Comparing short-term memory, working memory and executive functions among patients with relapsing remitting multiple sclerosis and healthy individuals

Abstract

Objective: The intrinsic connectivity networks mostly affected in Alzheimer’s disease (AD) are the default mode (DMN) and salience networks (SN). The capacity of the functional connectivity (FC) changes in these networks in differentiating subjective cognitive impairment (SCI), earliest stage of cognitive decline along the AD continuum, from objectively diagnosed mild cognitive impairment (MCI) is not yet shown. Therefore, we investigated FC changes in DMN and SN among SCI, MCI and AD dementia (ADD) groups. Methods: Resting-state fMRI data of 88 participants (21 ADD, 34 MCI, 33 SCI) were collected with 3T MRI scanner. FC of 11 regions of interest (ROI) corresponding to DMN and SN nodes were analysed using CONN-toolbox (https://web.conn-toolbox.org/). Cluster level significance threshold in the F test among the 3 groups was set at p(FWE-corr) <0.0045 (Bonferroni corrected according to number of ROIs). For ROIs with significant difference in the F test, t-tests were performed between pairs of groups, and results with p(FWE-corr) <0.017 were reported. Results: In ADD compared to both MCI and SCI, FC of posterior cingulate cortex node of DMN with temporal and occipital cortices, FC of anterior cingulate cortex (ACC) node of SN with right insula and temporal cortices and FC of right and left anterior insula nodes of SN with ACC significantly decreased. Additionally, for ADD vs MCI comparison, FC of left anterior insula node of SN with the right insula, and for ADD vs SCI comparison, FC of the right and left anterior insula nodes of SN with the supplementary motor area were reduced. Conclusion: The findings reveal that the FC changes of DMN and SN in AD continuum occur in the advanced stages of the disease with no distinctive change between SCI and MCI stages.