South African Medical Journal

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Zinc and platelet membrane microviscosity in Alzheimer's disease: The in vivo effect of zinc on platelet membranes and cognition

Felix C.V. Potocnik, Susan J. van Rensburg, Caron Park, Joshua J.F. Taljaard, Robin A. Emsley


Objectives. To investigate the effects of oral zinc supplementation on: (i) plasma zinc concentrations; (ii) platelet membrane microviscosity in vivo; and (iii) cognitive function of Alzheimer's disease (AD) patients.

Design. An open-labelled pilot study.

Setting. University of Stellenbosch Medical School and Stikland Hospital.

Subjects. Six volunteer AD patients.

Outcome measures. Plasma zinc levels, platelet membrane microviscosity and cognition (MMSE and ADAS-cog tests).

Results. Oral zinc supplementation (30 mg/day) did not increase plasma zinc levels significantly, but signfficantly increased platelet membrane microviscosity (P = 0.02; 6 patients). Four patients. who underwent 12 months of evaluation, showed modest cognitive improvement on psychomebic testing (Mini-Mental State Examination and the cognitive portion of the Alzheimer's Disease Assessment scale scores).

Conclusions. While earlier literature promoted the use of zinc in AD patients, a recent study has contradicted this and implicated zinc in the aetiology of Alzheimer's disease. On the basis of the above resutts, it may be premature to single out zinc as a causal agent in AD.

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