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08-02-2011 | Mental health | Article

Certain toxic trace elements may be elevated in bipolar disorder

Abstract

Free abstract

MedWire News: Results from a Spanish study suggest that patients with bipolar disorder have elevated levels of some toxic trace elements.

"Essential trace elements such as copper or zinc are required at optimum concentration for the proper functioning of the human biological system," explain Montserrat González-Estecha (Hospital Clínico San Carlos, Madrid) and team. "A deficiency can cause various metabolic disorders while high levels are toxic."

They add: "Although pivotal biochemical alterations underlying neuropsychiatric disorders are unknown, changes in trace elements may play an important role.

"However, we have limited information on the concentrations of trace elements in serum of individuals with bipolar mood disorders."

To investigate further, the team recruited 25 patients with bipolar disorder who were aged an average of 49.9 years and 29 age-, gender-, and education-matched mentally healthy controls.

Blood and urine samples were collected from the participants and analyzed for concentrations of copper, zinc, lead, cadmium, and thallium.

The researchers found that median serum levels of lead and cadmium were significantly higher in bipolar patients than controls, at 3.00 versus 2.20 µg/dl, and 0.39 versus 0.10 µg/l, respectively. Median urine levels of these metals were also significantly higher in patients than controls, at 1.50 versus 0.80 µg/g creatinine (Cr), and 0.25 versus 0.11 µg/g Cr, respectively.

Patients with bipolar disorder also had higher mean serum zinc levels than controls, at 107.92 versus 86.07 µg/dl, as well as higher median urine levels of thallium, at 0.14 versus 0.08 µg/g Cr.

Further analysis showed that bipolar patients who were experiencing an episode of mania had significantly higher serum zinc levels than controls, at a mean of 111.28 versus 86.07 µg/dl, but there were no significant differences in serum zinc levels between bipolar patients who were experiencing an episode of depression and controls.

The team also notes that, in bipolar patients, median serum levels of cadmium were significantly higher in smokers than nonsmokers, at 1.20 versus 0.12 µg/l, respectively.

There was no significant difference in serum copper levels between bipolar patients and controls.

González-Estecha and team conclude in the Journal of Trace Elements in Medicine and Biology: "The results suggest that there could be higher levels of some toxic trace elements in the group of patients with bipolar disorder than in the healthy control group."

They add: "The results obtained in our study suggest the need to confirm these findings in future studies with a different design and much greater sample size, which would allow the clarification of the role that these and other trace elements may play in bipolar disorder."

MedWire (www.medwire-news.md) is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Mark Cowen

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