Experts at the German Center for Neurodegenerative Disease (DZNE) have found a possible reason why older people often become disoriented and tend to get lost easily. In elderly adults, the team discovered unstable activity in the region of the brain that is primarily responsible for spatial navigation.
Spatial orientation and navigation are two of the most complex tasks performed by the human brain. The mind’s ability to perform these activities is negatively influenced by age, which threatens the independence of older adults as well as their quality of life.
“When you move around an unfamiliar environment, it is perfectly normal to get lost,” explained first author Matthias Stangl. “Yet, this tends to happen more often to older people. So far, we know very little about the underlying neuronal mechanisms of these navigation problems.”
“We had the hypothesis that so-called grid cells might be implicated. A major part of the navigational processing is done by these cells. They are specialized neurons located in the brain’s entorhinal cortex. Therefore, we guessed that deficits in grid cell function might be a cause for problems in navigation.”
To test this theory, the team conducted trials with 41 healthy younger and older adults. The study participants were divided in two groups: young adults between the ages of 19 and 30, and older adults between the ages of 63 and 81.
The experiments were designed to test the navigational and path integration abilities of the individuals.
“All things considered, young participants did better in navigation, which is in line with previous studies,” said study supervisor Thomas Wolbers. “However, we found an association between decreased navigational performance and deficits in grid cell activity.”
“Grid cells fired differently when comparing young and old adults. Specifically, firing patterns were less stable over time in older individuals, which indicates that these brain circuits are compromised in old age. This might be a cause of why many senior people tend to have troubles with spatial navigation.”
Professor Wolbers explained that grid cells not only play a central role in navigation, but also in other cognitive functions.
“Therefore, our findings might indicate a key mechanism underlying cognitive deficits in old age. Not only does this provide insights into neurophysiological changes due to aging. It may also help in designing therapies against age-related cognitive decline,” said Professor Wolbers.
The study is published in the journal Current Biology.
By Chrissy Sexton, Earth.com Staff Writer