Evidence of functional zinc deficiency in Parkinson's disease

One of the primary areas of investigation in the pathophysiology of Parkinson's disease (PD) is the loss of the dopamine-producing cells in the melanized neurons of the substantia nigra, believed to be caused by oxidative stress resulting from excessive free radical activity. The cuprozinc enzyme, superoxide dismutase (SODCu2Zn2), catalyzes the dismutation of superoxide anions to hydrogen peroxide plus oxygen, and is normally found in high concentrations in the substantia nigra where it protects neurons by scavenging free radicals. Zinc supplementation has been shown to significantly increase SODCu2Zn2 in vitro. A novel oral zinc tally test (ZTT) used in the assessment of zinc status was administered to 100 PD patients and 25 controls. Patients with PD showed a significantly decreased zinc status as compared to controls (p < 0.001). Significance was also established for 3 self-reported health-related variables thought to be related to zinc status: vision problems, olfactory loss, and taste loss (p < 0.05). Relative risks for patients with PD for these variables were 1.51, 1.56, and 1.33, respectively. Zinc status as measured by the ZTT is negatively correlated with PD status. PD status is positively correlated with self-reported vision problems, and olfactory and taste loss. Further study of the role of zinc in the development and treatment of PD is warranted.