Young adults who carry a gene linked to Alzheimer’s disease navigate virtual environments differently from those without the genetic risk factor, according to new research that could open a fresh route to early detection of the condition.
The study, led by scientists at the German Center for Neurodegenerative Diseases and published in the journal Science, found that people aged between 18 and 30 who carry the APOE e4 gene variant — which is associated with increased Alzheimer’s risk — showed measurable differences in both brain activity and movement behaviour during a virtual maze test, even though their overall performance scores were similar to those without the gene.
Participants were asked to navigate a computer-generated environment, collect virtual objects, and return them to their original locations after a period of time. Brain activity was monitored throughout using functional MRI scanning.
Those without the genetic risk factor moved freely across the full virtual space, while the at-risk group showed a distinct tendency to stay close to the edges of the environment. Researchers also found that the at-risk participants were relying on a different part of the brain to complete the tasks — drawing on the hippocampus rather than the grid-cell network in the entorhinal cortex.
Grid cells are a group of specialised brain cells used for spatial memory and navigation. Alzheimer’s patients are known to develop abnormalities in the entorhinal cortex, the region where these cells are located, which has led researchers to investigate whether reduced grid-cell activity in younger people could serve as an early warning sign.
Study co-author Nikolai Axmacher noted increased hippocampal activity specifically among the at-risk participants, suggesting the brain may be compensating for reduced reliance on the grid-cell system at this stage. Whether that compensation holds as people age remains a key question for future research.
Joshua Jacobs, a neuroscientist at Columbia University who was not involved in the study, said the findings highlight a meaningful connection between grid-cell function and real navigational behaviour in humans.
The research team said their results could form a new framework for preclinical Alzheimer’s investigation, though they emphasised that carrying the APOE e4 variant does not mean a person will develop the disease.
Dr Laura Phipps of Alzheimer’s Research UK said identifying early brain changes associated with genetic risk remains an important step toward understanding why some individuals are more susceptible later in life, noting that age, genetics and lifestyle all contribute to overall risk.
Further work is needed before virtual navigation testing could be considered for clinical use, but scientists say the approach represents a promising and non-invasive direction for early-stage research.
