Abstract
BackgroundSubjective cognitive decline (SCD) is a preclinical stage along the Alzheimer’s disease (AD) continuum. However, little is known about the aberrant patterns of connectivity and topological alterations of the brain functional connectome and their diagnostic value in SCD.MethodsResting-state functional magnetic resonance imaging and graph theory analyses were used to investigate the alterations of the functional connectome in 66 SCD individuals and 64 healthy controls (HC). Pearson correlation analysis was computed to assess the relationships among network metrics, neuropsychological performance and pathological biomarkers. Finally, we used the multiple kernel learning-support vector machine (MKL-SVM) to differentiate the SCD and HC individuals.ResultsSCD individuals showed higher nodal topological properties (including nodal strength, nodal global efficiency and nodal local efficiency) associated with amyloid-β levels and memory function than the HC, and these regions were mainly located in the default mode network (DMN). Moreover, increased local and medium-range connectivity mainly between the bilateral parahippocampal gyrus (PHG) and other DMN-related regions was found in SCD individuals compared with HC individuals. These aberrant functional network measures exhibited good classification performance in the differentiation of SCD individuals from HC individuals at an accuracy up to 79.23%.ConclusionThe findings of this study provide insight into the compensatory mechanism of the functional connectome underlying SCD. The proposed classification method highlights the potential of connectome-based metrics for the identification of the preclinical stage of AD.
Highlights
Subjective cognitive decline (SCD) is a preclinical stage along the Alzheimer’s disease (AD) continuum
We found significantly increased network strength, clustering coefficient, global efficiency and local efficiency in the SCD group compared with the healthy controls (HC) group (P < 0.05, uncorrected)
No statistical significance was observed in the hierarchy coefficient and assortativity coefficient between HC and SCD group Abbreviations: HC Health control, SCD Subjective cognitive decline *indicates a statistical difference between groups, p < 0.05 are more adoptable for the real networks and more applicable to disconnected networks [36, 37]
Summary
Subjective cognitive decline (SCD) is a preclinical stage along the Alzheimer’s disease (AD) continuum. There is presently no approved effective treatment that can stop or slow the progression of AD. It is already widely believed that the most effective treatment for AD will require intervention in the early stage of the disease, even before. Emerging evidence indicates that subjective cognitive decline (SCD), referring to selfreported cognitive decline in the absence of objective cognitive impairment, might serve as the typical preclinical stage along the AD continuum [3]. The risk for SCD individuals to convert to mild cognitive impairment (MCI) or AD is 4.5–6.5 times higher than that for normally ageing individuals [4,5,6]. A major goal is how to identify participants with SCD in an appropriate way
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