The document describes a randomized clinical trial that investigated the effects of long-term low-dose lithium treatment in older adults with amnestic mild cognitive impairment. 61 participants were randomly assigned to receive either lithium or placebo treatment for 2 years, followed by a 2-year extension phase without blinding. The primary outcomes were changes in cognitive and functional scores after 2 years. Secondary outcomes included neuropsychological tests, CSF biomarkers, and conversion to dementia. Results showed that the lithium and placebo groups were similar at baseline on sociodemographic, clinical, and biological measures.