Abstract
Older age is associated with changes in the brain, including the medial temporal lobe, which may result in mild spatial navigation deficits, especially in allocentric navigation. The aim of the study was to characterize the profile of real-space allocentric (world-centered, hippocampus-dependent) and egocentric (body-centered, parietal lobe dependent) navigation and learning in young vs. older adults, and to assess a possible influence of gender. We recruited healthy participants without cognitive deficits on standard neuropsychological testing, white matter lesions or pronounced hippocampal atrophy: 24 young participants (18–26 years old) and 44 older participants stratified as participants 60–70 years old (n = 24) and participants 71–84 years old (n = 20). All underwent spatial navigation testing in the real-space human analog of the Morris Water Maze, which has the advantage of assessing separately allocentric and egocentric navigation and learning. Of the eight consecutive trials, trials 2–8 were used to reduce bias by a rebound effect (more dramatic changes in performance between trials 1 and 2 relative to subsequent trials). The participants who were 71–84 years old (p < 0.001), but not those 60–70 years old, showed deficits in allocentric navigation compared to the young participants. There were no differences in egocentric navigation. All three groups showed spatial learning effect (p’ s ≤ 0.01). There were no gender differences in spatial navigation and learning. Linear regression limited to older participants showed linear (β = 0.30, p = 0.045) and quadratic (β = 0.30, p = 0.046) effect of age on allocentric navigation. There was no effect of age on egocentric navigation. These results demonstrate that navigation deficits in older age may be limited to allocentric navigation, whereas egocentric navigation and learning may remain preserved. This specific pattern of spatial navigation impairment may help differentiate normal aging from prodromal Alzheimer’s disease.
Highlights
Aging involves accumulation of adverse biological, psychological, and social changes over time (Bowen and Atwood, 2004) that may or may not signal pathology
We first addressed our first hypothesis that spatial navigation performance would be impaired in older participants
We found a significant main effect for group performance in the allocentric subtask (F[2,64] = 9.40; p < 0.001), where the participants 71–84 years old consistently exhibited poorer overall spatial navigation accuracy than the participants 60–70 years old (p < 0.001; Figure 2)
Summary
Aging involves accumulation of adverse biological, psychological, and social changes over time (Bowen and Atwood, 2004) that may or may not signal pathology. Age-related changes interfere unevenly with cognitive functioning (Gazova et al, 2012). While certain cognitive domains do show a decline, other may remain stable (Burke and Barnes, 2006). Navigation in space is a complex cognitive function that is essential for independence, safety, and quality of life. Differences in spatial navigation between young and older adults were demonstrated by previous research (Barrash, 1994; Wilkniss et al, 1997; Burns, 1999; Newman and Kaszniak, 2000; Moffat and Resnick, 2002; Driscoll et al, 2005; Iaria et al, 2009; Head and Isom, 2010; Jansen et al, 2010). The decline in spatial navigation was shown to be apparent after 60 years of age and further accelerated after
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