The fractional amplitude of low-frequency fluctuations signals related to amyloid uptake in high-risk populations-A pilot fMRI study

Yi-Wen Bao; Yat-Fung Shea; Patrick Ka-Chun Chiu; Joseph S K Kwan; Felix Hon-Wai Chan; Wing-Sun Chow; Koon-Ho Chan; Henry Ka-Fung Mak

doi:10.3389/fnagi.2022.956222

The fractional amplitude of low-frequency fluctuations signals related to amyloid uptake in high-risk populations-A pilot fMRI study

Front Aging Neurosci. 2022 Jul 29:14:956222. doi: 10.3389/fnagi.2022.956222. eCollection 2022.

Authors

Yi-Wen Bao¹, Yat-Fung Shea², Patrick Ka-Chun Chiu², Joseph S K Kwan², Felix Hon-Wai Chan², Wing-Sun Chow², Koon-Ho Chan², Henry Ka-Fung Mak¹

Affiliations

¹ Department of Diagnostic Radiology, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong, Hong Kong SAR, China.
² Department of Medicine, Queen Mary Hospital, Hong Kong, Hong Kong SAR, China.

Abstract

Background: Patients with type 2 diabetes mellitus (T2DM) and subjective cognitive decline (SCD) have a higher risk to develop Alzheimer's Disease (AD). Resting-state-functional magnetic resonance imaging (rs-fMRI) was used to document neurological involvement in the two groups from the aspect of brain dysfunction. Accumulation of amyloid-β (Aβ) starts decades ago before the onset of clinical symptoms and may already have been associated with brain function in high-risk populations. However, this study aims to compare the patterns of fractional amplitude of low-frequency fluctuations (fALFF) maps between cognitively normal high-risk groups (SCD and T2DM) and healthy elderly and evaluate the association between regional amyloid deposition and local fALFF signals in certain cortical regions.

Materials and methods: A total of 18 T2DM, 11 SCD, and 18 healthy elderlies were included in this study. The differences in the fALFF maps were compared between HC and high-risk groups. Regional amyloid deposition and local fALFF signals were obtained and further correlated in two high-risk groups.

Results: Compared to HC, the altered fALFF signals of regions were shown in SCD such as the left posterior cerebellum, left putamen, and cingulate gyrus. The T2DM group illustrated altered neural activity in the superior temporal gyrus, supplementary motor area, and precentral gyrus. The correlation between fALFF signals and amyloid deposition was negative in the left anterior cingulate cortex for both groups. In the T2DM group, a positive correlation was shown in the right occipital lobe and left mesial temporal lobe.

Conclusion: The altered fALFF signals were demonstrated in high-risk groups compared to HC. Very early amyloid deposition in SCD and T2DM groups was observed to affect the neural activity mainly involved in the default mode network (DMN).

Keywords: Alzheimer's Disease; amyloid; functional MRI; neural activity; subjective cognitive decline; type 2 diabetes mellitus.