Abstract Details

Title Medial temporal lobe subfield volumes are spared in non-amnestic Alzheimer's disease

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P5 - Poster Session 5 (5:30 PM-6:30 PM)

Poster/Presentation
Number 1-001

Objective To precisely localize hippocampal volume differences between amnestic and non-amnestic Alzheimer’s disease (AD) patients using T2-weighted imaging and subfield segmentation.

Background Non-amnestic AD is characterized by relative sparing of the hippocampus; however, the magnitude and spatial distribution of hippocampal atrophy in non-amnestic AD remain uncertain.

Design/Methods The sample comprised 49 patients with autopsy or cerebrospinal fluid evidence for underlying AD pathology: 20 patients with typical, amnestic AD and 29 patients with non-amnestic syndromes including primary progressive aphasia (n=10), corticobasal syndrome (n=7), posterior cortical atrophy (n=4), and behavioral/dysexecutive syndromes (n=8). Patients were compared to 13 matched controls. Participants were scanned with a T2-weighted turbo spin echo sequence with 0.4 mm in-plane resolution and 2 mm slices oriented perpendicular to the longitudinal axis of the hippocampus. Subiculum, CA1, and dentate gyrus/CA4 (DG) were segmented using the Automated Segmentation of Hippocampal Subfields algorithm and checked by expert raters. Perirhinal (BA 35/36) and entorhinal cortex volumes were normalized by number of slices. Volume differences were analyzed using a linear mixed effects model with fixed factors of subfield, group (non-amnestic, amnestic, or control), the subfield x group interaction, intracranial volume, and age. A random intercept for hemisphere nested within participant accounted for phenotypic variability in the lateralization of disease.

Results Volumes did not differ in perirhinal or entorhinal cortex. In subiculum, amnestic patients had significantly lower volumes than controls (p<0.001, corrected), and non-amnestic patients had marginally higher volumes than amnestic patients (p<0.07, corrected). In CA1 and DG, both patient groups had significantly lower volumes than controls (all p<0.001, corrected), and amnestic patients had lower volumes than non-amnestic patients (both p<0.001, corrected).

Conclusions Non-amnestic patients had relatively spared grey matter volume across subfields of the hippocampus relative to amnestic AD patients, consistent with findings of lower hippocampal pathology and atrophy in this group.

Authors/Disclosures
Jeffrey S. Phillips, PhD (Penn FTD Center, Department of Neurology) PRESENTER	No disclosure on file
	No disclosure on file
	No disclosure on file
James M. Gee (University of Utah)	No disclosure on file
Murray Grossman, MD, FAAN (University of Pennsylvania)	Dr. Grossman has received personal compensation in the range of $5,000-$9,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Neurology. The institution of Dr. Grossman has received research support from NIH.
David Irwin, MD (University of Pennsylvania)	The institution of Dr. Irwin has received research support from NIH. The institution of Dr. Irwin has received research support from Prevail. The institution of Dr. Irwin has received research support from Passage Bio. The institution of Dr. Irwin has received research support from Alector. The institution of Dr. Irwin has received research support from Transposon. The institution of Dr. Irwin has received research support from Denali. The institution of Dr. Irwin has received research support from Cervo Med.

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