SLC30A3 and Alzheimer disease: Knocking down ZnT3 in mice leads to cognitive difficulties occurring earlier than expected.149 An interesting discovery revealed a decline in ZnT3 levels in the brains of mice and humans with aging; however, an even more significant reduction was observed in AD patients.544 Despite the downregulation of ZnT3, compensatory upregulations of ZnT4, ZnT6, and ZnT1 were observed in the hippocampus of AD.545,546