It has long been noticed that the sense of direction deteriorates as we age, but scientists have not known entirely why. Now, experts believe it could be the result of cells in the spatial system of the brain dying off.
Researchers at the German Center for Neurodegenerative Disease made comparisons in the brain activity patterns between two groups – one consisting of younger adults and another of older people. They both completed various navigational tasks to help offer insight into the problem.
What was discovered was that an area of the brain associated with spatial functioning loses its stability as individuals age. It was seen in both healthy patients and those who have been diagnosed with neurodegenerative diseases, of which Alzheimer’s is the most well-known.
This new information could lead to treatments to help slow down the deterioration of navigational competence. It could also be used in overcoming cognitive problems and therefore enable elderly people to keep their independence for longer.
The ability to orientate spatially and to navigate are thought to be among the most complex functions the brain performs. It requires the mind to process multiple pieces of information, including sensory stimuli and cues from the muscles about balance.
Matthias Stangl, lead author of the study, said: “When you move around an unfamiliar environment, it is perfectly normal to get lost. 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.”
Research into the issue began with the hypothesis that the deterioration had something to do with grid cells, which were already known to be important in processing navigational information. The scientists then used functional brain imaging (fMRI) and virtual reality to ascertain what was happening.
Both groups – the younger and the older adults – were asked to carry out two tasks. The first was to have their brain monitored while they navigated their way through a virtual reality computer-generated environment.
Secondly, the participants made their way along predetermined paths in a real space and virtual reality setting. Along the way, they were asked to make stops to estimate how far they were from the starting point and in which direction it lay.
Thomas Wolbers, a senior scientist at the centre and study supervisor, reflected on the results. He said: “All things considered, young participants did better in navigation, which is in line with previous studies. However, we found an association between decreased navigational performance and deficits in grid cell activity.”
Seeing that the firing patterns in grid cells were less stable in the older participants offered a possible explanation as to why elderly people find spatial navigation more difficult. Since these cells are also used for other cognitive functions, there could be an interesting link.
Mr Wolbers highlighted the potential the findings hold for designing treatments for cognitive conditions like Alzheimer’s. Such insights into neurophysiological changes in old age could also prove invaluable for early diagnosis.
It is likely that this research will be used as a starting point for more studies into age-related decline, an issue that is becoming particularly pressing as the population gets older.