APOE4 is associated with greater atrophy of the hippocampal formation in Alzheimer's disease.
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Date
2011-03-07
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Abstract
Prior studies reported that the hippocampal volume is smaller in Alzheimer s disease patients carrying the Apolipoprotein E 4 allele APOE4 versus patients who are non carriers of this allele This effect however has not been detected consistently possibly because of the regionally specific involvement of the hippocampal formation in Alzheimer s disease The aim of this study was to analyze the local effect of APOE4 on hippocampal atrophy in Alzheimer s disease patients Using high resolution T1 weighted images we investigated 14 patients heterozygous for the 4 allele age 72 8 SD years MMSE 20 4 SD and 14 patients not carrying the 4 allele age 71 10 MMSE 20 5 SD and 28 age sex and education matched controls age 71 8 MMSE 29 1 SD The hippocampal formation was outlined with manual tracing and 3D parametric surface models were created for each subject Radial atrophy was assessed on the whole hippocampal surface using the UCLA mapping technique E4 carriers and non carriers did not differ in their level of impairment in global cognition p 0 91 Mann Whitney test or memory p 0 29 Hippocampal surface analysis showed the typical pattern of CA1 and subicular tissue atrophy in both 4 carriers and non carriers compared with controls e4 carriers pUnder0 0002 4 non carriers pUnder0 01 permutation test The left hippocampal volume was significantly smaller in 4 carriers than non carriers p 0 044 Mann Whitney test the effect of APOE4 mapping to the subicular CA1 region p 0 041 permutation test Differences were not statistically significant in the right hippocampus p 0 20 permutation test These findings show that hippocampal atrophy is greater in APOE4 carriers in regions typically affected by pathology APOE4 may affect the structural expression of Alzheimer s disease