Researchers at Harvard Medical School in Boston now say that lithium could help treat the 7 million people with Alzheimer's disease.

A few limited clinical trials of lithium for Alzheimer’s disease have shown some efficacy, but the lithium compounds they used — such as the clinical standard, lithium carbonate — can be toxic to aging people at the high doses normally used in the clinic.

Years of investigation by scientists at Harvard has revealed that lithium is deeply involved in Alzheimer’s disease, a finding that could lead to new treatments.