A 2003 study evaluated the safety and efficacy of using extract from culinary sage (Salvia officinalis) to treat patients with mild-moderate Alzheimer's. Patients were given either 60 drops/day of sage extract or a placebo for a period of 4 months. At the conclusion of the trial, the extract produced significant cognitive improvements compared to the placebo. Those taking the extract also showed less agitation than those on the placebo. No significant side-effects were noted.
Another trial using the same variety of sage was conducted in 2006. This time, researchers looked at using sage extract and one of its components, rosmarinic acid, to treat Alzheimer's in rats. Both sage extract and rosmarinic acid were found to reduce Alzheimer's-related cell death. The acid was also found to reduce the production of reactive oxygen species, the formation of harmful tau protein tangles, and damage to DNA. While this makes a case for rosmarinic acid being an important part of sage's ability to fight Alzheimer's, the authors note that there are likely other compounds in sage that also contribute to its effects.
Clinical trials using sage to treat Alzheimer's are ongoing.