1⁄4-2.25, p 1⁄4.037) and left parahippocampal cingulum and Digit Symbol Substitution (t 1⁄4-3.30, p 1⁄4.004) remained. Conclusions:Global efficiency of white matter network structure correlates with cognitive control inMCI. Multivariate analyses suggest that alterations in global efficiency potentially mediate the effect of microstructural variation in specific components of the cingulum. However, for some tasks there was also an association between performance and microstructure of cingulum segments that was independent of global network efficiency. Both global and local network properties are likely to play a role in the status of cognitive control in MCI.