Abstract
The effects of aging on cognitive performance must be better understood, especially to protect older individuals who are engaged in risky activities (e.g. aviation). Current literature on executive functions suggests that brain compensatory mechanisms may counter cognitive deterioration due to aging, at least up to certain task load levels. The present study assesses this hypothesis in private pilots engaged in two executive tasks from the standardized CANTAB battery, namely Spatial Working Memory (SWM) and One Touch Stockings of Cambridge (OTS). Sixty-one pilots from three age groups (young, middle-aged, older) performed these two tasks from low to very high difficulty levels, beyond those reported in previous aging studies. A fNIRS headband measured changes in oxyhemoglobin (HbO2) in the prefrontal cortex. Results confirmed an overall effect of the difficulty level in the three age groups, with a decline in task performance and an increase in prefrontal HbO2 signal. Performance of older relative to younger pilots was impaired in both tasks, with the greatest impairment observed for the highest-load Spatial Working Memory task. Consistent with this behavioral deficit in older pilots, a plateau of prefrontal activity was observed at this highest-load level, suggesting that a ceiling in neural resources was reached. When behavioral performance was either equivalent between age groups or only slightly impaired in the older group, there were not any age-related differences in prefrontal activity. Finally, older pilots with extensive flying experience tend to show better preserved spatial working memory performance when compared to mildly-experienced of the same age group. The present findings are discussed in the frames of HAROLD and CRUNCH theoretical models of cognitive and neural aging, evoking the possibility that piloting expertise may contribute to preserve executive functions throughout adulthood.
Highlights
In our contemporary society, global population aging results in an increased number of older individuals engaged in complex and risky occupations such as aviation
Increased dorsolateral prefrontal activity with working memory (WM) task load was consistently observed in both age groups
At the highest task load, older adults may reach a “capacity limit” as suggested by a plateau in prefrontal activity and concomitant impaired performance relative to younger adults. This set of data overall indicates that depending on the cognitive load in executive tasks, equivalent performance in old and young adults would be associated with prefrontal over-recruitment in old adults, whereas impaired performance in old adults may be associated with either similar or lower levels of prefrontal activity relative to young adults
Summary
Global population aging results in an increased number of older individuals engaged in complex and risky occupations such as aviation. Differences in lateral prefrontal activity in older versus younger adults has been observed[13,14] and may contribute to age-related changes in performance, caution is needed as causal relationships cannot be inferred from cross-sectional studies[15] To better explore this issue, studies on executive functions that have considered both the effects of age and task load are highly informative. Reasoning/problem solving is predictive of aeronautical decision-making relevance, in particular in novice pilots[30], and spatial cognition is considered at the heart of the building of pilots’ situation awareness[31,32] It remains open whether middle-aged and older pilots exhibit patterns of performance and neural activity similar to those predicted by CRUNCH and HAROLD models, during spatial WM and planning tasks. We investigated whether this capacity limit would be reached from lower difficulty levels in older vs. younger pilots, and whether flight expertise of older pilots could influence this capacity limit
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