Association of Parkinson's disease with altered serum levels of lead and transition metals among South Indian subjects.

Several epidemiologic studies have suggested an association between the Parkinson's disease (PD) and exposure to heavy metals, such as lead, iron, copper, manganese, etc. A growing body of evidence suggests that heavy metals stimulate free radical formation in the brain and can lead to neurodegeneration. In the present study, we investigated whether such association exists in PD cases from rural and urban areas in our study population. The plasma levels of copper, iron, manganese and lead in PD cases (n = 150) and controls (n = 170) were determined by inductively coupled plasma mass spectrometry (ICP-MS) and correlated with the oxidative stress markers like malondialdehyde (MDA), protein carbonyl and total glutathione. Results indicated significant increase in the levels of copper (17.73 +/- 4.48 vs. 13.0 + 3.22 ng/ml) and iron (554.4 +/- 123.8 vs. 421.7 +/- 126.1 ng/ml) in PD cases compared to controls, whereas no significant differences in the levels of manganese and lead were observed. Further, the data based on urban or rural residence showed that plasma copper, iron, manganese levels were comparatively higher in rural subjects, whereas plasma lead levels were significantly higher in urban subjects. Increased plasma iron showed positive correlation with marker of lipid peroxidation (MDA), suggesting that increased iron levels induced oxidative stress in PD. These results substantiated the earlier observations about the role of environmental exposure and metal-induced oxidative stress in the etiology of PD.