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Abstract:
The epsilon 4 (E4) allele of the apolipoprotein E gene (ApoE)
confers an increased risk for the development of Alzheimer's
Disease and may be associated with reductions in hippocampal
volume. The present study examined longitudinal change in
hippocampal volume as a function of ApoE genotype in non-demented
elderly individuals (mean age=69.2 years). Twelve subjects positive
for the E4 allele (E4+) were matched on sex, race, age and years of
education to 12 subjects negative for the E4 allele (E4-). Each
subject underwent 2 MRI scans, separated by a mean interval of 2.83
years. Hippocampal volumes were parcellated using a standardized
protocol by two operators, blinded to genotype and scan order
(reliabilities>.91). Across both groups, there was a main effect
of time during which hippocampal volume decreased at a rate of
34.26 mm3/year (p<.01). In addition, there was a trend for E4+
to have greater longitudinal decline in hippocampal volume than E4-
(p<.08); rates of decline in E4+ and E4- were 54.90 mm3/year and
13.63 mm3/year, respectively. Adjusting for brain volume did not
affect the findings. These results demonstrate significant
longitudinal decline in hippocampal volume and raise the
possibility that individuals positive for the E4 allele may show a
steeper rate of decline than their E4- counterparts.
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