High‑Resolution T2 MRI Volumetry of Medial Temporal Lobe Subregions Predicts Cognitive Decline Across the Alzheimer's
Mehrdad Mozafar1, Sahba Shahbazi2,3, Mohammad Amir Amirian4
1School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
Abstract:
Atrophy of medial temporal lobe (MTL) subregions is an early biomarker of Alzheimer's disease (AD). This study aimed to examine the relationship between MTL subregion volumes and cognitive performance in patients across the AD continuum. We analyzed data from 276 participants using the Alzheimer's Disease Neuroimaging Initiative (ADNI), including 74 cognitively normal (CN), 110 subjective memory complaints (SMC), 37 early mild cognitive impairment (EMCI), 35 late mild cognitive impairment (LMCI), and 20 AD participants. MTL subregions volumes were measusing high-resolution T2-weighted MRI, and analyses were adjusted for age, education, APOE ε4 status, and intracranial volume (ICV). Significant atrophy in regions such as the cornu ammonis (CA), dentate gyrus (DG), subiculum (SUB), entorhinal cortex (ERC), and Brodmann area 35 (BA35) was found in AD participants compared with other groups. In AD, poorer Alzheimer's Disease Assessment Scale - Cognitive Subscale 13 (ADAS-13) performance was associated with reduced CA, DG, BA35, and parahippocampal cortex (PHC) volumes. In LMCI, lower Mini-Mental State Examination (MMSE) scores were associated with atrophy in CA and SUB. Diminished Montreal Cognitive Assessment (MoCA) scores were linked to reduced ERC volumes in CN, as well as with atrophy in BA35, ERC and CA subfields among AD patients. In LMCI, poorer Trail Making Test, Part B performance (i.e., longer completion time) was related to smaller Brodmann area 36 (BA36), collateral sulcus (CS), and PHC subregion volumes, whereas in the AD, it was related to BA36 only. Poorer immediate memory recall in AD was associated with atrophy in CA, DG, while in early stages of MCI, poorer verbal learning scores correlated with atrophy in the CA, DG, BA35, SUB, and CS regions. Moreover, diminished Logical Memory Delayed Recall was associated with atrophy in the CA, BA35, and PHC subfields among AD subjects. These findings support the value of atrophy in MTL subregions as potential imaging markers for detecting and monitoring cognitive decline across the AD continuum.
Insights
Medial temporal lobe (MTL) atrophy, particularly in regions like the hippocampus and entorhinal cortex, is linked to cognitive decline across Alzheimer's disease (AD) stages. These brain volume changes serve as key imaging markers for monitoring AD progression.
Area of Science:
- Neuroimaging
- Neurology
- Alzheimer's Disease Research
Background:
- Medial temporal lobe (MTL) subregion atrophy is an early indicator of Alzheimer's disease (AD).
- Understanding the relationship between MTL volumes and cognitive function is crucial for diagnosing and tracking AD progression.
Purpose of the Study:
- To investigate the association between MTL subregion volumes and cognitive performance in individuals across the AD continuum.
- To identify specific MTL subregions that correlate with cognitive deficits at different stages of AD.
Main Methods:
- Analysis of high-resolution T2-weighted MRI data from 276 participants in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort.
- Categorization of participants into cognitively normal (CN), subjective memory complaints (SMC), early mild cognitive impairment (EMCI), late mild cognitive impairment (LMCI), and AD groups.
- Statistical analysis adjusted for age, education, APOE ε4 status, and intracranial volume (ICV) to examine correlations between MTL volumes and cognitive scores (ADAS-13, MMSE, MoCA, Trail Making Test B, memory recall).
Main Results:
- Significant atrophy in MTL subregions (cornu ammonis, dentate gyrus, subiculum, entorhinal cortex, Brodmann area 35) was observed in AD participants compared to other groups.
- Specific MTL regions showed correlations with cognitive deficits: CA, DG, BA35, and PHC with ADAS-13; CA and SUB with MMSE in LMCI; ERC with MoCA in CN and AD; BA36, CS, and PHC with Trail Making Test B in LMCI.
- Poorer memory recall in AD was linked to CA and DG atrophy, while early MCI showed correlations between verbal learning deficits and atrophy in CA, DG, BA35, SUB, and CS.
Conclusions:
- Atrophy in specific MTL subregions is significantly associated with cognitive impairment across the Alzheimer's disease continuum.
- These MTL subregion volume changes can serve as valuable imaging biomarkers for the early detection and monitoring of cognitive decline in AD.
- The findings highlight the potential of neuroimaging to track disease progression and inform therapeutic strategies in AD research.
