Effects of distraction on threat-related changes in balance control


Postural threat elicits changes in standing balance and broad shifts in attention focus, including directing more attention to balance. Distracting attention from balance using cognitive tasks has been shown to promote more automatic balance control in healthy individuals in non-threatening conditions, and to normalize balance in patients with persistent postural-perceptual dizziness. This study investigated whether distracting attention from balance modified threat-induced changes in standing balance control in healthy young adults. Participants (n=21) stood without (No Threat) and with (Threat) the possibility of receiving a temporally unpredictable anterior-posterior (AP) support surface translation. In the Threat condition, a perturbation was delivered after a pseudo-random delay (5-60s) following the start of each trial; only standing data from 60s trials were analyzed. In both threat conditions, participants completed no task (Control), or mentally counted how often a pre-selected letter (LS), or number (NS) occurred in a sequence. Electrodermal responses (arousal), AP centre of pressure (COP) mean position, root mean square (RMS), mean power frequency (MPF), and low (0-0.05 Hz) and high (0.5-5 Hz) frequency COP, were calculated. Participants significantly increased arousal, leaned further forward, and increased MPF when threatened, independent of task. High frequency COP increased when threatened, however, this increase was significantly smaller for the LS task. Threat-independent reductions in RMS and low frequency COP were observed for the LS compared to Control task. Distracting attention with a specific cognitive task modified threat-induced high frequency changes in standing balance. The generalizability of this effect should be explored for different threat and dual-task scenarios.

Acknowledgments: Natural Sciences and Engineering Research Council of Canada (NSERC)