Plasma selenium is positively related to performance in neurological tasks assessing coordination and motor speed

Abstract

Parkinson's disease (PD) is a degenerative process affecting the striato nigral system (SN). Its etiology, although obscure, may involve oxidative damage. Selenium, an antioxidant, was shown to protect the SN in animal models. In the current study, we investigate the association between plasma selenium concentrations and the presence of "soft" neurological signs related to the SN. Plasma selenium concentration was assessed in participants of age ≥65 years in the InCHIANTI study, a population-based cohort study in Tuscany, Italy. PD was defined based on standard criteria. "Soft" neurological signs were ascertained by physical examination. A total of 1,012 participants were included. No association was found between the presence of PD and plasma selenium. There was, however, a strong association between plasma selenium and timed performance-based assessments. Lower levels of selenium were significantly associated withdecreased performance in neurological tests of coordination among older adults. Prospective studies are needed to further investigate the effects of selenium on SN dysfunction.

Figure 1. Plasma selenium concentration by age*

*Note: Kernel-weighted local polynomial regression smoothing was used to generate this graph (red line = mean and shaded areas = 95% confidence intervals.

Figure 2

Figure 2a–c. Selected neuro-motor performance outcomes by plasma selenium concentration* *Note: Kernel-weighted local polynomial regression smoothing was used to generate the graphs (red line = mean and shaded areas = 95% confidence intervals. B coefficients were obtained from linear models regressing the neuro-motor performance outcome on selenium as a continuous variable adjusting for age, sex, total energy intake, MMSE score, and neuroleptic medication.