NEW YORK (Reuters Health) - On tests of learning and memory, healthy nondemented older adults with the APOE-e4 allele, a risk factor for Alzheimer’s disease, appear to have to work harder to achieve comparable scores than their counterparts with the APOE-e3 allele.
“This study confirms alterations in brain activity during learning in healthy older people at genetic risk for Alzheimer’s disease,” Dr. Mark W. Bondi from the VA San Diego Healthcare System told Reuters Health.
To determine the influence of APOE genotype on brain responses, Dr. Bondi and colleagues had 20 nondemented adults with normal learning and memory capabilities complete a picture-encoding task during functional magnetic resonance imaging studies. The average age was 76 years old.
In multiple brain regions, the 10 subjects with the APOE-e4 allele compared with the 10 subjects with the APOE-e3 allele displayed greater intensity and extent of brain activation, measured as blood oxygen level dependent (BOLD) brain response, while learning new pictures.
The APOE-e4 group also displayed lower brain responses in the left hippocampus during tasks of learning and memory, according to the report in the February 8th issue of Neurology.
These differences appear to be due directly to APOE genotype and support the compensatory hypothesis wherein APOE-e4 carriers “appear to require additional cognitive effort to achieve the same level of performance.”
“The implications of this finding,” Dr. Bondi told Reuters Health, “include the possibility of providing new methods for identifying the earliest stages of Alzheimer’s disease.”
“Such efforts will help us recognize brain changes early so that we can identify the people at highest risk for the disease with the goal of providing them with treatment more quickly and efficiently,” he added.
Source: Neurology 2005;64:501-508. [ Google search on this article ]
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