Altered visual-spatial attention to task-irrelevant information is associated with falls risk in older adults

Abstract

Executive cognitive functions play a critical role in falls risk—a pressing health care issue in seniors. In particular, intact attentional processing is integral for safe mobility and navigation. However, the specific contribution of impaired visual–spatial attention in falls remains unclear. In this study, we examined the association between visual–spatial attention to task-irrelevant stimuli and falls risk in community-dwelling older adults. Participants completed a visual target discrimination task at fixation while task-irrelevant probes were presented in both visual fields. We assessed attention to left and right peripheral probes using event-related potentials (ERPs). Falls risk was determined using the valid and reliable Physiological Profile Assessment (PPA). We found a significantly positive association between reduced attentional facilitation, as measured by the N1 ERP component, and falls risk. This relationship was specific to probes presented in the left visual field and measured at ipsilateral electrode sites. Our results suggest that fallers exhibit reduced attention to the left side of visual space and provide evidence that impaired right hemispheric function and/or structure may contribute to falls.

Figures

Figure 1

Stimulus presentation and timing for the target discrimination task at fixation, with task-irrelevant probes presented in the left and right periphery.

Figure 2

ERP waveforms for the P1 and N1 components, time-locked to task-irrelevant probes, as a function of load (high versus low) and visual field presentation (left versus right). Larger N1 amplitude (i.e., more negative) was significantly associated with lower falls risk for left visual field probes measured at OL+.

Figure 3

Significant correlations between mean ERP amplitudes (uV) and falls risk for (a) the N1 for stimuli presented in the left visual field, measured at ipsilateral sites (OL+) and (b) for the P300 for targets presented at fixation during low load blocks.

Figure 3

Significant correlations between mean ERP amplitudes (uV) and falls risk for (a) the N1 for stimuli presented in the left visual field, measured at ipsilateral sites (OL+) and (b) for the P300 for targets presented at fixation during low load blocks.

Figure 4

ERP waveforms for the P300 component, time-locked to central targets and non-targets, as a function of load (high versus low) and trial type (targets versus non-targets). P300 amplitude was largest measured at the PZ electrode site, and for targets appearing in low load blocks.