Background: There is a poor understanding of the interplay between cognitive and physiological functions in leading to falls. We hypothesized that poorer physiological function would modify the effect of poorer cognitive function on increased risk of falling in older people.

Methods: A range of cognitive (executive function/attention, memory, processing speed, and visuospatial ability) and physiological functions (vision, proprioception, sway, leg strength, reaction time) were measured using standardized tests in 386 randomly selected adults aged 60–86. Incident falls were recorded over 12 months. Log-multinomial regression was used to model the relationships and test for interactions between cognition and physiological function in explaining the risk of single or multiple falls.

Results: Overall, 94 people (24.4%) had a single fall, and 78 (20.2%) had multiple falls. No significant associations were observed between cognitive function and the risk of single falls. The risk of multiple falls was increased with poorer function in Stroop dot time (RR = 1.03, 95% CI [1.01, 1.05], p = .002) and Stroop word time (RR = 1.02 [1.01, 1.03], p = .001) and reduced with better function in Category Fluency (RR = 0.94 [0.91, 0.98], p = .001) and visuospatial function (RR = 0.95 [0.92, 0.98], p < .001). These associations were amplified by the presence of greater body sway, less ambulatory physical activity, slower reaction time and gait speed, weaker muscle strength, and poorer visual contrast (p for interactions <.05).

Conclusions: Preventing falls due to physiological impairments in community-dwelling older people may need to be tailored based on cognitive impairment, a key factor in their inability to compensate for physical decline.