Amyloid-related changes of basal forebrain volume and precuneus functional connectivity in Subjective Cognitive Decline patients

2020 ◽  
Author(s):  
M Daamen ◽  
S Li ◽  
L Scheef ◽  
F Gärtner ◽  
H Amthauer ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Cognitive Decline ◽  
Basal Forebrain ◽  
Subjective Cognitive Decline

scholarly journals Recurrent and Concurrent Patterns of Regional BOLD Dynamics and Functional Connectivity Dynamics in Cognitive Decline

2020 ◽  
Author(s):  
Lingyan Liang ◽  
Yueming Yuan ◽  
Yichen Wei ◽  
Bihan Yu ◽  
Wei Mai ◽  
...  
Keyword(s):  
Functional Connectivity ◽  
Cognitive Decline ◽  
Low Frequency ◽  
Occurrence Frequency ◽  
Subjective Cognitive Decline ◽  
Imaging Data ◽  
Dynamic Features ◽  
Spontaneous Neural Activity ◽  
Neuroimaging Biomarkers ◽  
Brain States

Abstract Background : The brain’s dynamic spontaneous neural activity and dynamic functional connectivity (dFC) are both important in supporting cognition, but how these two types of brain dynamics evolve and co-evolve in subjective cognitive decline (SCD) and mild cognitive impairment (MCI) remain unclear. The aim of the present study was to investigate recurrent and concurrent patterns of two types of dynamic brain states correlated with cognitive decline.Methods : The present study analyzed resting-state functional magnetic resonance imaging data from 62 SCD patients, 75 MCI patients, and 70 healthy controls (HCs). We used the sliding-window and clustering method to identify two types of recurrent brain states from both dFC and dynamic regional spontaneous activity, as measured by dynamic fractional amplitude of low-frequency fluctuations (dfALFF). Then, the occurrence frequency of a dFC or dfALFF state and the co-occurrence frequency of a pair of dFC and dfALFF states among all time points are extracted for each participant to describe their dynamics brain patterns.Results : We identified a few recurrent states of dfALFF and dFC, and further ascertained the co-occurrent patterns of these two types of dynamic brain states (i.e., dfALFF and dFC states). Importantly, the occurrence frequency of a default-mode network (DMN)-dominated dFC state was significantly different between HCs and SCD patients, and the co-occurrence frequencies of a DMN-dominated dFC state and a DMN-dominated dfALFF state were also significantly different between SCD and MCI patients. These two dynamic features were both significantly positively correlated with Mini Mental State Examination scores.Conclusion : Our findings revealed novel fMRI-based neural signatures of cognitive decline from recurrent and concurrent patterns of dfALFF and dFC, providing strong evidence supporting SCD as the transition phase between normal aging and MCI. This finding holds potential to differentiate SCD patients from HCs via both dFC and dfALFF as objective neuroimaging biomarkers, which may aid in the early diagnosis and intervention of Alzheimer’s disease.

scholarly journals Alterations in Dynamic Functional Connectivity in Individuals With Subjective Cognitive Decline

2021 ◽  
Vol 13 ◽  
Author(s):  
Qian Chen ◽  
Jiaming Lu ◽  
Xin Zhang ◽  
Yi Sun ◽  
Wenqian Chen ◽  
...  
Keyword(s):  
Graph Theory ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Cognitive Performance ◽  
Dwell Time ◽  
Subjective Cognitive Decline ◽  
Control Group ◽  
Dynamic Functional Connectivity ◽  
Neuropsychological Evaluations ◽  
Window Approach

Purpose: To investigate the dynamic functional connectivity (DFC) and static parameters of graph theory in individuals with subjective cognitive decline (SCD) and the associations of DFC and topological properties with cognitive performance.Methods: Thirty-three control subjects and 32 SCD individuals were enrolled in this study, and neuropsychological evaluations and resting-state functional magnetic resonance imaging scanning were performed. Thirty-three components were selected by group independent component analysis to construct 7 functional networks. Based on the sliding window approach and k-means clustering, distinct DFC states were identified. We calculated the temporal properties of fractional windows in each state, the mean dwell time in each state, and the number of transitions between each pair of DFC states. The global and local static parameters were assessed by graph theory analysis. The differences in DFC and topological metrics, and the associations of the altered neuroimaging measures with cognitive performance were assessed.Results: The whole cohort demonstrated 4 distinct connectivity states. Compared to the control group, the SCD group showed increased fractional windows and an increased mean dwell time in state 4, characterized by hypoconnectivity both within and between networks. The SCD group also showed decreased fractional windows and a decreased mean dwell time in state 2, dominated by hyperconnectivity within and between the auditory, visual and somatomotor networks. The number of transitions between state 1 and state 2, between state 2 and state 3, and between state 2 and state 4 was significantly reduced in the SCD group compared to the control group. No significant differences in global or local topological metrics were observed. The altered DFC properties showed significant correlations with cognitive performance.Conclusion: Our findings indicated DFC network reconfiguration in the SCD stage, which may underlie the early cognitive decline in SCD subjects and serve as sensitive neuroimaging biomarkers for the preclinical detection of individuals with incipient Alzheimer's disease.

scholarly journals Decreased Dynamic Flexibility of Brain Functional Connectivity in Prodromal Alzheimer’s Disease

2018 ◽  
Vol 1 (1) ◽  
Author(s):  
Zachary G. Osborn ◽  
Shannon L. Risacher ◽  
John D. West ◽  
Eileen Tallman ◽  
Liana Apostolova ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Functional Mri ◽  
Information Transfer ◽  
Time Windows ◽  
Parahippocampal Gyrus ◽  
Subjective Cognitive Decline ◽  
Functional Flexibility

Background and Hypothesis:  In neuroimaging, functional connectivity (FC), defined as the correlation between the functional MRI signals of two brain grey matter regions of interest (ROIs), is thought to reflect communication between ROIs. Changes in whole brain FC networks have been detected in Alzheimer’s disease (AD); however, traditional FC networks generated using the entire length of an fMRI scan could miss cognitively relevant fluctuations in FC. Analyzing dynamic patterns of FC within subsets of fMRI scans is hypothesized to enable greater sensitivity to deficits of information transfer and processing in AD compared to static FC.  Project Methods:  Functional MRI data of 58 participants with either subjective cognitive decline (SCD), mild cognitive impairment (MCI), AD, or controls were divided into time windows; the FC within each window provides sequential dynamic FC networks (dFC). Each dFC network was partitioned into subnetworks, e.g. visual or motor, whose member ROIs are strongly interconnected, and the functional flexibility of an ROI was estimated by the number of times it switches subnetworks in a scan.  Results:  The flexibility of the left inferior parietal lobule, right rostral lateral orbitofrontal cortex, and right amyglada/parahippocampal gyrus showed the highest correlations with Montreal Cognitive Assessment scores: r = 0.2516, 0.2480, and 2421, respectively. Although no correlations reached conventional significance (p = 0.0568, 0.0605, and 0.0671, uncorrected), this may reflect low power that should be increased with a planned larger sample.  Potential Impact:  Dynamic FC analyses may help clarify the neurophysiological mechanisms underlying cognitive decline, but methodological refinements and higher resolution data are likely needed to realize this potential.

Identification of Earlier Biomarkers for Alzheimer’s Disease: A Multimodal Neuroimaging Study of Individuals with Subjective Cognitive Decline

2020 ◽  
Vol 77 (3) ◽  
pp. 1067-1076
Author(s):  
Ashleigh F. Parker ◽  
Colette M. Smart ◽  
Vanessa Scarapicchia ◽  
Jodie R. Gawryluk ◽  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Functional Connectivity ◽  
Cognitive Decline ◽  
Functional Mri ◽  
Healthy Aging ◽  
Angular Gyrus ◽  
Subjective Cognitive Decline ◽  
Grey Matter Volume ◽  
Increased Risk

Background: Individuals with subjective cognitive decline (SCD) are thought to be the earliest along the cognitive continuum between healthy aging and Alzheimer’s disease (AD). Objective: The current study used a multi-modal neuroimaging approach to examine differences in brain structure and function between individuals with SCD and healthy controls (HC). Methods: 3T high-resolution anatomical images and resting-state functional MRI scans were retrieved for 23 individuals with SCD and 23 HC from the Alzheimer’s Disease Neuroimaging Initiative (ADNI) database. Results: The SCD and HC groups were not significantly different in age or education level. Voxel-based morphometry results did not show significant differences in grey matter volume between the groups. Functional MRI results revealed significantly greater functional connectivity in the default mode network in regions including the bilateral precuneus cortex, bilateral thalamus, and right hippocampal regions in individuals with SCD relative to controls. Conversely, those with SCD showed decreased functional connectivity in the bilateral frontal pole, caudate, angular gyrus, and lingual gyrus, compared to HC. Conclusion: Findings revealed differences in brain function but not structure between individuals with SCD and HC. Overall, this study represents a crucial step in characterizing individuals with SCD, a group recognized to be at increased risk for AD. It is imperative to identify biomarkers of AD prior to significant decline on clinical assessment, so that disease-delaying interventions may be delivered at the earliest possible time point.

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