Intriguing research presented in July hints that lithium, a common treatment for bipolar disorder, may help rid the brain of plaques and tangles, two hallmarks of Alzheimer's disease.In a study of 74 elderly people with bipolar disorder, four percent of those taking lithium had Alzheimer's disease, compared with 21 percent of the participants who were not taking the drug.

The Brazilian team believes that lithium works by blocking the action of an enzyme called GSK-3.

Drug companies are working on developing lithium-like drugs that inhibit the enzyme but are free of the side effects sometimes noted with long-term lithium therapy.