Researchers Identify Precursor to Alzheimer's

Healthy individuals who are at risk of Alzheimer's disease show reduced activity in the hippocampal region of the brain when performing tasks related to forming new memories, according to US researchers.

The scientists observed that individuals carrying the apolipoprotein E (APOE) epsilon4 gene formation, which has previously been associated with high risk of developing Alzheimer's disease (AD), showed altered brain activity compared to APOE epsilon3 homozygotes.

According to the researchers, this supports the idea that certain regions of the brain exhibit functional decline associated with the AOPE epsilon4 gene formation, and this decline begins before the onset of AD symptoms.

In the study the participants were asked to distinguish between images that they were being shown for the first time and images that they had already memorized previously in a pre-scan training session.

During the task, the epsilon3/4 heterozygotes showed reduced activation in the medial temporal lobe of the brain (MTL), including the right hippocampus, compared to the epsilon3/3 homozygotes.

There were no differences between the two groups in age, education, performance during the task or neuropsychological assessment of memory; therefore the altered brain activation seen could not have been caused by impaired cognitive function.

According to the authors, "if compromised MTL function continues to be observed in healthy epsilon4 carriers, this group of subjects may represent a good study population for novel treatments designed to delay the onset or to prevent the development of AD".

The research was carried out by a team from the University of Wisconsin Medical School and the William S Middleton Memorial VA Hospital.

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