MRI measures of entorhinal cortex vs hippocampus in preclinical AD

TLDR

MRI measures of the entorhinal cortex and hippocampus are used to predict progression to AD in nondemented individuals with memory problems, but their relative accuracy is controversial. This study compares entorhinal cortex and hippocampal MRI measures to predict who will develop AD. MRI volumes of the entorhinal cortex and hippocampus were obtained from 137 participants across four groups: normal cognition, memory difficulty without dementia, memory difficulty progressing to probable AD, and mild AD. The entorhinal cortex volume distinguished future AD cases with 84% accuracy, whereas hippocampal volume did not, and both regions differed across groups and correlated with memory performance, supporting early entorhinal involvement in preclinical AD.

Abstract

<b><i><i>Background:</i></i></b> MRI measures of the entorhinal cortex and the hippocampus have been used to predict which nondemented individuals with memory problems will progress to meet criteria for AD on follow-up, but their relative accuracy remains controversial. <b><i><i>Objectives:</i></i></b> To compare MRI measures of the entorhinal cortex and the hippocampus for predicting who will develop AD. <b><i><i>Methods:</i></i></b> MRI volumes of the entorhinal cortex and the hippocampus were obtained in 137 individuals comprising four groups: 1) individuals with normal cognition both at baseline and after 3 years of follow-up (n = 28), 2) subjects with memory difficulty but not dementia both at baseline and after 3 years of follow-up (n = 73), 3) subjects with memory difficulty at baseline who were diagnosed with probable AD within 3 years of follow-up (n = 21), and 4) patients with mild AD at baseline (n = 16). <b><i><i>Results:</i></i></b> Measures of both the entorhinal cortex and the hippocampus were different for each of the pairwise comparisons between the groups (<i>p</i> &lt; 0.001) and were correlated with tests of memory (<i>p</i> &lt; 0.01). However, the volume of the entorhinal cortex differentiated the subjects from those destined to develop dementia with considerable accuracy (84%), whereas the measure of the hippocampus did not. <b><i><i>Conclusion:</i></i></b> These findings are consistent with neuropathologic data showing substantial involvement of the entorhinal cortex in the preclinical phase of AD and suggest that, as the disease spreads, atrophic change develops within the hippocampus, which is measurable on MRI.