How cognitive loads modulate the postural control of older people with low back pain?

Background: PC is a strong risk factor for falling in older people, particularly in older individuals with low back pain (LBP). Cognitive involvement in postural control (PC) increases with age.However, most scholars have not considered different difficulty levels of cognitive loads when exploring the effects of cognition on PC in older patients with LBP. To investigate how different levels of cognitive loads modulate PC in older patients with LBP.Methods: This was a cross-sectional study. Twenty older women with LBP were recruited into the LBP group, and 20 healthy older women without the history of LBP were recruited into the healthy control (HC) group. Balance parameters were computed to quantify PC. All participants underwent the static balance test (SBT), which required the participant to maintain stability during standing on a force platform with or without a concurrent a cognitive task. The SBT included three levels of difficulties of posture tasks (eyes-open vs. eyes-closed vs. and one-leg stance) and three cognitive tasks (without cognitive task vs. auditory stimulation calculator task vs. serial-7s arithmetic task). Results: A repeated-measure analysis of variance (3 postural tasks × 3 congnitive tasks× 2 groups) testing the effects of the different congnitive task levels on the performance in different postural conditions.Older people with LBP had worse PC (as reflected by larger center of pressure (COP) parameters) than HCs regardless of postural or cognitive difficulties. Compared with the single task, the COP parameters of participants with LBP were larger during dual tasks, even though the difficulty level of the cognitive task was low. Larger COP parameters were shown only if the difficulty level of the cognitive task was high in HCs. Correlations between sway area/sway length and the number of falls were significant in dual tasks.Conclusion: Our findings shed light on the how cognitive loads modulate PC for older people with LBP. Compared with HCs, cognitive loads showed more disturbing effects on PC in older people with LBP, which was associated with falling.