Recent experiments involving fruit flies, and low doses of lithium, resulted in a 16-18% increase in lifespan. However, higher doses of lithium resulted in an earlier death. Fruit flies share 75% of the genes that cause disease in human, which makes them an ideal test subject. The drug blocks activity of a molecule called glycogen synthase kinase-3 (GSK-3), which has been cited as a factor in the development of Alzheimer’s and Parkinson’s. Medical News Today has the story here.