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Young Adults With Alzheimer's Risk and Spatial Navigation • Mirror Daily

(Mirror Daily, United States) – A small study has published some worrying results for young adults with Alzheimer’s risk in their genetic heritage: they might already present some symptoms in the way their brains deal with spatial navigation.

Researchers are however still cautious in saying for sure that these brain differences are a precursor of Alzheimer’s; leading author Dr. Nikolai Axmacher, a researcher at the German Center for Neurodegenerative Diseases, Bonn, said further investigations are required in order to establish a certain connection.

Dr. Axmacher hopes the results of this study will provide some insight for researchers who try to understand the processes that might lead to an early onset of Alzheimer’s – the most common form of dementia. Axmacher added that if these brain differences prove to be the first changes that predict the disease, they could be used as an identifier for high-risk people.

Published in the journal Science, the study analyzed 35 young adults – and 35 others used as control group – who were carriers of a variant of the APOE gene, the one researchers believe it can increase the risk of Alzheimer’s. One in 6 people carry this APOE4 variant, which comes with a threefold greater risk of developing Alzheimer’s than non-carriers.

Using an advanced form of MRI to monitor the participants’ brain, researchers were most interested in the entorhinal cortex, where “grid cells” are located. These cells are the one managing spatial navigation – which goes south really fast when Alzheimer’s onset begins.

Participants were asked to navigate in a virtual arena, a task that engaged their spatial memory: all they had to do was to remember the location of objects and then make sure they placed the objects in their initial place. Results showed the brains of APOE4 carriers had less activity in their grid cells during the task than the adults in the control group.

However, it was surprising to see that performances of both groups were almost similar, which made researchers wonder if APOE4 carriers were more likely to use other brain regions for navigation in order to compensate what they lacked in grid cells functionality.

When they knew what to look for, researchers soon discovered that less activity in the grid cell system meant a more active hippocampus, which is located in an adjacent brain area. Even though they are still unsure of what this means, previous studies hinted that excess activity in the hippocampus could also lead to Alzheimer’s.
Image Source: Flickr

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