Recent studies have shown that lithium may block the accumulation of amyloid-beta (Abeta) peptides and to inhibit the hyperphosphorylation of tau via the inhibition of GSK-3alpha in the brain of mice. The purpose of the present study is to examine whether lithium could potentially be effective for the prevention of Alzheimer's disease. We investigated the clinical records of 1,423 outpatients at a university psychiatric outpatient clinic and classified patients according to the following criteria: (a) absence of a diagnosis of dementia, (b) age 60 years or older, and (c) lithium had been prescribed and/or was currently prescribed. We compared these patients with randomly selected age and gender matched control group who had never been prescribed lithium. Despite no significant difference in MMSE scores between the lithium group, which consisted of patients receiving lithium treatment, and the control group, those who had previously received lithium and/or were currently prescribed lithium had significantly better MMSE scores than the control patients. The findings provide partial evidence to support the contention that lithium could offer hope as a preventive treatment for Alzheimer's disease. Further prospective studies with a large number of patients are warranted to investigate this potentially important effect.