Age-related effects on dynamic postural stability and prefrontal cortex activation during precision fitting tasks.

Abstract

Background: Dynamic postural control is impaired in older adults, as evidenced from worse dynamic postural stability compared to young adults during upright stance while concurrent goal-directed tasks. Prefrontal cortex (PFC) is considered to play an important role in goal-directed tasks. This study aimed to investigate the age effects on dynamic postural stability and PFC activation during precision fitting tasks.

Methods: Participant performed precision fitting tasks under four different conditions: large opening size with their arm's length (close-large), small opening size with their arm's length (close-small), large opening size with 1.3 times arm's length (far-large), and small opening size with 1.3 times arm's length (far-small). We analyzed the center of pressure-related outcomes representing dynamic postural stability and PFC activation at the six different subregions from healthy older adults (n = 15, 68.0 ± 3.5 years), and gender-matched middle-aged (n = 15, 48.73 ± 3.06 years) and young (n = 15, 19.47 ± 0.64 years) adults.

Results: The dynamic postural stability presented the young > middle-aged > older groups across the conditions. Specifically, the young group presented better dynamic postural stability than the older group in the close-large, far-large, and far-small conditions (p < .05), while showed better dynamic postural stability than the middle-aged group in the close-large condition (p < .05). Additionally, the older group had greater PFC activation at all PFC subregions than the young group (p < .05), while had greater activation at left dorsolateral and ventrolateral PFC than the middle-aged group (p < .05). The middle-aged group presented greater activation at left dorsomedial PFC than the young group (p < .05).

Conclusion: Heightened dorsomedial PFC activation in middle-aged adults compared to young adults may reflect a deficit in processing the visuomotor information during the precision fitting tasks. Degeneration of the ability in automatic coordination of dynamic postural control may begin to occur at midlife.