scholarly journals Decreased Resting-State Functional Complexity in Elderly with Subjective Cognitive Decline

Entropy ◽  
2021 ◽  
Vol 23 (12) ◽  
pp. 1591
Author(s):  
Huangjing Ni ◽  
Zijie Song ◽  
Lei Liang ◽  
Qiaowen Xing ◽  
Jiaolong Qin ◽  
...  
Keyword(s):  
Cognitive Decline ◽  
Resting State ◽  
Superior Temporal Gyrus ◽  
Blood Oxygen Level Dependent ◽  
Clinical State ◽  
Permutation Entropy ◽  
Subjective Cognitive Decline ◽  
The Novel ◽  
Nonlinear Complexity ◽  
Brain Entropy

Individuals with subjective cognitive decline (SCD) are at high risk of developing preclinical or clinical state of Alzheimer’s disease (AD). Resting state functional magnetic resonance imaging, which can indirectly reflect neuron activities by measuring the blood-oxygen-level-dependent (BOLD) signals, is promising in the early detection of SCD. This study aimed to explore whether the nonlinear complexity of BOLD signals can describe the subtle differences between SCD and normal aging, and uncover the underlying neuropsychological implications of these differences. In particular, we introduce amplitude-aware permutation entropy (AAPE) as the novel measure of brain entropy to characterize the complexity in BOLD signals in each brain region of the Brainnetome atlas. Our results demonstrate that AAPE can reflect the subtle differences between both groups, and the SCD group presented significantly decreased complexities in subregions of the superior temporal gyrus, the inferior parietal lobule, the postcentral gyrus, and the insular gyrus. Moreover, the results further reveal that lower complexity in SCD may correspond to poorer cognitive performance or even subtle cognitive impairment. Our findings demonstrated the effectiveness and sensitiveness of the novel brain entropy measured by AAPE, which may serve as the potential neuroimaging marker for exploring the subtle changes in SCD.

scholarly journals Convergent abnormalities of β-amyloid deposition, glucose metabolism, and fMRI activity in the dorsal precuneus in subjective cognitive decline

2021 ◽  
Author(s):  
Xuan-Yu Li ◽  
Li-Xia Yuan ◽  
Fei-Fan Zhou ◽  
Chang-Chang Ding ◽  
Teng-Fei Guo ◽  
...  
Keyword(s):  
Glucose Metabolism ◽  
Cognitive Decline ◽  
Resting State ◽  
Low Frequency ◽  
Development Program ◽  
Functional Brain Imaging ◽  
Subjective Cognitive Decline ◽  
Resting State Functional Connectivity ◽  
Positron Emission ◽  
Β Amyloid

Background: There has been no report on convergent local abnormalities of multiple functional brain imaging modalities including β-amyloid (Aβ) deposition, glucose metabolism, and resting-state functional magnetic resonance imaging (RS-fMRI) activities for participants with subjective cognitive decline (SCD). Methods: Fifty participants with SCD and 15 normal controls (NC) were scanned with both [18F]-florbetapir positron emission tomography (PET) and [18F]-fluorodeoxyglucose PET, each PET sacn accompanied with simultaneous RS-fMRI. Voxel-wise metrics were analyzed, including Aβ deposition, glucose metabolism, and three local metrics for RS-fMRI, i.e., amplitude of low frequency fluctuation (ALFF), regional homogeneity (ReHo), and degree centrality (DC). Results: The SCD group showed increased Aβ deposition and increased glucose metabolism (P < 0.05, corrected), as well as decreased ALFF, ReHo, and DC (P < 0.05, uncorrected) in the same area of the left dorsal precuneus (dPCu). The dPCu showed negative resting state functional connectivity (RSFC) with the default mode network (DMN). Regarding global Aβ deposition positivity, the Aβ deposition in the dPCu showed a gradient change, i.e., SCD+ > SCD- > NC-. Further, both SCD+ and SCD- showed increased glucose metabolism and decreased RS-fMRI metrics in the dPCu. Conclusions: The convergent abnormal activities in the dPCu of SCD indicate that the dPCu is an early vulnerable region. The anti-RSFC of the dPCu with DMN supports that the earliest symptoms might be more related to other cognitive functions (e.g., unfocused attention) than episodic memory. (Funded by the National Key Research and Development Program of China and others; ClinicalTrials.gov number, NCT03370744.)

Impaired cerebral vascular and metabolic responses to parametric N-back tasks in subjective cognitive decline

2021 ◽  
pp. 0271678X2110121
Author(s):  
Yaoyu Zhang ◽  
Wenying Du ◽  
Yayan Yin ◽  
Huanjie Li ◽  
Zhaowei Liu ◽  
...  
Keyword(s):  
Cognitive Decline ◽  
Frontal Lobe ◽  
Cognitive Processing ◽  
Cerebral Blood Volume ◽  
Parietal Lobe ◽  
Blood Oxygen Level Dependent ◽  
Metabolic Responses ◽  
Subjective Cognitive Decline ◽  
Control Subjects ◽  
Mri Scans

Previous studies reported abnormally increased and/or decreased blood oxygen level-dependent (BOLD) activations during functional tasks in subjective cognitive decline (SCD). The neurophysiological basis underlying these functional aberrations remains debated. This study aims to investigate vascular and metabolic responses and their dependence on cognitive processing loads during functional tasks in SCD. Twenty-one SCD and 18 control subjects performed parametric N-back working-memory tasks during MRI scans. Task-evoked percentage changes (denoted as δ) in cerebral blood volume (δCBV), cerebral blood flow (δCBF), BOLD signal (δBOLD) and cerebral metabolic rate of oxygen (δCMRO2) were evaluated. In the frontal lobe, trends of decreased δCBV, δCBF and δCMRO2 and increased δBOLD were observed in SCD compared with control subjects under lower loads, and these trends increased to significant differences under the 3-back load. δCBF was significantly correlated with δCMRO2 in controls, but not in SCD subjects. As N-back loads increased, the differences between SCD and control subjects in δCBF and δCMRO2 tended to enlarge. In the parietal lobe, no significant between-group difference was observed. Our findings suggested that impaired vascular and metabolic responses to functional tasks occurred in the frontal lobe of SCD, which contributed to unusual BOLD hyperactivation and was modulated by cognitive processing loads.

scholarly journals Resting-state functional reorganisation in Alzheimer’s disease and amnestic mild cognitive impairment: protocol for a systematic review and meta-analysis

BMJ Open ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. e049798
Author(s):  
Diyang Lyu ◽  
Taoran Li ◽  
Xuanxin Lyu
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Cognitive Impairment ◽  
Mild Cognitive Impairment ◽  
Cognitive Decline ◽  
Resting State ◽  
Assessment Tool ◽  
Brain Regions ◽  
Amnestic Mild Cognitive Impairment ◽  
Subjective Cognitive Decline

IntroductionThe incidence of Alzheimer’s disease (AD) is increasing rapidly, causing a growing burden to health and economic worldwide. Several clinical trials in the past decade failed to find solutions, and there remains a lack of an effective treatment. The evidence suggests that early intervention for neurodegeneration would likely be effective in preventing cognitive decline. Cognitive decline in AD occurs continuously over a long period; however, there remains a lack of simple, rapid and accurate approach for diagnosis of amnestic mild cognitive impairment or subjective cognitive decline due to underlying Alzheimer’s pathology. Resting-state functional MRI (rs-fMRI) determines the functional activities of the human brain non-invasively. The amplitude of low-frequency fluctuation (ALFF), fractional ALFF (fALFF) and regional homogeneity (ReHo) are rs-fMRI indicators with high repeatability. They have been studied as early diagnostic imaging markers for other diseases and may be promising markers also for AD.Methods and analysisThe following electronic literature databases will be searched from inception to December 2021: Medline-Ovid, Medline-PubMed, EMBase-Ovid, Cochrane Central and ClinicalTrials.gov. Two independent reviewers will select studies with eligible criteria, extract data and assess the quality of the original studies with our quality assessment tool individually. Missing data will be requested by sending emails to the corresponding authors. Brain regions will be presented for ALFF/fALFF and ReHo by performing activation likelihood estimation with the Seed-based d Mapping-Permutation of subject images V.6.21 software. Meta-regression will be performed to determine the potential brain regions that may strongly correlate with cognitive decline progression. Subgroup analysis, funnel plot, Egger’s test and sensitivity analysis will be conducted to detect and explain potential heterogeneity.Ethics and disseminationThis study does not require formal ethical approval. The findings will be submitted to a peer-review journal.PROSPERO registration numberCRD42021229009.

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