Multi-modal imaging predicts memory performance in normal aging and cognitive decline

Abstract

This study (n=161) related morphometric MR imaging, FDG-PET and APOE genotype to memory scores in normal controls (NC), mild cognitive impairment (MCI) and Alzheimer's disease (AD). Stepwise regression analyses focused on morphometric and metabolic characteristics of the episodic memory network: hippocampus, entorhinal, parahippocampal, retrosplenial, posterior cingulate, precuneus, inferior parietal, and lateral orbitofrontal cortices. In NC, hippocampal metabolism predicted learning; entorhinal metabolism predicted recognition; and hippocampal metabolism predicted recall. In MCI, thickness of the entorhinal and precuneus cortices predicted learning, while parahippocampal metabolism predicted recognition. In AD, posterior cingulate cortical thickness predicted learning, while APOE genotype predicted recognition. In the total sample, hippocampal volume and metabolism, cortical thickness of the precuneus, and inferior parietal metabolism predicted learning; hippocampal volume and metabolism, parahippocampal thickness and APOE genotype predicted recognition. Imaging methods appear complementary and differentially sensitive to memory in health and disease. Medial temporal and parietal metabolism and morphometry best explained memory variance. Medial temporal characteristics were related to learning, recall and recognition, while parietal structures only predicted learning.

Figure 1

A) The hippocampus segmentation shown in gold on a coronal slice (top part) and as 3D renderings (top: head, bottom: tail). B) Along with the hippocampal formation, the cortical areas shown here are part of the episodic memory network. Shown here are pial cortical representations of selected parcellations in the left hemisphere. From left to right: medial, ventral and lateral views

Figure 1

A) The hippocampus segmentation shown in gold on a coronal slice (top part) and as 3D renderings (top: head, bottom: tail). B) Along with the hippocampal formation, the cortical areas shown here are part of the episodic memory network. Shown here are pial cortical representations of selected parcellations in the left hemisphere. From left to right: medial, ventral and lateral views

Figure 2

The distribution of allelic combinations of APOE in the three groups. The proportionalized allele frequency within each group was as follows: NC: 2.1% 4/4, 17.0% 3/4, 59.6% 3/3, 21.3% 2/2-3, MCI: 14.1% 4/4, 38.5% 3/4, 41.0% 3/3, 6.4% 2/2-3, AD: 30.6% 4/4, 47.2% 3/4, 22.2 % 3/3, 0% 2/2-3.

Figure 3

Bar chart showing MR values for hippocampal volume and thickness of each cortical ROI for the different groups. All values are standardized residuals after the effects of age and gender have been regressed out. A one-way ANOVA showed significant main effects of group for morphometry in all ROIs, as indicated by an asterisk ( _* ). Hippo: Hippocampus, Entorh: Entorhinal cortex; Parahi: Parahippocampal gyrus; Retrospl: Retrosplenial cortex; PC: Posterior cingulate; Precun: Precuneus; Inf. P: Inferior parietal gyrus; L. Orbf: Lateral Orbitofrontal gyrus;.

Figure 4

Bar chart showing FDG_PET values for hippocampal volume and thickness of each cortical ROI for the different groups. All values are standardized residuals after the effects of age, gender, and volume (for hippocampus) or thickness (for cortical ROIs) have been regressed out.. As indicated by asterisks ( _* ), a one-way ANOVA showed significant main effects of group for all ROIs. Hippo: Hippocampus, Entorh: Entorhinal cortex; Parahi: Parahippocampal gyrus; Retrospl: Retrosplenial cortex; PC: Posterior cingulate; Precun: Precuneus; Inf. P: Inferior parietal gyrus; L. Orbf: Lateral Orbitofrontal gyrus;.

Figure 5

Scatterplots showing the linear relationships of the metabolic and morphometric ROIs uniquely predicting learning and recognition in each group.

Figure 6

Scatter plots showing the linear relationships of the metabolic and morphometric ROIs uniquely predicting learning and recognition and in the total sample.