Correlations among heavy metals in blood and urine and their relations to depressive symptoms in Parkinson's disease patients

OBJECTIVES: From our previous results, manganese (Mn) and iron (Fe) in the blood of Parkinson's disease (PD) patients without depression were higher than those of both the PD patients with depression and controls, the hypothesis that "two types of PD exist-PD without depression and affected by Mn and Fe, and PD with depression and unaffected by Mn or Fe" was induced. To investigate the hypothesis, correlations among blood and urine metals were compared in the subjects.

METHODS: Subjects comprised PD patients with depression, PD patients without depression and controls recruited from an outpatient clinic in China. Morning blood and urine samples were used to measure concentrations of metals.

RESULTS: In the controls, Mn, Fe and zinc (Zn) levels in blood strongly correlated with each other. The correlation coefficient between Mn and Zn in blood was significant in the PD patients with depression and the controls, but not in the PD patients without depression. Correlations of Fe between blood and urine in the PD patients without depression were significant, but not in the PD patients with depression and the controls.

CONCLUSIONS: A common route of simultaneous intake of Mn, Fe and Zn could exist in our subjects, however in PD patients without depression, a large intake of Mn may have been from another route. Some results of the PD patients without depression were different from those of the PD patients with depression and the controls. Thus, two types of PD may exist.