Study applies scientific rigor to herbal supplement purported to improve memory, delay dementia

Dietary supplements line store shelves, and some plants used in these supplements have been consumed for millennia to cure a variety of human ills. Yet, consumers seeking relief for health conditions and diseases may wonder if they’re truly effective.

Starting with a botanical used in dietary supplements that’s purported to improve memory, a new clinical trial underway at Oregon Health & Science University will try to find out.

OHSU is recruiting people ages 65 to 85 who have been diagnosed with mild cases of Alzheimer’s disease or cognitive impairment for a pilot study testing a carefully formulated extract of the herb Gotu kola (Centella asiatica). The study is focused on the herb’s reported benefits in improving memory and forestalling cognitive decline. The trial isn’t testing memory directly; rather, researchers are looking for a signal, or biomarker, in blood samples and in brain imaging studies that may indicate an ability of Gotu kola to improve memory.

It marks the first clinical trial to test a botanical used in dietary supplements since the OHSU Botanical Dietary Supplements Research Center was established in 2020, although the trial is based on extensive foundational research conducted even before the center was established.

Andrew Clark, 83, of Pendleton said he was happy to come all the way from Eastern Oregon to participate in the trial.

“As I’m going down this path of dementia, it isn’t a very happy trip,” he said. “But if we can learn anything from my case that will lead to something like prevention or mitigation of dementia in other people to make their path easier or happier than mine, that will be good.”

As with all participants, he has a 50% chance that he was given an inert placebo and not the formulated Centella extract. And Clark says he’s fine with that. A former State Veterinarian for Oregon with a background in science, he fully understands that double-blind randomized controlled trials are the gold standard of research.

Clark, who writes a column for the East Oregonian newspaper, knows that whatever he consumed will help to apply scientific rigor to a popular dietary supplement. Gotu kola is marketed as a memory booster, in addition to other indications involving treatment of wounds and easing symptoms from psoriasis, a skin condition.

“I am very happy to be a lab rat,” he quipped.

Investigating botanicals

Clark is among the first participants in the trial, which involved a substantial amount of preclinical research years before he enrolled in the spring of 2023.

OHSU investigators conducted preclinical experiments and early human pharmacokinetics studies in collaboration with Oregon State University and Redmond-based herbal supplements company Oregon’s Wild Harvest, including precisely formulating the dosage and chemical composition of the Centella extract after first testing it in mouse models of Alzheimer’s Disease.

“The whole idea of the center is to build up the kind of preclinical information you need to do good clinical trials on botanicals that are used in dietary supplements,” said center director Amala Soumyanath, Ph.D., professor of neurology in the OHSU School of Medicine. “With Centella, we’re at that point.”

The study will test whether drinking the extract daily for six weeks changes biomarkers in the blood and brain associated with cognitive health. The study will include 48 participants, with half given the extract and half a placebo to drink daily over six weeks. Participants undergo blood draws and brain MRI scans as they start and finish the trial.

The investigators don’t expect that participants will improve their memory after only six weeks.

“The goal is to see whether this herb does something in the body that’s related to memory,” said clinical trial coordinator Alex Speers, N.D., assistant professor of neurology in the OHSU School of Medicine. “We’re not going to be able to show that it improves memory in this pilot study.”

If the pilot study discerns a statistically valid signal in the blood and brain scans, the next step would be to organize a much larger Phase 2 clinical trial, including hundreds of participants over months rather than weeks.

Ultimately, the research could lead to a botanical treatment for memory loss as well as more effective botanical supplements on the shelves.

“It might lead to manufacturers making better botanical products similar to this,” Soumyanath said. “Because we know precisely what’s in here, they might even be able to standardize production with the active compounds.”

This work was supported by an Alzheimer’s Association Grant (PTC REG-22-924617).