Can A Simple Virtual Reality Test Determine Early Alzheimer's Risk?
Oct 26 2015
The study included two groups of young adults one carrying the Alzheimer's gene variant, one without it neither of which showed symptoms of the disease.
According to the researchers, the group believed to be at increased genetic risk of Alzheimer's disease "showed a different brain signal many decades before the onset of the disease, and they navigated differently in a virtual environment". Taloa Foster, 33, was arrested for child endangerment.
Scientists discovered that if the grid cells in the entorhinal cortex are affected, the brain tries to compensate using adjacent areas, mainly the hippocampus.
In fact, even stronger evidence for such compensation emerged from a seemingly odd finding - despite the reduction in grid-cell-like representations among high-risk subjects, their performance in the object-location memory tests was comparable to the control group. Participants were then asked to navigate a circular virtual arena.
A team headed by Professor Nikolai Axmacher from the Ruhr-Universitat Bochum, Germany, analyzed the grid cell system in the entorhinal cortex of young students with and without Alzheimer's risk genes. "This suggests that you can either use the grid cell system or you can use the hippocampus", he says.
The high-risk group also had reduced the functioning of brain cells in spatial navigation, as per the researchers. The reason you can close your eyes and still eventually find your way around a room is a result of your grid cells mapping your movements.
What's more, he added, the APOE4 carriers tended to show a different strategy during the test: Typically, they navigated from a vantage point along the border of the virtual arena, while non-carriers preferred to operate from the center.
"Our studies may contribute to a better understanding of early changes of Alzheimer's dementia", says Axmacher.
"These findings are interesting and exciting", said Dr. Luco Gilberto, a neurologist with North Shore-LIJ's Cushing Neuroscience Institute, in Manhasset, New York. But if and when such treatments become available, doctors will need reliable ways to pinpoint high-risk individuals who could benefit.
Dean Hartley, director of science initiatives for the Alzheimer's Association, agreed that the study results hint at a possible new biological marker. They also said that the finding could help in determining why it is hard for people with dementia to navigate the world around them.
"The field is trying to figure out, when does this disease process really begin?"
The results suggest that it may take more than knocking out the grid cell network to cause the navigation issues present in Alzheimer's patients.