This trial aims to test the hypothesis that 1) a single dose of zinc cysteine in a proprietary gastro-retentive form will produce sustained blood levels of zinc giving a larger bioavailable amount of zinc than an FDA approved preparation of inorganic zinc acetate; and 2) that the zinc cysteine gastro-retentive, sustained-release preparation will be better tolerated with significantly less gastrointestinal side effects than the zinc acetate capsules. The trial also tests the hypothesis that, after 6 months of once daily administration, the zinc cysteine subjects will show reduced serum non-ceruloplasmin copper. Additionally, subjects will perform tests of mental function,including the dementia rating scale, the Mini Mental Status Examination and the ADAS-cognitive performance test aimed at Alzheimer's status assessment. Tests will be administered at baseline, 3 and 6 months, and the performance results compared. Care-giver assessments will also be noted.