Safety and Target Engagement of Centella asiatica in Cognitive Impairment

Background of the study

Centella asiatica is a popular plant-based dietary supplement sold in the U.S. as “gotu kola” with potential to be developed into a botanical drug. The herb reportedly enhances memory and cognitive function, although little is known about how it does so.

Dr. Amala Soumyanath and neurologist Dr. Joseph Quinn, in collaboration with neuroscientists and analytical experts, are studying the potential use of Centella asiatica for neurological diseases, including Alzheimer’s disease. Their research has shown that administration of Centella asiatica extract improves cognition in aged mice and in genetically engineered Alzheimer’s-like mice. In addition, the team administered Centella asiatica extract to mouse and human brain cells grown in laboratory dishes to study its biological mechanisms and they believe that Centella asiatica reduces oxidative stress (or damage from toxic molecules called reactive oxygen radicals) and increases the function of mitochondria, components of cells that generate energy, in these models. Since oxidative stress and mitochondrial dysfunction appear to play a role in Alzheimer’s disease and mild cognitive impairment ((MCI), a subtle decline in memory that may precede Alzheimer’s), the Centella extract may be able to positively impact biology relevant to Alzheimer’s. In the upcoming clinical trial, Dr. Soumyanath and colleagues will now study whether Centella asiatica affects oxidative stress and mitochondria in individuals treated with a Centella product, as the basis for future research examining its effects on cognition.

Research study

Dr. Soumyanath and colleagues will conduct a Phase I clinical research study to explore the safety and biological activity of Centella asiatica in people with MCI or mild Alzheimer’s. They will recruit 48 individuals aged 65–85 years diagnosed with MCI or mild Alzheimer’s. They will randomly assign half to take a Centella asiatica product and half to take a placebo. A placebo is not the actual Centella product but an inactive substance that has no known risk for the participant. Neither the individuals nor the investigators will know to which product participants have been assigned until completion of the study. The individuals will take either Centella product or a placebo for six weeks, with evaluations throughout the study and for four weeks after the last dose.

The researchers will use a specialized brain scan technique called magnetic resonance spectroscopic imaging (1H-MRSI and 31P-MRSI) to measure levels of specific molecules in the brain that indicate healthy nerve cells and their mitochondrial activity. In addition, the research team will measure levels of molecules suggestive of disease progression and oxidative stress in participants’ blood and urine. Finally, the researchers will study the safety and tolerability of the Centella product and investigate any negative side effects.


older man smiling outdoors

The ultimate goal of the researchers is to produce a therapeutic from Centella asiatica for use in MCI and Alzheimer’s. This research study investigates a Centella product’s safety and potential beneficial effects on the brain when administered for a relatively short period of 6 weeks. If successful, this study will lead to a larger and longer Phase II efficacy study of Centella asiatica’s effects on cognition in individuals with MCI and Alzheimer’s.


Principle Investigator: Dr. Amala Soumyanath – Professor of Neurology, School of Medicine, Director of the NIH funded BENFRA Botanical Dietary Supplements Research Center at OHSU, and Co-Director of the NIH T32 Training Grant on CAM Research Training in Neuroscience and Stress.

Co-Investigator: Dr. Joseph Quinn – Professor of Neurology, School of Medicine, Director, OHSU Parkinson Center and Movement Disorders Program, School of Medicine, Director, Portland VAMC Parkinson’s Disease Research, Education, and Clinical Center (PADRECC), Wayne and Sandra Ericksen Professorship for Neurodegenerative Research, Neuroscience Graduate Program, School of Medicine.


Please contact us for more information at 503-418-8197 or

Study title: Safety and Target Engagement of Centella asiatica in Cognitive Impairment
IRB protocol # 17767;

Principal Investigator: Dr. Amala Soumyanath and Co-Investigator: Dr. Joseph Quinn