Background: Walking speed is a practical measure of motor function and physical performance in older adults and has been considered as an informative “vital sign”. Cadmium exposure, even at low environmental levels, are associated with neurologic, vascular, and cognitive dysfunction, which may be connected with motor function decline. We investigated the associations of cadmium concentrations in blood and urine with walking speed in in the US general population.
Methods: The study participants included 3,787 adults aged ≥50 years from the National Health and Nutrition Examination Survey 1999-2002, who had determinations of cadmium concentrations in blood or in urine, and who had measurements of walking speed. We calculated walking speed (ft/sec) as walked distance (20 ft) divided by time to walk (second).
Results: The weighted geometric means of cadmium concentrations in blood and urine were 0.49 [95% confidence interval (CI): 0.47-0.52] µg/L and 0.37 (95% CI: 0.34-0.42) ng/mL, respectively. The highest (vs. lowest) quintile of blood cadmium was associated with 0.18 (95% CI: 0.10, 0.25) ft/sec reduction in walking speed (P-trend <0.001) after adjusting for sociodemographic, anthropometric, health-related behavioral, and clinical risk factors and biomarkers for inflammation. However, no association was observed for urine cadmium levels with walking speed.
Conclusions: We found that the cadmium concentrations in blood, but not in urine, were associated with a reduced walking speed. Our findings suggest that cadmium toxicity even at low levels of environmental exposure contribute to motor function decline in the general population.