Abstract
BackgroundSubjective cognitive decline (SCD) and amnestic mild cognitive impairment (aMCI) were considered to be a continuum of Alzheimer’s disease (AD) spectrum. The abnormal topological architecture and rich-club organization in the brain functional network can reveal the pathology of the AD spectrum. However, few studies have explored the disrupted patterns of diverse club organizations and the combination of rich- and diverse-club organizations in SCD and aMCI.MethodsWe collected resting-state functional magnetic resonance imaging data of 19 SCDs, 29 aMCIs, and 28 healthy controls (HCs) from the Alzheimer’s Disease Neuroimaging Initiative. Graph theory analysis was used to analyze the network metrics and rich- and diverse-club organizations simultaneously.ResultsCompared with HC, the aMCI group showed altered small-world and network efficiency, whereas the SCD group remained relatively stable. The aMCI group showed reduced rich-club connectivity compared with the HC. In addition, the aMCI group showed significantly increased feeder connectivity and decreased local connectivity of the diverse club compared with the SCD group. The overlapping nodes of the rich club and diverse club showed a significant difference in nodal efficiency and shortest path length (Lp) between groups. Notably, the Lp values of overlapping nodes in the SCD and aMCI groups were significantly associated with episodic memory.ConclusionThe present study demonstrates that the network properties of SCD and aMCI have varying degrees of damage. The combination of the rich club and the diverse club can provide a novel insight into the pathological mechanism of the AD spectrum. The altered patterns in overlapping nodes might be potential biomarkers in the diagnosis of the AD spectrum.
Highlights
Subjective cognitive decline (SCD) refers to memory complaints subjectively with a normal performance at objective neurocognitive assessments (Jessen et al, 2014a,b)
The SCD and amnestic mild cognitive impairment (aMCI) groups exhibited significantly higher scores in Geriatric Depression Scale (GDS) compared with the healthy controls (HCs)
The results showed that the aMCI group showed a significantly decreased volume of the bilateral hippocampus compared with the HC and SCD after controlling the effects of age and sex (Bonferronicorrected, p < 0.05)
Summary
Subjective cognitive decline (SCD) refers to memory complaints subjectively with a normal performance at objective neurocognitive assessments (Jessen et al, 2014a,b). SCD is considered to be an earlier stage of amnestic mild cognitive impairment (aMCI) and has a high predictive value for Alzheimer’s disease (AD) (Slot et al, 2019). Some population-based prospective studies showed that patients with aMCI have a higher risk of developing AD. This might mean that SCD and aMCI could be regarded to be preclinical AD spectrum and may have distinct pathological characteristics in different stages of the AD spectrum (Xue et al, 2019). Comparing and analyzing the neuroimaging characteristics of SCD and aMCI may allow deep-going prediction of the disease development and give insight into mechanisms of AD spectrum-related cognitive dysfunction. Few studies have explored the disrupted patterns of diverse club organizations and the combination of rich- and diverse-club organizations in SCD and aMCI
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