Diagnostic value of amygdala volume on structural magnetic resonance imaging in Alzheimer’s disease

Abstract

BACKGROUND The main clinical manifestation of Alzheimer’s disease (AD) is memory loss, which can be accompanied by neuropsychiatric symptoms at different stages of the disease. Amygdala is closely related to emotion and memory. AIM To evaluate the diagnostic value of amygdala on structural magnetic resonance imaging (sMRI) for AD. METHODS In this study, 22 patients with AD and 26 controls were enrolled. Their amygdala volumes were measured by sMRI and analyzed using an automatic analysis software. RESULTS The bilateral amygdala volumes of AD patients were significantly lower than those of the controls and were positively correlated with the hippocampal volumes. Receiver operating characteristic curve analyses showed that the sensitivity of the left and right amygdala volumes in diagnosing AD was 80.8% and 88.5%, respectively. Subgroup analyses showed that amygdala atrophy was more serious in AD patients with neuropsychiatric symptoms, which mainly included irritability (22.73%), sleep difficulties (22.73%), apathy (18.18%), and hallucination (13.64%). CONCLUSION Amygdala volumes measured by sMRI can be used to diagnose AD, and amygdala atrophy is more serious in patients with neuropsychiatric symptoms.

Amygdalar and ERC Rostral Atrophy and Tau Pathology Reconstruction in Preclinical Alzheimer’s Disease

“…The emergent role of the amygdala, here, is supported by our own work in shape diffeomorphometry [18, 19] as well as recent studies in MRI [14], tau PET [21], and tau pathology [58] that have seen similarly high levels of atrophy or tau pathology in the amygdala, particularly in early AD. Further work is needed to sufficiently delineate which areas of the amygdala might be more involved in early AD, but in both brain samples analyzed here, basolateral and basomedial regions of the amygdala, often classified together with the lateral nucleus as “core” amygdala [59], demonstrated higher tau densities as those adjacent to the ERC (Figure 7).…”

“…These shape differences complement recent findings in tau PET illustrating cross-sectional differences in tau load in areas of the rostral MTL including ERC, TEC, and amygdala, in early stages of AD [21]. Two studies have also shown correlation between neuropsychiatric symptom severity and amygdalar atrophy in AD [22,14]. These findings, together with emerging evidence of the neuropsychiatric syndromic complex known as Mild Behavioral Impairment (MBI) amongst individuals prior to the onset of dementia [23,24] suggest amygalar changes early in the disease course may be related to the emotional and behavioral syndrome of MBI.…”

“…Having developed the technology and mathematical infrastructure to integrate these two data types, we are poised to analyze other cohorts to corroborate the putative link between amygdala and ERC atrophy observed in MR imaging to underlying NFT pathology. Second, many previous clinical imaging studies from our own group as well as others [18, 19, 14, 21] have compared control and disease groups only cross-sectionally at a single time point. The longitudinal analysis here tracks subject specific measures over time.…”

“…The amygdala is one region that has undergone relatively limited study in AD [14] compared to its adjoining regions of the ERC and hippocampus in the medial temporal lobe (MTL) highlighted by Braak [5]. Neuropathological and connectivity-based studies suggest a role for the amygdala in neurode-generative diseases such as Agrophylic Grain Disease (AGD) [15], Lewy Body dementia [16], and AD [17] with the inclusion of misfolded proteins and the amygdala’s strong connectivity patterns to areas of the hippocampus, basal ganglia, and basal forebrain [17].…”

Early amygdala and ERC atrophy linked to 3D reconstruction of rostral neurofibrillary tau tangle pathology in Alzheimer’s disease

“…The amygdala is one region that has undergone relatively limited study in AD ( Wang et al, 2021 ) compared to its adjoining regions of the ERC and hippocampus in the medial temporal lobe (MTL) highlighted by Braak and Braak (1991) . Neuropathological and connectivity-based studies suggest a role for the amygdala in neurodegenerative diseases such as Argyrophilic Grain Disease (AGD) ( Ferrer et al, 2008 ), Lewy Body dementia ( Popescu et al, 2004 ), and AD ( Nelson et al, 2018 , Arnold et al, 1991 ) with the observed inclusion of misfolded proteins in the amygdala and the its strong connectivity patterns to areas of the hippocampus, basal ganglia, and basal forebrain ( Nelson et al, 2018 ).…”