Can multi-modal neuroimaging evidence from hippocampus provide biomarkers for the progression of amnestic mild cognitive impairment?

Abstract

Impaired structure and function of the hippocampus is a valuable predictor of progression from amnestic mild cognitive impairment (aMCI) to Alzheimer's disease (AD). As a part of the medial temporal lobe memory system, the hippocampus is one of the brain regions affected earliest by AD neuropathology, and shows progressive degeneration as aMCI progresses to AD. Currently, no validated biomarkers can precisely predict the conversion from aMCI to AD. Therefore, there is a great need of sensitive tools for the early detection of AD progression. In this review, we summarize the specifi c structural and functional changes in the hippocampus from recent aMCI studies using neurophysiological and neuroimaging data. We suggest that a combination of advanced multi-modal neuroimaging measures in discovering biomarkers will provide more precise and sensitive measures of hippocampal changes than using only one of them. These will potentially affect early diagnosis and disease-modifying treatments. We propose a new sequential and progressive framework in which the impairment spreads from the integrity of fibers to volume and then to function in hippocampal subregions. Meanwhile, this is likely to be accompanied by progressive impairment of behavioral and neuropsychological performance in the progression of aMCI to AD.

Differential contributions of subregions of medial temporal lobe to memory system in amnestic mild cognitive impairment: insights from fMRI study

“…S1 ). Our findings suggest that MTL subregions may have a selective topography of pathological involvement in aMCI 23 30 31 32 .…”

Protective effect of APOE epsilon 2 on intrinsic functional connectivity of the entorhinal cortex is associated with better episodic memory in elderly individuals with risk factors for Alzheimer's disease

“…It is well-known that the entorhinal cortex (ERC) is one of the earliest brain regions of AD pathology [ 7 ], in concert with the hippocampus, and plays a pivotal role in the normal formation of episodic memory [ 8 ]. Recently, resting-state intrinsic functional connectivity magnetic resonance imaging (rs-fcMRI), measured by spatial synchronization of blood oxygenation level-dependent signal fluctuation, is consistently considered as a particularly useful technique not only for detecting changes in brain function that are present very early in the progression of AD but also in predicting cognitive performance [ 9 - 11 ]. Using rs-fcMRI, changes in the functional connectivity (FC) of several networks have been identified in patients with aMCI and AD [ 9 , 10 , 12 ].…”

Altered Rich-Club Organization and Regional Topology Are Associated With Cognitive Decline in Patients With Frontal and Temporal Gliomas

“…One explanation for these inconsistent findings may be that the functional and anatomical connectivities reflect different vulnerabilities, and while "functional networks" reflected changes in the "connectivity" of spatially distinct brain regions, WM structural networks delineated anatomical connectivity with deterministic tractography-derived fiber tracts (Golby et al, 2011;Javadi et al, 2017). A second reason may be that the functional and anatomical connectivities displayed nonsynchronous impairment (Chen et al, 2015). We propose that no alterations in global topology might reflect that both FTumor and TTumor patients have disrupted local brain connections when a compensatory mechanism in the global efficient information processing is employed (Xu et al, 2013).…”