In a major new finding almost a decade in the making, researchers at Harvard Medical School say they’ve found a key that may unlock many of the mysteries of Alzheimer’s disease and brain aging — the humble metal lithium.

Lithium is a metal found in some foods, drinking water, and in trace amounts in our bodies. It has long been used to treat some psychiatric disorders. But its potential role in protection against brain aging and Alzheimer’s disease opens up new doors for developing medicines that may finally provide an effective tool for fighting this dreaded brain-robbing disease,

Researchers have discovered that naturally occurring lithium in the brain is depleted early in Alzheimer’s disease, especially in the prefrontal cortex, and that restoring physiological levels with lithium orotate in mice can prevent brain damage and memory loss.