Hub brain regions for the remote spatial association between tau and Amyloid‐β proteins.

Background: The pathology of Alzheimer's disease (AD) is characterized by two types of proteins: intracellular neurofibrillary tau tangles and extracellular β‐amyloid (Aβ) plaques. In the present observational studies, spatial discrepancies between these two proteins across the brain regions are well‐documented. However, the association between these two proteins remains elusive in different stages of depositions. Methods: We aimed to investigate the remote association between tau and Aβ uptakes by using 572 elderlies 67.11 ± 6.08 (476 healthy control (HC) and 96 mild cognitive impairments (MCI)) Aβ and tau positron emission tomography (PET) scans. We leveraged 47 tau‐PET and 97 Aβ‐PET scans of healthy young individuals (aged 20‐40) to find the regional cut‐points for 68 cortical regions in the brain. Then by using these cut‐points and tau PET scans of all elderly individuals, we identified four groups of individuals (no tau phase, pre‐acceleration phase, acceleration phase, and post‐acceleration phase) (Table 1). Finally, a regional multiple linear regression model is performed for each group to detect the hubs region based on the remote association between each target region of tau and all other regions Aβ in the different phases of tau accumulations (controlling for gender, age, intracranial volume, and each target region Aβ). Results: First, we show that the left and right entorhinal cortex, and right parahippocampal tau are the hubs of remote association with Aβ in several cortical regions (especially temporal regions) in the early stage of aggregation (Figure 1). Second, we identify tau in the same regions, continuing to demonstrate the highest remote associations with cortical Aβ (Figure 2) in the acceleration phase. Conclusion: The remote association appears in medial temporal lobe (MTL) tau during the early stage, as well as the later stage of tau accumulation (pre‐acceleration and acceleration phases). While the cellular mechanism of remote association is still elusive, in vivo studies have demonstrated that the Aβ triggers tau deposition indirectly in distal regions. Understanding the association between tau and Aβ at the preclinical stage of AD is critically important for a better consideration of tau spreading, especially in disease‐related brain regions. [ABSTRACT FROM AUTHOR]