325 DISTINCT INTEGRATION OF RAPIDLY PRESENTED AUDIO-VISUAL EVENTS IN OLDER ADULT RECURRENT FALLERS

Abstract

Abstract Background The ability to precisely integrate sensory information is critical to everyday functions, including balance/postural control and navigation. Older adults typically integrate sensory information over longer time delays than younger adults, which can reduce the precision of their perceptual judgments. This is particularly evident in older adults with a recent history of falls. However, the extent to which longitudinal patterns of falling or fall risk are associated with the precision of multisensory integration in older adults remains uncertain. Methods A sample of 2,321 older adults were grouped into longitudinal trajectories via self-report fall number (decreasing, stable, increasing) and, separately, sensorimotor fall risk via Timed-Up-and-Go (TUG) performance (stable, moderately declining, severely declining). Multisensory integration was measured once with the Sound Induced Flash Illusion, which examines how sound influences vision. A single ‘flash’ and two ‘beeps’ were presented over short (70ms) and longer (150ms and 230ms) temporal delays and older adults were asked to report only the number of ‘flashes’ they perceived. Accuracy on this task was the main outcome measure. Results Our results showed that the likelihood of incorrectly perceiving two ‘flashes’ at longer temporal delays increased with age and this was particularly evident for those with an increasing fall number trajectory. Furthermore, the likelihood of incorrectly perceiving two ‘flashes’ at the short temporal delay decreased with age but only for those same recurrent fallers. There was no association between longitudinal TUG trajectories and task performance. Conclusion Experiencing increasing incidents of falling over ten years is associated with distinct patterns of audio-visual integration in ageing. In contrast, long-term functional mobility is not. This may reflect links between multisensory integration and perturbed balance function and/or compromised cognitive functions (e.g. inhibitory control). Our findings contribute to our understanding of the mechanisms underpinning brain health in older age.