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study on the skin cancer drug Targretin was found to have reversed signs and symptoms of Alzheimer’s disease in the mice.

Six hours after mice got the drug, they began performing better in tests, became more social and even regained their sense of smell, which is commonly lost in Alzheimer's. These effect were said to have lasted up to three days.
The next step for researchers is to see if the medicine has similar benefits in humans. Clinical trials for humans are being designed and should produce early results in the coming year, the researchers said.