Abstract
Mild cognitive impairment is defined as greater cognitive decline than expected for a person at a particular age and is sometimes considered a stage between healthy aging and Alzheimer’s disease or other dementia syndromes. It is known that functional connectivity patterns change in people with this diagnosis. We studied functional connectivity patterns and functional segregation in a resting-state fMRI paradigm comparing 10 MCI patients and 10 healthy controls matched by education level, age and sex. Ninety ROIs from the automated anatomical labeling (AAL) atlas were selected for functional connectivity analysis. A correlation matrix was created for each group, and a third matrix with the correlation coefficient differences between the two matrices was created. Functional segregation was analyzed with the 3-cycle method, which is novel in studies of this topic. Finally, cluster analyses were also performed. Our results showed that the two correlation matrices were visually similar but had many differences related to different cognitive functions. Differences were especially apparent in the anterior default mode network (DMN), while the visual resting-state network (RSN) showed no differences between groups. Differences in connectivity patterns in the anterior DMN should be studied more extensively to fully understand its role in the differentiation of healthy aging and an MCI diagnosis.
Highlights
Mild cognitive impairment (MCI) is a syndrome in which patients have greater cognitive decline than would be expected from normal aging, but not enough to be considered dementia or another disease [1,2]
The visual network was nearly stable in both groups, and this network became the resting-state network (RSN) that seemed to be least affected by the differences between MCI and healthy adults
The results of the present study corroborate the existence of differences in functional connectivity patterns in MCI individuals when compared to the patterns in cognitively preserved adults with the same characteristics
Summary
Mild cognitive impairment (MCI) is a syndrome in which patients have greater cognitive decline than would be expected from normal aging, but not enough to be considered dementia or another disease [1,2]. Several research groups have studied this syndrome to better understand and define an MCI profile, and there have been attempts to find biomarkers for an optimal differentiation between healthy. Brain Sci. 2019, 9, 350 and MCI individuals [9,10] or to predict which patients will convert to AD or dementia [11,12,13]. Some of these studies used functional MRI (fMRI) because it is a technique that provides information about brain activation patterns by assessing blood oxygen level–dependent (BOLD) changes. Some of these studies used functional MRI (fMRI) because it is a technique that provides information about brain activation patterns by assessing blood oxygen level–dependent (BOLD) changes. fMRI is a noninvasive tool that could be used in task paradigms and in resting-state paradigms
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