Dorsal hippocampal surface reduction as a biomarker of neurodegeneration in subjects with subjective cognitive decline and MCI converters to dementia

Background Hippocampal atrophy has been proposed as the main neurodegeneration marker in the Alzheimer’s disease (AD) continuum. However, scarce research has found differences on that measure at early stages, i.e. subjective cognitive decline (SCD), and between mild cognitive impairment (MCI) patien...

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Published inAlzheimer's & dementia Vol. 17; no. S4
Main Authors Verdejo, Juan, Cuesta, Pablo, Torres, Lucia, Fernández, Ricardo Bruña, Maestú, Fernando
Format Journal Article
LanguageEnglish
Published 01.12.2021
Online AccessGet full text
ISSN1552-5260
1552-5279
DOI10.1002/alz.056129

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Summary:Background Hippocampal atrophy has been proposed as the main neurodegeneration marker in the Alzheimer’s disease (AD) continuum. However, scarce research has found differences on that measure at early stages, i.e. subjective cognitive decline (SCD), and between mild cognitive impairment (MCI) patients that convert or not to AD. Here, we explored whether group differences emerged when other brain characteristics, as the white matter microstructure or the hippocampal surface shape, are used. Method The sample was composed by 393 older adults (aged from 57 to 87) recruited from the “Hospital Universitario San Carlos” and the Center for elders at the Chamartín District, all located in Madrid, Spain. They were classified in three groups according to their cognitive and functional status and following the NIA‐AA criteria: 162 were catalogued as MCI, 99 with SCD and normal cognitive performance, and 132 healthy controls without cognitive concerns. 93 of the MCI participants were followed and classified according to their clinical outcome: 31 classified as progressive MCI (p‐MCI) and 62 as stable MCI (s‐MCI). All participants underwent a MRI scan session where structural and diffusion weighted images were collected. None of the participants exhibited a history of psychiatric or neurological disorders (other than MCI). We performed tract‐based spatial statistics analysis on DTI data and vertex‐wise statistics on the structural images to explore groups differences in white matter microstructure, and hippocampal volume and surface shape. Result MCI patients exhibited reduced FA, increased MD, and reduced volume and surface of the hippocampus compared to both SCD and control groups. Differences between SCD and control groups emerged in the association between FA values and global hippocampal volume, and also in the surface shape analysis. Finally, when comparing MCI subgroups, the p‐MCI patients showed a reduced hippocampal volume and a bilateral dorsal reduction on the surface of both hippocampi compared to s‐MCI. Conclusion These results provide evidence of the progressive subcortical degeneration that occurs at different stages of healthy and pathological aging. Furthermore, they highlight the potential advantage of the use of the shape analysis of the hippocampal surface and the association between different brain measures as predictive biomarkers.
ISSN:1552-5260
1552-5279
DOI:10.1002/alz.056129