The effect of diabetes on prefrontal cortex activation patterns during active walking in older adults

Background: Gait alterations were documented in diabetic patients. However, the effect of diabetes on cortical control of gait has not been reported. We evaluated the effect of diabetes on prefrontal cortex (PFC) Oxygenated Hemoglobin (HbO₂) levels during active walking in older adults. Methods: Of the total sample (n = 315; mean age = 76.84 ± 6.71ys; % female = 56.5) 43 participants (13.7%) had diabetes. The experimental paradigm consisted of two single tasks: Normal-Walk (NW); and Cognitive Interference (Alpha); and one dual-task condition consisting of the two single tasks, Walk-While-Talk (WWT). Functional Near-Infrared-Spectroscopy (fNIRS) was used to quantify PFC HbO₂ levels. Results: Older adults without diabetes showed higher PFC HbO₂ levels in WWT compared to both NW and Alpha. HbO₂ levels during NW were not different between the two groups. Consistent with Neural Inefficiency, older adults with diabetes exhibited higher HbO₂ levels during Alpha while performing significantly worse than those without diabetes. Moreover, the presence of diabetes was associated with attenuated HbO₂ levels during WWT. This pattern is consistent with Capacity Limitations suggesting a failure to recruit brain resources vis-à-vis the more cognitively challenging WWT condition. Conclusions: A distinct functional neural signature of diabetes was established during active and attention demanding walking among older adults without overt neurological disease.