Brain connectivity changes in patients with working memory impairments with chronic ischemic cerebrovascular disease

Abstract

One of the methods of assessment of cognitive functions in patients with chronic ischemic cerebrovascular disease — CICD (dyscirculatory encephalopathy) implies studying connectivity of neural networks through the analysis of rest functional magnetic resonance imaging (rest fMRI) data. The main objective of this study was to assess the relationship between working memory (WM) characteristics and connectivity of various parts of the brain in patients diagnosed with CICD. The study involved 22 female CICD patients; they were divided into two groups, one with satisfactory level of WM and the other with compromised WM. We assessed intra-brain connectivity with the help of rest fMRI, using the SPM-12 and CONN18b software applications in Matlab platform. The other aspects evaluated were the gray to white matter ratio and the association of this indicator with WM. Significant differences in the intra-brain connectivity were registered in both the satisfactory WM group and the compromised WM group. The brain parts where those differences were found are left parahippocampal area and right supramarginal gyrus; right cerebellar hemisphere and left parietal, as well as left frontal areas; right cingular and left lingual gyri. In addition, we detected significant differences in the ratio in the gray and white matter volumes in both groups (p = 0.007). The results obtained indicate that memory deterioration in CICD patients is concomitant with deteriorating connectivity between the cortical areas, as well as between cerebellum and cortex, which may be associated with a more significant loss of the white matter.