Cortical thickness in AD phenotypes: Primary progressive aphasia and amnestic MCI
Poster No:
219
Submission Type:
Abstract Submission
Authors:
Katherine Koenig1, Xuemei Huang1, Aaron Bonner-Jackson1, James Leverenz1, Mark Lowe1, Jagan Pillai1
Institutions:
1The Cleveland Clinic, Cleveland, OH
First Author:
Co-Author(s):
Introduction:
Primary Progressive Aphasia (PPA) is characterized by predominant early language-related decline in neurodegenerative conditions including Alzheimer's disease (AD) (Faroqi-Shah et al, 2020). Previous work has shown that, compared to a typical presentation of AD, those with logopenic progressive aphasia show a different pattern of cortical thinning in the temporal lobe, with greater thinning in the left hemisphere (Butts et al, 2022). Here, we compare MRI-based measures of cortical thickness (CT) in brain regions related to language and memory in two groups: PPA related to AD (aPPA) and amnestic MCI from AD (aMCI). An understanding of cortical and subcortical brain changes specific to aPPA will allow better characterization of the neurodegenerative process in this disorder (Rohrer et al, 2009; Ding et al, 2023).
Methods:
Participants included 17 aMCI patients (mean age 67.8 ± 7.7 years; 8 males) and 28 aPPA patients (mean age 67.8 ± 6.6 years; 14 males). Participants were scanned on a Siemens 3T with a standard 32 channel head coil (Siemens Healthineers, Erlangen). A whole brain MPRAGE (1.2 × 1.3 × 1.3 mm, TE = 0.00277 s, TR = 2.3 s, flip angle = 9°) was acquired and segmented using Freesurfer 7.1.4. For each participant, measures included left and right hippocampal volumes (corrected for estimated intracranial volume) and CT measures as detailed in Figure 1. CT measures were also assessed for hemispheric asymmetry using the asymmetry index (AI): (left - right/left + right)*100. Unpaired t-tests were used to calculate group differences in CT, AI, and hippocampal volumes.
Results:
Patient groups did not differ on age (p < 0.990), sex (p < 0.848), disease duration (p < 0.710), or education (p < 0.119). Figure 1 shows all tested regions, with those surviving a false discovery rate correction for multiple comparisons noted in bold. No group differences were seen in AI. Figure 2 shows group differences in CT in all tested regions. The aPPA group had thinner cortex than the aMCI group in all significant regions. Notably, the most significant group differences were seen in the left hemisphere.
Conclusions:
We found significantly thinner cortex in both language and AD-related regions in aPPA compared to aMCI patients, despite similar disease duration. In agreement with Butts et al. (2022), we found that patients with language impairment showed more cortical thinning on the left, particularly in the fusiform and inferior temporal gyri. In contrast, we did not find preferentially smaller volumes of the hippocampus in the aMCI group. Future work will evaluate clinical correlates.
Disorders of the Nervous System:
Neurodegenerative/ Late Life (eg. Parkinson’s, Alzheimer’s) 1
Neuroanatomy, Physiology, Metabolism and Neurotransmission:
Cortical Anatomy and Brain Mapping 2
Keywords:
Aphasia
Cortex
Degenerative Disease
Language
Memory
Segmentation
STRUCTURAL MRI
Other - Alzheimer's disease
1|2Indicates the priority used for review
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Provide references using APA citation style.
Ding, W. et al. Association of cortical and subcortical microstructure with disease severity: impact on cognitive decline and language impairments in frontotemporal lobar degeneration. Alzheimer’s Res. Ther. 2023; 15: 58.
Faroqi-Shah, Y. et al. Using narratives in differential diagnosis of neurodegenerative syndromes. J. Commun. Disord. 2020; 85: 105994.
Rohrer, J.D. et al. Patterns of cortical thinning in the language variants of frontotemporal lobar degeneration. Neurology. 2009;72(18):1562-1569.