Tuesday, April 6, 2021

Some navigation abilities decline in midlife and differ by sex, but others (path integration) do not decline

Age-Related Changes in Spatial Navigation Are Evident by Midlife and Differ by Sex. Shuying Yu et al. Psychological Science, April 5, 2021. https://doi.org/10.1177/0956797620979185

Abstract: Accumulating evidence suggests that distinct aspects of successful navigation—path integration, spatial-knowledge acquisition, and navigation strategies—change with advanced age. Yet few studies have established whether navigation deficits emerge early in the aging process (prior to age 65) or whether early age-related deficits vary by sex. Here, we probed healthy young adults (ages 18–28) and midlife adults (ages 43–61) on three essential aspects of navigation. We found, first, that path-integration ability shows negligible effects of sex or age. Second, robust sex differences in spatial-knowledge acquisition are observed not only in young adulthood but also, although with diminished effect, at midlife. Third, by midlife, men and women show decreased ability to acquire spatial knowledge and increased reliance on taking habitual paths. Together, our findings indicate that age-related changes in navigation ability and strategy are evident as early as midlife and that path-integration ability is spared, to some extent, in the transition from youth to middle age.

Keywords: cognitive aging, virtual reality, path integration, wayfinding

Check also Gender differences in spatial navigation: Characterizing wayfinding behaviors. Ascher K. Munion et al. Psychonomic Bulletin & Review, August 20 2019. https://www.bipartisanalliance.com/2019/08/gender-differences-in-spatial.html

And: A meta-analysis of sex differences in human navigation skills. Alina Nazareth et al. Psychonomic Bulletin & Review, July 3 2019. https://www.bipartisanalliance.com/2019/07/a-meta-analysis-of-sex-differences-in.html

The present study tested the effects of age and sex on three core aspects of spatial navigation in young and midlife adults: path integration, spatial-knowledge acquisition, and navigational strategy. Building on previous chronological-aging studies (Driscoll et al., 2005Zhong & Moffat, 2016), we found that some age-related differences in spatial navigation are evident by midlife. Although path-integration ability was largely preserved with age in the loop-closure task, pronounced age-related differences were observed in the ability to acquire spatial knowledge in the maze-learning task and in the selection of a navigational strategy in the dual-solution paradigm. No major sex difference was observed for path integration, but sex differences were found for acquiring spatial knowledge and navigation strategy. Overall, sex differences present in young adults tended to be reduced with age.

Previous findings indicate poor path integration in adults 65 years or older (Adamo et al., 2012Coughlan, Coutrot, et al., 2018Harris & Wolbers, 2012), but we saw no such change in midlife adults, suggesting that age-related changes arise later in the aging process. In previous studies, older adults had access to a single cue (vision or proprioception), whereas our task provided participants with multiple cues. Future studies should examine whether reduced performance is evident in midlife when performance is constrained to a single cue. Although there was a sex difference in degrees traveled, with women tending to overshoot and men tending to undershoot, this difference did not affect the overall position error. The tendency to overshoot could be a cautionary measure by women to ensure they reach the start (e.g., Gagnon et al., 2016). In sum, we found little evidence for sex or aging effects in path integration.

Sex differences were evident in measures of spatial-knowledge acquisition from both unrestricted free exploration (maze-learning task) and route-based learning (dual-solution paradigm). In the maze-learning task, midlife adults did not explore as much as younger adults. After accounting for differing numbers of exploration moves, we found that sex differences remained robust in young adults and diminished in midlife adults. Floor effects were present in the maze-learning task for midlife adults, making sex differences less detectible. It is possible that age-related changes in the brain hinder the ability for midlife adults to create a comprehensive cognitive map, which in turn makes sex differences in performance harder to detect. In the dual-solution paradigm, wayfinding success indicates how well participants learned the environment from a route. Despite equal exposure to the route, midlife adults were less successful than younger adults, consistent with previous studies on learning from routes (Harris & Wolbers, 2014Wiener et al., 2013Zhong & Moffat, 2016). Together, these findings suggest that spatial learning is impaired as early as midlife. These data are consistent with findings from an earlier study demonstrating age-related performance decrements in a virtual Morris water-maze task by midlife (Driscoll et al., 2005).

Navigation strategies in the dual-solution paradigm indicated that young men took more shortcuts than young women, a finding that echoes previous results by Boone et al. (20182019). Our study provides the first evidence that age-related differences in navigation strategies are evident by midlife, with midlife adults using fewer shortcuts than younger adults. This result is consistent with reports that older adults use more habitual routes when navigating (Harris et al., 2012Lester et al., 2017Wiener et al., 2013) and suggests that strategies have already shifted by midlife. In addition, we found that the sex difference observed in young adults did not persist in midlife adults. Further, the heat maps indicated that although young men were more likely to take shortcuts through the middle of the maze, all other groups relied on the learned route to navigate within the maze. Thus, the major change with age was a reduction of place-based strategies in men.

Several limitations should be considered when interpreting these findings. First, it is possible that older adults have less experience with using computer gaming controls (such as those used in the dual-solution paradigm) compared with younger adults, and this could contribute to navigation inefficiency in the desktop virtual environments. However, age-related differences also existed for the maze-learning task, which requires the use of only a single button press at each intersection. This indicates that poorer performance for midlife adults is unlikely to be due to computer experience alone and is likely to be related to age-related changes in participants’ brains that deterred successful acquisition of spatial information from the environment. A direct assessment of participants’ gaming experience and experience in virtual environments was not acquired, so this issue cannot be fully resolved.

Second, the midlife period is characterized by significant neuroendocrine changes in women. Our sample included midlife women, spanning the spectrum from late premenopausal to early postmenopausal. Although the study was not powered to assess performance by reproductive stage or endocrine status in the current sample, this will be a major focus of our future research. Further, young adult women were tested independently of menstrual-cycle stage. Given accumulating evidence that menstrual-cycle stage and sex-hormone concentrations impact spatial cognition (Courvoisier et al., 2013Hussain et al., 2016) and aspects of navigation (Korol et al., 2004), future studies should clarify the extent to which these relationships hold across measures of path integration, wayfinding, and navigation strategy.

Finally, the largest age effects were observed in men, with a steep decline in wayfinding success (maze-learning task) and a shift toward taking habitual routes (dual-solution paradigm). It is possible that these unexpected effects have a neuroendocrine basis. Testosterone production in men begins to diminish when they are in their early 30s and gradually declines throughout the adult life span (Feldman et al., 2002). Testosterone loss influences cognitive and brain function in aging men, including visual and verbal memory and spatial cognition (Moffat, 2005). Driscoll and colleagues (2005) found that the male spatial advantage in a virtual Morris water-maze task is related to circulating testosterone. Thus, the role of testosterone should be considered as a factor in future studies of navigation and aging.

In sum, we examined signatures of early aging in three navigational tasks, opening up new avenues for understanding healthy aging. The differing patterns of age and sex across our three navigational tasks suggest that different aspects of navigation could tap into separate brain systems. Although path integration has typically been used as an early marker for dementia (Coughlan, Laczó, et al., 2018Kunz et al., 2015), our findings suggest that spatial-knowledge acquisition and strategy use are more sensitive to the earliest stages of the aging process. Understanding the trajectories of healthy aging—and how they differ for men and women—will help pave the way for developing behavioral and neural markers for dementia.

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