The effect of fear of falling on prefrontal cortex activation and efficiency during walking in older adults.

Neural inefficiency is inferred when higher brain activations are associated with similar or worse performance. Improved neural efficiency is achieved when task-related brain activations are reduced after practice. No information is available on the effect of fear-of-falling (FOF) on brain activation during walking. We hypothesized that the presence of FOF would be associated with neural inefficiency and with a delay in improving neural efficiency during dual-task walking. Task conditions included single-task walk (STW), Alpha (cognitive interference), and dual-task walk (DTW). Functional near-infrared spectroscopy (fNIRS)-derived HbO in the prefrontal cortex (PFC) was used to quantify task-related changes in brain activation. Practice included three repeated counterbalanced trials for each task. Participants with FOF (n = 19; mean age = 79.84 ± 6.01 years; %female = 68.42) and without FOF (n = 56; mean age = 76.73 ± 6.39 years; %female = 44.64) were included. The presence of FOF was associated with slower stride velocity (estimate = - 12.354; p = 0.0154) and with greater increases in PFC HbO from STW to DTW (estimate = 0.303, p = 0.0009) and from Alpha to DTW (estimate = 0.387, p < 0.0001). Compared to controls, participants reporting FOF demonstrated an attenuated decline in PFC HbO from the first to the second DTW trials (estimate = 0.264; p = 0.0173). In contrast, compared to controls, participants with FOF demonstrated greater decline in Alpha PFC HbO from trial 1 to trial 2 (estimate = - 0.419, p < 0.0001) and from trial 1 to 3 (estimate = - 0.281, p = 0.0006). The change in PFC HbO over repeated STW trials was not significant and was not moderated by FOF status. The presence of FOF was associated with higher and inefficient PFC activation during DTW in older adults.