Several brain differences observed among young adults may be a sign of an increased genetic risk for Alzheimer's disease, a new study revealed. The study assessed how the brains of 75 young adults, with whom half carried a gene variant of Apolipoprotein E (APOE), handle spatial navigation.

The study estimated that one in six people carry the APOE4 gene variant which increases the risk for Alzheimer's to three times greater than non-carriers.

To fully examine the respondents, researchers used a magnetic resonance imaging (MRI) test on the young adults' entorhinal cortex, the region of the brain which contains grid cells responsible for spatial navigation. Dr. Nikolai Axmacher of the German Center for Neurodegenerative Diseases said that the entorhinal cortex is one of the first to be affected by the onset of Alzheimer's.

In a study published in the journal Science, Axmacher and his colleagues tracked brain activity in the entorhinal cortex while the respondents navigated thru a virtual maze. The respondents had to use their spatial memory to find several objects in the virtual arena, and then put those objects in designated places.

Researchers found that the grid cells of those with the APOE4 gene showed less activity during the task compared to those without the gene variant. With that, authors of the study wondered if those with the APOE4 gene compensated by using other parts of their brain to navigate the maze.

Axmacher said that while the grid cells were less active, the adjacent brain area, which is the hippocampus, was more active. He said that APOE4 gene carriers navigated the virtual maze with a different strategy, navigating from the border of the virtual arena, while non-carriers worked from the center.

Axmacher warned that it's too soon to know how these differences in brain processing are linked to the detection of Alzheimer's, and it was still unclear what these findings meant. "That is still unclear and needs to be investigated in further studies," he added.

However, scientists hope that the findings will improve the understanding regarding the early signs that could lead to Alzheimer's. Currently, there are no known therapies to treat the disease, but researchers say that early detection will help patients and their families plan for an uncertain future.

Photo : Jirka Matousek | Flickr

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