Affiliations: [a] Department of Chemistry, University of Missouri, Columbia, MO, USA | [b] University of Missouri Research Reactor, University of Missouri, Columbia, MO, USA | [c] Departments of Pathology and Neurology, University of Kentucky, Lexington, KY, USA | [d] Sanders-Brown Center on Aging and Alzheimer's Disease Center, University of Kentucky, Lexington, KY, USA | [e] Department of Chemistry, University of Kentucky, Lexington, KY, USA
Correspondence:
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Corresponding author: Mark A. Lovell, University of Kentucky, 135 Sanders-Brown Building, 800 S. Limestone St., Lexington, KY 40536, USA. E-mail: malove2@email.uky.edu.
Abstract: Previous studies show significantly decreased levels of zinc transporter 1 (ZnT-1) in the brain of subjects with mild cognitive impairment (MCI) but significantly increased ZnT-1 in late stage AD (LAD). However, the reason for the apparent dichotomy is unclear. Based on in vivo studies that show animals provided a zinc (Zn) deficient diet demonstrate decreased brain ZnT-1, we used inductively coupled plasma-mass spectrometry (ICP-MS) to quantify serum Zn levels from 18 living mild to moderate AD patients (9 men, 9 women), 19 MCI patients (9 men, 10 women) and 16 age-matched normal control (NC) subjects (9 men, 7 women). Zinc levels for all subjects were not significantly different among any of the three subject groups. However, there was a statistically significant decrease of serum Zn (11.7 ± 0.5 μM) in men with MCI compared to women with MCI (13.7 ± 0.6 μM) and NC men (13.9 ± 0.6 μM). Serum Zn levels in probable AD patients were comparable to those in NC subjects. Overall, these data suggest a significant decrease of serum Zn in men with MCI, may explain the loss of ZnT-1 observed in previous studies and suggest there may be more pronounced sex differences in MCI than were previously recognized.
