A compound derived from rosemary and sage, long associated with memory, may offer new hope in the fight against Alzheimer’s disease.
Researchers at Scripps Research have developed a stable version of carnosic acid, a natural anti-inflammatory and antioxidant compound, and found that it improved memory, reduced brain inflammation, and restored synaptic density in mouse models of Alzheimer’s.
The new compound, named diAcCA, was described in a study published February 28, 2025, in Antioxidants. When taken orally, diAcCA is converted in the gut to carnosic acid, which then enters the bloodstream and reaches the brain.
There, it activates the body’s natural defense pathways, reducing inflammation and oxidative stress—two key contributors to neurodegeneration in Alzheimer’s disease.
“By combating inflammation and oxidative stress with this diAcCA compound, we actually increased the number of synapses in the brain,” said senior author Dr. Stuart Lipton, a neurologist and professor at Scripps Research. “It didn’t just slow the decline—it improved memory virtually back to normal.”
Carnosic acid, found in rosemary and sage, is known to activate the Nrf2 pathway, which boosts the production of protective antioxidant and anti-inflammatory proteins. But the natural form of the compound breaks down too easily to be used as a reliable medication.
That’s why Lipton and chemistry expert Dr. Phil Baran created diAcCA—a stable derivative that stores well and remains intact until it reaches the body, where it is converted into active carnosic acid.
Once in the brain, diAcCA targets areas with high inflammation, becoming active only where needed. This selectivity may limit side effects, a key advantage over other treatments. The compound is also related to substances already recognized as safe by the FDA, which may help speed up clinical trials.
In the study, mice genetically modified to develop Alzheimer’s-like symptoms were treated with diAcCA for three months. The researchers found:
- Improved performance in multiple memory and learning tests
- Increased synaptic density, or more connections between nerve cells
- Reduced brain inflammation
- Lower levels of toxic proteins, including phosphorylated tau and amyloid-β plaques, both of which are hallmarks of Alzheimer’s
Tissue samples also showed a 20% increase in carnosic acid uptake when the mice received diAcCA compared to plain carnosic acid, making the drug more effective. Toxicity studies found that diAcCA was well tolerated, and it even reduced inflammation in the stomach and esophagus.
Dr. Lipton believes diAcCA could be used not only as a standalone treatment, but also in combination with existing Alzheimer’s drugs, particularly amyloid antibody treatments, which can cause serious side effects like brain swelling and bleeding. DiAcCA’s anti-inflammatory effects may reduce these risks, making other therapies safer and more effective.
A clinical trial has not yet begun, but Lipton is optimistic that diAcCA could be fast-tracked for human studies due to its strong safety profile and therapeutic promise. Beyond Alzheimer’s, the compound could potentially be explored for treating other inflammatory diseases, including type 2 diabetes, heart disease, Parkinson’s disease, and other forms of neurodegeneration.
In the spirit of Ophelia’s famous line in Hamlet, “There’s rosemary, that’s for remembrance,” this centuries-old herb may soon play a very modern role in protecting and restoring memory—this time, with science to back it up.
If you care about Alzheimer’s, please read studies about the likely cause of Alzheimer’s disease, and new non-drug treatment that could help prevent Alzheimer’s.
For more information about brain health, please see recent studies about diet that may help prevent Alzheimer’s, and results showing some dementia cases could be prevented by changing these 12 things.
The research findings can be found in Antioxidants.
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