A natural compound found in herbs like rosemary and sage may hold new hope for people with Alzheimer’s disease.
Researchers at Scripps Research have developed a more stable version of this compound, called diAcCA, and found that it improves memory and reduces brain damage in mice with Alzheimer’s. The findings, published in Antioxidants, could lead to a new class of safe and effective treatments for this devastating condition.
Alzheimer’s disease is the most common cause of dementia and the sixth-leading cause of death in the United States. One of its key drivers is chronic inflammation in the brain, which leads to memory loss and the breakdown of connections between brain cells (called synapses).
Scientists have long been interested in the herb rosemary for its potential memory-boosting properties. Even Shakespeare’s Ophelia mentioned, “There’s rosemary, that’s for remembrance.”
The key compound in rosemary and sage is carnosic acid, a powerful antioxidant and anti-inflammatory. It activates the body’s natural defense system by turning on protective enzymes. However, carnosic acid is unstable, which makes it unsuitable for drug development. It breaks down quickly when exposed to air or stored over time.
To solve this, the Scripps team created diAcCA, a stable form of carnosic acid that only activates inside the body. Once ingested, diAcCA turns into carnosic acid in the gut and then enters the bloodstream.
In mouse models of Alzheimer’s, the researchers found that this compound not only reached the brain in effective amounts, but also led to clear improvements in memory and increased synaptic density—meaning more healthy connections between brain cells.
Dr. Stuart Lipton, the lead author and a neurologist at Scripps, explained that diAcCA has a unique advantage: it only becomes active in areas of the brain that are inflamed. That means it targets damaged areas without affecting healthy tissue, helping to limit side effects. Carnosic acid is already considered safe by the FDA, which could help speed up the path to human trials.
The team found that mice treated with diAcCA performed significantly better in memory tests than untreated mice. In fact, the memory performance of treated mice returned nearly to normal.
When researchers looked at the brain tissue under the microscope, they saw more synapses, less inflammation, and fewer harmful protein clumps like phosphorylated tau and amyloid-beta plaques—hallmarks of Alzheimer’s disease.
They also found that mice absorbed about 20% more carnosic acid from diAcCA than they did from taking carnosic acid directly. Because carnosic acid degrades quickly in storage and during digestion, the new form—diAcCA—delivers more of the beneficial compound where it’s needed.
Importantly, the mice showed no signs of toxicity. In fact, diAcCA helped reduce baseline inflammation in the digestive system, suggesting additional health benefits.
Lipton believes diAcCA could also work alongside existing Alzheimer’s drugs. Treatments like amyloid-targeting antibodies can sometimes cause dangerous side effects such as brain swelling or bleeding. DiAcCA might help reduce or prevent these side effects by calming inflammation, potentially making those therapies safer and more effective.
Looking ahead, Lipton is hopeful that because diAcCA is derived from a GRAS (generally regarded as safe) compound and has shown no toxic effects in animals, it could be fast-tracked into clinical trials.
He also sees potential for using it to treat other inflammation-related conditions like type 2 diabetes, heart disease, and neurodegenerative disorders such as Parkinson’s disease.
Review and Analysis
This study highlights the power of combining natural compounds with modern chemistry to create new treatments. While carnosic acid from rosemary and sage has long been linked with brain health, this is the first time a stable version has shown such strong effects in a living model of Alzheimer’s.
What makes diAcCA particularly exciting is its targeted activity—it turns on only in inflamed parts of the brain. That could reduce side effects, a major hurdle in Alzheimer’s treatment. The improvements in memory and brain structure, along with the safety data, are impressive for a preclinical study.
Still, it’s important to remember that this research was conducted in mice. Human trials are needed to confirm safety and effectiveness in people. But the compound’s natural origin and established safety profile give it a strong advantage for future testing.
In short, rosemary’s memory-boosting reputation may have a real scientific foundation—and it might just lead to one of the next big breakthroughs in Alzheimer’s care.
If you care about brain health, please read studies about vitamin D deficiency linked to Alzheimer’s and vascular dementia, and blood pressure problem at night may increase Alzheimer’s risk.
For more information about brain health, please see recent studies about antioxidants that could help reduce dementia risk, and epilepsy drug may help treat Alzheimer’s disease.
The research findings can be found in Antioxidants.
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