The death of cells in the brain's spatial system could be the reason why elderly people are prone to getting lost,
according to researchers.
A new study compared brain activity patterns in a group of young and older adults as they completed a series of navigational tasks to shed light on why sense of direction tends to fade with age.
They found that an area of the brain that's central to spatial functioning becomes increasingly unstable with age in healthy adults and similarly in people with degenerative diseases such as Alzheimer's.
The findings could ultimately be used to not only slow the deterioration of navigation ability but also to diagnose and treat diseases that cause cognitive decline and give elderly people more independence.
Researchers have found a possible explanation for why elderly people are prone to losing their sense of direction by locating instability in the brain's navigation system, shown in red above
The study by researchers at the German Center for Neurodegenerative Disease was published Thursday in the journal Current Biology.
Spatial orientation and navigation are considered to be some of the most complex abilities of the human mind because they require processing a flood of information including sensory stimuli and balance cues from the muscles.
These skills have been found to deteriorate with age, which can compromise a person's independence later in life.
'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,' lead author Matthias Stangl said.
The study was designed around a hypothesis that the deterioration was related to grid cells, which are important to navigational processing.
The researchers performed a series of experiments using virtual reality and mapping brain activity through functional brain imaging (fMRI).
They split 41 healthy adults into two groups: a 'young' group with 20 participants between ages 19 and 30, and an 'old' group with participants between ages 63 and 81.
For the first experiment participants had to navigate through a virtual reality computer-generated environment while their brain activity were monitored.
In the second experiment participants moved along predefined paths in a real space and virtual reality environment with occasional stops where they had to estimate their distance and orientation relative to the starting point without being able to see or pinpoint its location.
'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,' Thomas Wolbers, the study supervisor and a DZNE senior scientist said.
The results showed that firing patterns in grid cells were less stable in the older group, possibly explaining why older people often struggle with spatial navigation.
Aside from their role in navigation, grid cells are used in other cognitive functions as well.
Wolbers said the findings provide insights into neurophysiological changes in old age that may be used in designing treatments for diseases such as Alzheimer's that cause cognitive decline.
'Assessing navigation performance and grid cell function could possibly facilitate early diagnosis of Alzheimer's and other neurodegenerative disorders,' he said.
While more research is needed in this area, Wolbers said the findings lay the foundation for future studies on age-related decline in health adults and those with brain disorders.
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