Picture a sprig of rosemary or sage enhancing your roast chicken. Now, think about how these unassuming herbs might actually contribute to combating Alzheimer’s disease.
That’s right. Recent research has highlighted a compound named carnosic acid, which boasts impressive antioxidant and anti-inflammatory properties found in these kitchen favorites. Though carnosic acid is unstable in its natural form, scientists have ingeniously stabilized it into a prodrug called diAcCA. This allows it to effectively cross the blood-brain barrier, targeting damaged and inflamed brain cells. Although it’s still in the pre-clinical phase, this development brings a glimmer of hope that everyday herbs could potentially aid in slowing or even preventing cognitive decline.
What does the study say?
A study published in the journal Antioxidants from researchers at the Scripps Research Institute found that carnosic acid, present in rosemary and sage, possesses remarkable properties that could aid in fighting neurodegenerative diseases like Alzheimer’s. Researchers Piu Banerjee and Dr. Stuart Lipton communicated their findings. They mentioned that administering this compound to mice with advanced Alzheimer’s-like conditions significantly boosted both neuron count and the connections between brain cells. Furthermore, it seemed to alleviate inflammation caused by existing anti-amyloid treatments, enhancing learning and memory abilities in the treated mice.
Banerjee elaborated that carnosic acid is termed a “prodrug,” meaning it remains inactive until it enters the body, becoming activated in response to oxidative and inflammatory stress. “It targets cells under such stress without harming healthy brain tissues,” she remarked, making it a safer treatment option. Nonetheless, the researchers caution that while the evidence from mice is promising, human studies are crucial for a complete understanding. Courtney Kloske from the Alzheimer’s Association emphasized the importance of further research to evaluate how these compounds might affect humans at risk for or living with Alzheimer’s.
They also clarified that simply cooking with rosemary or sage won’t yield the same anti-inflammatory effects. Banerjee noted that achieving the medicinal benefits seen with the new drug would require more herbs than can be safely consumed. Kloske advised against using these herbs or carnosic acid as a preventive or treatment measure for Alzheimer’s or other cognitive difficulties.
Origins and key compound: Carnosic acid in rosemary and sage
Both rosemary (Rosmarinus officinalis) and sage carry historical significance—ancient scholars believed rosemary aided memory retention. Modern studies support that carnosic acid, along with other compounds, offers strong antioxidant and anti-inflammatory effects that can extend to the brain. These compounds activate the Nrf2 pathway, boosting the production of enzymes that counter oxidative stress, a major contributor to Alzheimer’s.
From kitchen to lab: Creating diAcCA
The inherent instability of carnosic acid posed challenges for its therapeutic application, until researchers at Scripps developed diAcCA, a more stable acetylated prodrug. When ingested, diAcCA converts to its active form in the gut, enabling it to enter the bloodstream and reach the brain. In mouse models that simulate Alzheimer’s (5xFAD strain), treatment with diAcCA over three months restored memory and learning to nearly normal levels, increased synaptic density, and reduced neuroinflammation and amyloid-β and phosphorylated tau buildup.
The results were consistently observed across various tasks, yielding no toxicity among participants.
Mechanisms at work: A multi-front attack
diAcCA—and its active form, carnosic acid—seems to tackle Alzheimer’s through various synergistic approaches:
- Antioxidant defense: Activates Nrf2, promoting gene expression that addresses oxidative stress and stabilizes cellular balance.
- Anti-inflammatory action: Inhibits cytokine release and inflammasome activation, decreasing detrimental microglial activity.
- Neurotrophic support: Enhances nerve growth factor, BDNF, and synaptic resilience.
- Cholinergic enhancement: Rosemary’s 1,8-cineole impedes acetylcholinesterase, helping maintain necessary acetylcholine levels for memory function.
- Reduced neurotoxic proteins: Facilitates the clearance of amyloid-β and tau aggregates through synaptic and inflammatory pathways.
The future ahead:
Although diAcCA hasn’t yet been trialed in humans, several promising indications are emerging. The FDA classifies carnosic acid as “Generally Recognized as Safe,” which may facilitate initial trials. Animal studies indicate that diAcCA is well tolerated and could also aid the digestive system, while smaller human trials using rosemary or sage extracts have shown improvements in cognitive speed and memory in older adults. Meta-analyses of animal research suggest moderate to strong cognitive benefits from rosemary extract.
Banerjee expressed hope regarding future developments, stating, “I hope our drug will begin human clinical trials soon. If effective, it could be a significant new medication for Alzheimer’s patients. We remain cautiously optimistic about its prospects in human trials!”
