Abstract
Despite subjective cognitive decline (SCD), a preclinical stage of Alzheimer's disease (AD), being widely studied in recent years, studies on centrality frequency in individuals with SCD are lacking. This study aimed to investigate the differences in centrality frequency between individuals with SCD and normal controls (NCs). Forty individuals with SCD and 53 well-matched NCs underwent a resting-state functional magnetic resonance imaging scan. We assessed individual dynamic functional connectivity using sliding window correlations. In each time window, brain regions with a high degree centrality were defined as hubs. Across the entire time window, the proportion of time that the hub appeared was characterized as centrality frequency. The centrality frequency correlated with cognitive performance differently in individuals with SCD and NCs. Our results revealed that in individuals with SCD, compared with NCs, correlations between centrality frequency of the anterior cortical regions and cognitive performance decreased (79.2% for NCs and 43.5% for individuals with SCD). In contrast, correlations between centrality frequency of the posterior cortical regions and cognitive performance increased in SCD individuals compared with NCs (20.8% for NCs and 56.5% for individuals with SCD). Moreover, the changes mainly focused on the anterior (93.3% for NCs and 45.5% for individuals with SCD) and posterior (6.7% for NCs and 54.5% for individuals with SCD) regions associated with the default mode network (DMN). In addition, we used absolute thresholds (correlation efficient r = 0.2, 0.25) and proportional thresholds (sparsity = 0.2, 0.25) to verify the results. Dynamic results are relative stable at absolute thresholds while static results are relative stable at proportional thresholds. Converging findings provide a new framework for the detection of the changes occurring in individuals with SCD via centrality frequency of the DMN.
Highlights
Alzheimer’s disease (AD) is one of the classical chronic neurodegenerative diseases and considered of the common cause of dementia
We considered that these brain regions contributed more prominently to cognitive performance
We classified these brain regions into the anterior region, posterior region and subcortical region. 79.2% of the brain regions we found in the normal controls (NCs) group were located in anterior cortical regions, including the bilateral superior frontal gyrus,bilateral middle frontal gyrus, orbital part, left opercular part of inferior frontal gyrus, left supplementary motor area, left olfactory cortex, bilateral superior frontal gyrus, FIGURE 3 | Relationship between hub probability measured by dynamic functional connectivity of brain regions and neuropsychological tests in NC group, subjective cognitive decline (SCD) group and all participants
Summary
Alzheimer’s disease (AD) is one of the classical chronic neurodegenerative diseases and considered of the common cause of dementia. There are no effective treatments that can stop or slow AD progression by much (Winblad et al, 2016), so developed countries have spent a great deal on AD patients’ medical care. SCD generally refers to subjectively experienced cognitive deterioration (Tales et al, 2015) and primarily related to the increasing risk of developing AD (Jessen et al, 2014). Researchers found a disrupted pattern in the peripheral brain regions of SCD subjects based on the structural diffusion tensor imaging data (Yan et al, 2018). Previous studies have shown abnormal increased brain activity during memory tasks in MCI (Puregger et al, 2003) and SCD (Maestu et al, 2011) subjects. The above studies mainly adopted the method of magnetoencephalogram (MEG) or electroencephalogram (EEG) because of its high temporal resolution
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