People with increased risk of Alzheimer's have deficits in navigating


Date:
August 31, 2020
Source:
Ruhr-University Bochum
Summary:
Alzheimer's patients develop severe symptoms of spatial
disorientation as the disease progresses and are unable to find
even the simplest ways.



FULL STORY ==========================================================================
An international research team headed by Anne Bierbrauer, Dr. Lukas
Kunz, Dr.

Carlos Gomez and Professor Nikolai Axmacher from Ruhr-Universita"t
Bochum and Universita"tsklinikum Freiburg now reports that problems in
spatial navigation can also be detected in people with a genetic risk
for Alzheimer's. Their article was published in the journal Science
Advances, released online on 28 August 2020. The team from Bochum,
Freiburg, Dortmund, Sevilla, Madrid, Parma and Brussels explored the
ability of path integration.


========================================================================== Finding paths without external cues Animals and humans have the ability
to follow their own position in space through self-motion cues, even in
the absence of any other sensory information.

"If you get up at night and want to find your way to the bathroom in the
dark, you need -- in addition to knowing the arrangement of your own
home -- a mechanism that tracks your own position in the room without
using external cues," illustrates Anne Bierbrauer. This ability is known
as path integration.

Researchers assume that the activity of so-called grid cells in the
entorhinal cortex is responsible for this ability. When navigating a
spatial environment, these cells display a unique, regular activity
pattern. It has long been known that the entorhinal cortex is crucial
for spatial navigation. It is also one of the first regions of the brain affected by Alzheimer's disease.

Previous study showed changes in grid cell activity In a previous study,
the researchers had shown that grid cells exhibit altered functioning
in people at genetic risk for developing Alzheimer's disease.

However, the test persons did not show any obvious navigation
problems. "We assume that they used compensatory mechanisms to find
their way," explains Nikolai Axmacher, "presumably via external cues
in their surroundings. In Bochum, for example, the winding tower of
the Bergbau-Museum can be seen in many places, as it is often visible
over the rooftops of other buildings." Alzheimer's risk and navigation problems go hand in hand


==========================================================================
In the current study, the team therefore used a computerized navigation
task in which the participants couldn't use external landmarks to
find their way. The researchers compared the navigation performance of
202 volunteers without genetic Alzheimer's risk and 65 volunteers with increased genetic risk. The latter had a specific expression of the gene
for apolipoprotein E, the APOE-e4 allele.

Participants with a genetic risk of Alzheimer's disease didn't perform
as well as the control group.

Insights into grid cell activity An additional group of test persons
performed the same task while the researchers recorded their brain
activity with functional magnetic resonance imaging. The objective of
this experiment was to find out which brain processes play a role in path integration. The team found grid cell representations in the entorhinal
cortex to be specifically associated with navigation without external
cues, which highlights the role of this brain region for path integration.

"In this study, we demonstrated a very specific deficit in healthy
people with a genetically increased risk for Alzheimer's," concludes
Lukas Kunz. "In the future, such behavioural changes might perhaps
help diagnose Alzheimer's disease earlier, before any serious symptoms
appear." Researchers believe that drug therapies for Alzheimer's disease
have so far failed, because the diagnosis is made too late.

Funding The study was funded by the Federal Ministry of Education and
Research (funding code 01GQ1705A), the National Institutes of Health
(NIH, grant 563386), the National Science Foundation (grant BCS-1724243),
the NIH in collaboration with the National Institute of Neurological
Disorders and Stroke (grant U01 NS1113198-01), the German Research
Foundation (EXC 1086, SFB 874, SFB 1280), the Emma and Ernesto Rulfo
Foundation for Medical Genetics, the Spanish Ministry of Economy and Competitiveness (funding codes SAF2017-85310-R and PSI2017-85311-P),
the Regional Ministry of Innovation, Science and Enterprise, Junta
de Andalucia (P12-CTS-2327 to JLC), the International Center on Aging (0348_CIE_6_E) and Ciberned.


========================================================================== Story Source: Materials provided by Ruhr-University_Bochum. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anne Bierbrauer, Lukas Kunz, Carlos A. Gomes, Maike Luhmann, Lorena
Deuker, Stephan Getzmann, Edmund Wascher, Patrick D. Gajewski,
Jan G.

Hengstler, Marina Fernandez-Alvarez, Mercedes Atienza, Davide M.

Cammisuli, Francesco Bonatti, Carlo Pruneti, Antonio Percesepe,
Youssef Bellaali, Bernard Hanseeuw, Bryan A. Strange, Jose
L. Cantero, Nikolai Axmacher. Unmasking selective path integration
deficits in Alzheimer's disease risk carriers. Science Advances,
2020; 6 (35): eaba1394 DOI: 10.1126/sciadv.aba1394 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200831094734.htm

--- up 1 week, 6 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1337:3/111)