Abstract
Patients with amnestic mild cognitive impairment (aMCI) are at high risk of developing dementia. This study used resting-state functional magnetic resonance imaging (rs-fMRI) and an independent component analysis (ICA) approach to explore changes in functional connectivity (FC) in the default mode network (DMN), executive control network (ECN), and salience network (SN). Thirty patients with aMCI and 30 healthy controls (HCs) were enrolled. All the participants underwent an rs-fMRI scan. The brain FC in DMN, ECN, and SN was calculated using the ICA approach. We found that the FC of brain regions in DMN decreased significantly and that of brain regions in ECN increased, which was in accordance with the findings of previous studies on Alzheimer's disease (AD) and aMCI. We also found that the FC of brain regions in SN increased, which was different from the findings of previous studies on AD. The increase in FC in brain regions in SN might result from different pathophysiological states in AD and aMCI, indicating that a decrease in FC in SN does not occur in a person with aMCI. These results are consistent with those of previous studies using the voxel-mirrored homotopic connectivity approach and seed-based correlation analysis. We therefore considered that the decrease in FC in DMN and the increase in FC in ECN and SN might be peculiar patterns observed on the rs-fMRI of a person with aMCI. These findings may contribute to the development of imaging biomarkers for the diagnosis of aMCI.
Highlights
Mild cognitive impairment (MCI) is a pathological state between normal cognition and dementia
Patients meeting the following criteria were included in the amnestic MCI (aMCI) group: [1] those with cognitive impairment, which refers to memory impairment and other cognitive domain damage reported by the patient or the informed person and confirmed via objective examination; [2] those whose basic daily abilities were not affected and whose complex instrumental daily ability was only slightly damaged; [3] those who did not meet the diagnostic criteria for dementia; and [4] those with a geriatric depression scale score of 2–3, a memory test score 1.5 times lower than the standard deviation of the control group matched by age and education, a mini-mental state examination (MMSE) score ≥ 24, and a Hachinski Ischemic Score (HIS) ≤ 4
We found that the significant decrease in functional connectivity (FC) in brain regions can be attributed to default mode network (DMN) and the increase in FC in brain regions can be attributed to executive control network (ECN); these findings are in accordance with previous studies on Alzheimer’s disease (AD) and MCI
Summary
Mild cognitive impairment (MCI) is a pathological state between normal cognition and dementia. The annual conversion rate from MCI to dementia is reportedly ∼10–15%, which is 10 times that in the normal population [1]. MCI has been regarded as a crucial stage in which the long-term outcome of dementia may be improved if early diagnosis and intervention. AMCI manifests predominantly as memory loss and is more likely to progress to Alzheimer’s disease (AD), whereas naMCI is closely associated with forms of dementia other than AD [3]. Because AD is a leading neurodegenerative disease, the relationship between aMCI and AD and the early diagnosis and treatment of aMCI have garnered much attention from clinicians
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