A drug brought to light by Hippocrates in the 5th century BC could help restore memory in Alzheimer's patients, scientists hope.
Salsalate, which comes from the same family as aspirin, was typically used to treat inflammatory conditions such as rheumatoid arthritis.
But a new study suggests it can prevent the build-up of toxic proteins in the brain and even reverse damage already done, unblocking pathways and restoring memory.
Trials limited to mice could soon include humans because researchers know the drug is safe and produces few side-effects.
Scientists in the United States say it is the first time a drug has been shown to reverse all toxic effects of defective tau proteins in the brain.
The proteins accumulate in people with dementia, driving degeneration and mental decline. But a low dose of salsalate appears to lower tau levels, "rescuing" memories and protecting the hippocampus, a part of the brain essential for memory formation".
"We identified for the first time a pharmacological approach that reverses all aspects of tau toxicity," said Dr Li Gan, of the Gladstone Institutes, University of California.
The Greek physician Hippocrates first described salicylates as a bitter powder extract from willow bark that eased pain and reduced fevers.
The research was published in the journal Nature Medicine.