FRIDAY, Jan. 13 (HealthDay News) -- Healthy individuals with a family history of Alzheimer disease who carry the apolipoprotein E (APOE) e4 allele show reduced activity in memory-related brain regions, including the hippocampus, compared with their peers with the e3 allele, researchers report in the Jan. 13 issue of BMC Medicine.
Sterling C. Johnson, Ph.D., and colleagues from the University of Wisconsin Medical School in Madison, studied 40 healthy individuals with a mean age of 54 who had at least one parent with Alzheimer disease. Of these, 23 carried one copy of the APOE e3 allele and one copy of the APOE e4 (e3/4), while the remaining 17 carried two copies of the APOE e3 (e3/3). Participants were asked to perform a task to distinguish between novel and previously learned items, during which their brain activity was examined by functional magnetic resonance imaging.
APOE e3/4 individuals showed reduced activation in the hippocampus and medial temporal lobe during the task compared with e3/3 individuals. The association did not appear to be related to defects in cognitive function, since the two groups were similar in terms of age, education, and memory and neurophysiological functions.
"Together with previous studies reporting reduced glucose metabolism and Alzheimer disease-related neuropathology, this study provides convergent validity for the idea that the medial temporal lobe exhibits functional decline associated with the APOE e4 allele," Johnson and colleagues conclude. This group of patients "may represent a good study population for novel treatments designed to delay the onset of or to prevent Alzheimer disease."
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