Gotu Kola for Cognition, Anxiety and the Brahmi Confusion

Gotu kola is sold worldwide as a memory herb. The strongest scientific support for that claim belongs to a different plant.

Both Centella asiatica and Bacopa monnieri are called brahmi. They are unrelated species in different botanical families with different active compounds and different clinical evidence. Bacopa has been through nine randomised placebo-controlled trials pooled in a meta-analysis, and it moved cognitive measures. Gotu kola has been through a meta-analysis too — and it found no significant effect in any cognitive domain.

Sorting that out is the main job of this article, because the two plants’ reputations have been merged in the marketplace, and the merger runs in one direction: Bacopa’s data props up Centella’s marketing. Gotu kola does have a real, if small, signal of its own — on alertness, anger and acute stress reactivity, not on memory. That signal is worth knowing about, and it is worth not overstating.

Table of Contents

1. Two Plants, One Name
2. Why the Confusion Is Not Harmless
3. Different Families, Different Chemistry
4. What Bacopa’s Evidence Actually Shows
5. The Gotu Kola Meta-Analysis
6. The Elderly-Volunteer Study
7. The Post-Stroke Study
8. Anxiety and the Startle Reflex
9. The Animal Work, and Why It Is Not Enough
10. How to Tell Which Plant You Have
11. The Verdict
12. Cautions
13. Key Research Papers
14. Connections

Two Plants, One Name

Brahmi derives from Brahma, the creator in Hindu cosmology, and in Ayurvedic usage denotes a herb that supports intellect and consciousness — a medhya rasayana, a mind-rejuvenating remedy. The name has been attached to at least two plants for centuries.

Many Ayurvedic scholars argue the two names were originally distinct: brahmi for Bacopa, mandukaparni (“frog-leaf”, for the leaf shape) for Centella, with the conflation a later regional drift — brahmi tending to mean Bacopa in the north and east and Centella in parts of the south and in Sri Lanka. Whatever the history, the practical situation today is that a jar labelled “Brahmi” may contain either plant, and the label may not say which.

Why the Confusion Is Not Harmless

A shared common name would be a curiosity if the two plants had similar evidence. They do not, and the asymmetry matters in four concrete ways.

1. You may buy the wrong plant for your goal. If you want the memory herb with trial support, you want Bacopa. If you buy gotu kola because the bottle says brahmi, you have bought a vein and skin herb.
2. The safety profiles differ. Bacopa’s characteristic side effects are gastrointestinal — nausea, cramping, loose stools — and it should be taken with food. Gotu kola’s documented problems are allergic contact dermatitis with topical use and rare liver injury with prolonged oral use. Swapping one for the other swaps the risks you should be watching for.
3. Citations get laundered. Search any supplement retailer and you will find gotu kola pages citing memory studies that were run on Bacopa. Once a claim is transferred it propagates, and eventually it reaches articles, then physicians, then patients.
4. It corrupts the research record. Reviewers of the Ayurvedic literature repeatedly have to disentangle which plant a historical study actually used, because older papers sometimes name only “brahmi”.

Different Families, Different Chemistry

Both plants make triterpenoid saponins, which is probably why the traditions grouped them — both taste bitter and both are creeping marsh plants. Chemically that resemblance is superficial.

Gotu kola’s asiaticoside and madecassoside are pentacyclic triterpenes of the ursane type: five fused rings. Their best-documented biological activity is on fibroblasts, collagen synthesis and vascular endothelium — connective tissue chemistry, which is exactly why the plant works where it works.

Bacopa’s bacosides are dammarane-type triterpenoid saponins — a tetracyclic skeleton closer to the ginsenosides of ginseng than to anything in Centella. Their proposed activity concerns cholinergic transmission, dendritic branching in the hippocampus and antioxidant effects in nervous tissue.

Two plants can both contain “triterpene saponins” and share as little pharmacology as aspirin and morphine share by both being small organic molecules. The category is too coarse to transfer a claim across.

What Bacopa’s Evidence Actually Shows

To make the comparison fair, here is the other plant’s evidence, reported at the same standard as gotu kola’s.

Kongkeaw and colleagues (2014) searched ten databases for randomised, placebo-controlled trials of standardised Bacopa extract dosed for at least twelve weeks without co-medication. Nine studies with 518 subjects met criteria; 437 subjects entered the meta-analysis. Results: a shortened Trail Making Test B time (−17.9 ms, 95% CI −24.6 to −11.2, p < 0.001) and faster choice reaction time (95% CI −12.1 to −9.2, p < 0.001). The authors described the overall risk of bias as low. Their conclusion was measured: Bacopa has potential to improve cognition, particularly speed of attention, but only a large head-to-head trial against an existing medication would be definitive.

Pase and colleagues (2012) reviewed six randomised controlled trials, all twelve weeks long, using three different extracts at 300–450 mg/day. Bacopa improved performance on 9 of 17 tests of memory free recall, with little evidence of benefit in other cognitive domains. Stough and colleagues (2001) is the individual trial most often cited, reporting improved delayed word recall after twelve weeks in healthy adults.

Read that honestly and it is not a miracle either. The effects are on the order of milliseconds of reaction time and a few extra recalled words, in healthy adults, after three months. But it is a coherent, replicated, meta-analysable body of work in the specific domain of memory. Gotu kola has no equivalent.

The Gotu Kola Meta-Analysis

Puttarak and colleagues published the definitive assessment in Scientific Reports in 2017. They gathered five randomised controlled trials of Centella asiatica alone and six of Centella-containing products.

The central finding, stated plainly in the paper: “there are no significant differences in all cognitive function domains of C. asiatica when compared to placebo.”

Not a small effect. Not an effect limited to one subgroup. No significant difference in any cognitive domain measured.

What the meta-analysis did find, and this is the part usually ignored in both directions:

• Improved alertness — standardised mean difference 0.71 (95% CI 0.01 to 1.41).
• Reduced anger at one hour after treatment — SMD −0.81 (95% CI −1.51 to −0.09).
• No adverse effects reported in any of the included studies.

Look closely at those confidence intervals. Both barely exclude zero — the alertness interval runs from 0.01, which is as close to nothing as an interval can get and still be called significant. These are fragile findings on mood-scale outcomes measured an hour after a dose, not durable cognitive enhancement.

The authors closed by noting limitations in dose regimen, plant preparation, standardisation and product variation, and calling for well-designed trials using standardised extract. That is a reasonable position: the question has not been asked well enough to be closed. But as it stands, the memory claim on a gotu kola label is not supported by the meta-analysis of gotu kola trials.

The Elderly-Volunteer Study

The single study most cited in support of gotu kola for cognition is Wattanathorn and colleagues, 2008, from Khon Kaen University in Thailand. It is randomised, placebo-controlled and double-blind — good design — and it enrolled 28 healthy elderly participants across doses of 250, 500 and 750 mg once daily for two months, plus placebo.

Twenty-eight people spread over three active doses and a control arm is roughly seven people per group. That is a pilot, and no conclusion of any strength can rest on it.

What it reported: the high dose (750 mg) enhanced working memory and increased the N100 amplitude of the event-related potential — an electrophysiological marker of early attention. Self-rated mood improved on the Bond–Lader scales.

Two observations. First, the benefit appeared at the top dose only, which is a dose–response pattern and mildly reassuring, but with seven per arm it could equally be noise. Second, notice what the positive results actually were: working memory and an attention marker and mood. That is the same alertness-and-mood cluster the meta-analysis later isolated. The study is more consistent with “this herb makes people feel more alert” than with “this herb improves memory”.

The Post-Stroke Study

Farhana and colleagues, working in Yogyakarta, Indonesia, studied gotu kola in 48 patients with vascular cognitive impairment after stroke: 17 received 1000 mg/day of gotu kola extract, 17 received 750 mg/day, and 14 received folic acid 3 mg/day, for six weeks, with the Indonesian Montreal Cognitive Assessment (MoCA-Ina) before and after.

The result: all three groups improved, with no significant difference between them. The authors read that as gotu kola being as effective as folic acid, and reported that gotu kola did better in the memory domain specifically.

There are three reasons to hold that lightly. It was a quasi-experimental design, not a randomised controlled trial — the paper says so. There was no placebo arm: folic acid is not an established treatment for post-stroke cognitive impairment, so “as good as folic acid” may mean “as good as nothing”. And people recovering from stroke improve on their own, while repeating a cognitive test after six weeks produces a practice effect. Three groups all improving is exactly what you would expect if none of the treatments did anything.

It is not a bad study for its setting, and the finding is worth following up. It is not evidence that gotu kola treats post-stroke cognitive impairment.

Anxiety and the Startle Reflex

Here gotu kola has its most interesting result, and it is not a cognitive one.

Bradwejn and colleagues at the University of Ottawa ran a double-blind, placebo-controlled study of the acoustic startle response — the involuntary jump to a sudden loud noise, an objective and hard-to-fake measure of how reactive your threat system is. Forty healthy subjects were randomised, 20 to a single oral dose of gotu kola and 20 to placebo.

Compared with placebo, gotu kola significantly reduced peak startle amplitude at 30 and 60 minutes. It had no effect on self-rated mood, heart rate or blood pressure.

That combination is unusual and worth dwelling on: an objective physiological measure of anxiety reactivity moved, while the subjective one did not. It is harder to explain by expectation than a questionnaire result would be.

Now the catch. The dose was 12 grams of gotu kola, taken at once. A typical commercial capsule contains 450–500 mg of dried herb; the standardised extracts used in the venous trials deliver 60–180 mg of triterpenes per day. Twelve grams is roughly twenty-five capsules in a single sitting. Whatever this study demonstrates about the plant’s pharmacology, it says almost nothing about what two capsules a day will do.

The other anxiety study, Jana and colleagues in Kolkata, gave 500 mg of a hydro-ethanolic extract twice daily for 60 days to 33 people with generalised anxiety disorder and reported significant reductions in anxiety, stress and depression scores. It was uncontrolled — no placebo group, no blinding, no randomisation. In anxiety, where placebo response rates in controlled trials routinely reach 30–40%, an uncontrolled study cannot distinguish drug effect from expectation, regression to the mean and the attention of being in a study.

The Animal Work, and Why It Is Not Enough

The laboratory case for gotu kola in the brain is genuinely substantial. Gray and colleagues at Oregon Health and Science University gave a water extract of Centella asiatica to twenty-month-old mice in their drinking water for two weeks and found improvement across novel object recognition, object location memory and odour discrimination reversal learning — hippocampal, cortical and prefrontal tasks respectively. Golgi analysis showed increased dendritic spine density, alongside raised expression of the antioxidant regulator NRF2 and the mitochondrial marker porin. Their broader review sets out the neuroprotective and cognitive mechanisms in detail.

This is careful, mechanistically specific work, and it is the reason serious researchers keep studying the plant. It is also mouse work. The history of cognitive pharmacology is a graveyard of compounds that increased synaptic density in aged rodents and did nothing measurable in people. The human trials are the test, and the human trials are the ones that came back null.

How to Tell Which Plant You Have

1. Find the Latin binomial. Centella asiatica or Bacopa monnieri. If a product says only “Brahmi”, you cannot know what is in it, and that alone is a reason to choose a different brand.
2. Check the standardisation marker. Bacopa products state a bacoside percentage, typically 20–55%. Gotu kola products state triterpenes, asiaticoside, or “titrated extract”. The marker names the plant.
3. Check the dose against the literature. Bacopa cognitive trials used 300–450 mg of extract daily for at least twelve weeks. Gotu kola trials used 60–180 mg of triterpenic fraction, or 250–750 mg of a cruder extract.
4. Be suspicious of “brahmi complex” blends. Products containing both plants plus ashwagandha, shankhpushpi and others make it impossible to attribute anything, and often supply sub-trial doses of each.
5. Match the plant to the goal. Memory and attention: Bacopa. Skin, scars, veins: gotu kola. Alertness and irritability: gotu kola has a weak signal. Neither is a treatment for a diagnosed anxiety disorder, depression or dementia.

The Verdict

If you have tried gotu kola and felt calmer or sharper, that experience is not being dismissed. Feeling more alert is precisely what the meta-analysis picked up, and the startle-response work suggests a real physiological effect on arousal. What the evidence does not support is the durable memory enhancement the packaging promises — and if that is what you are after, the honest answer is that you have the wrong brahmi.

Cautions

• Cognitive decline needs assessment, not a supplement. New memory problems can come from thyroid disease, B12 deficiency, depression, sleep apnoea, medication side effects and many treatable causes. Get them looked for before self-treating.
• Anxiety disorders have treatments that work. Cognitive behavioural therapy and established medications have far better evidence than either brahmi. A herb is not a reason to postpone care.
• Sedation stacks. Gotu kola may add to the effects of alcohol, benzodiazepines, sleep medication and anaesthesia. Stop it about two weeks before planned surgery.
• Liver. Rare hepatotoxicity has been reported with oral use over 20–60 days. Use time-limited courses, avoid with liver disease, and stop for unexplained fatigue, nausea, dark urine or jaundice.
• Pregnancy and breastfeeding. Avoid oral gotu kola. Bacopa is likewise not established as safe in pregnancy.
• The 12 g dose is not a recommendation. It was a one-off experimental dose in a supervised study. Do not reproduce it.

Key Research Papers

Centella asiatica

1. Puttarak P, Dilokthornsakul P, Saokaew S, Dhippayom T, Kongkaew C, Sruamsiri R, et al. Effects of Centella asiatica (L.) Urb. on cognitive function and mood related outcomes: a systematic review and meta-analysis. Scientific Reports. 2017;7(1):10646. Five RCTs of Centella alone; no significant difference in any cognitive domain versus placebo; improved alertness and reduced anger.
2. Wattanathorn J, Mator L, Muchimapura S, Tongun T, Pasuriwong O, Piyawatkul N, et al. Positive modulation of cognition and mood in the healthy elderly volunteer following the administration of Centella asiatica. Journal of Ethnopharmacology. 2008;116(2):325–332. 28 volunteers across 250/500/750 mg and placebo; benefit at the high dose only.
3. Bradwejn J, Zhou Y, Koszycki D, Shlik J. A double-blind, placebo-controlled study on the effects of gotu kola (Centella asiatica) on acoustic startle response in healthy subjects. Journal of Clinical Psychopharmacology. 2000;20(6):680–684. 40 subjects; single 12 g dose; startle amplitude reduced at 30 and 60 minutes.
4. Jana U, Sur TK, Maity LN, Debnath PK, Bhattacharyya D. A clinical study on the management of generalized anxiety disorder with Centella asiatica. Nepal Medical College Journal. 2010;12(1):8–11. 33 participants, uncontrolled and unblinded.
5. Farhana KM, Malueka RG, Wibowo S, Gofir A. Effectiveness of gotu kola extract 750 mg and 1000 mg compared with folic acid 3 mg in improving vascular cognitive impairment after stroke. Evidence-Based Complementary and Alternative Medicine. 2016;2016:2795915. 48 patients, quasi-experimental, no placebo arm.
6. Gray NE, Zweig JA, Caruso M, Martin MD, Zhu JY, Quinn JF, et al. Centella asiatica increases hippocampal synaptic density and improves memory and executive function in aged mice. Brain and Behavior. 2018;8(7):e01024. Twenty-month-old mice; increased spine density, NRF2 and porin.
7. Gray NE, Alcazar Magana A, Lak P, Wright KM, Quinn J, Stevens JF, et al. Centella asiatica: phytochemistry and mechanisms of neuroprotection and cognitive enhancement. Phytochemistry Reviews. 2018;17(1):161–194. The detailed mechanistic review.

Bacopa monnieri — the other brahmi

1. Kongkeaw C, Dilokthornsakul P, Thanarangsarit P, Limpeanchob N, Norman Scholfield C. Meta-analysis of randomized controlled trials on cognitive effects of Bacopa monnieri extract. Journal of Ethnopharmacology. 2014;151(1):528–535. Nine trials, 518 subjects; improved Trail B time and choice reaction time.
2. Pase MP, Kean J, Sarris J, Neale C, Scholey AB, Stough C. The cognitive-enhancing effects of Bacopa monnieri: a systematic review of randomized, controlled human clinical trials. Journal of Alternative and Complementary Medicine. 2012;18(7):647–652. Six trials at 300–450 mg/day; improvement on 9 of 17 memory free-recall tests.
3. Stough C, Lloyd J, Clarke J, Downey LA, Hutchison CW, Rodgers T, et al. The chronic effects of an extract of Bacopa monniera (Brahmi) on cognitive function in healthy human subjects. Psychopharmacology. 2001;156(4):481–484. The individual trial most often cited for delayed word recall.

Live PubMed Searches

1. Centella asiatica and cognitive function — randomised trials
2. Bacopa monnieri and memory — randomised trials
3. Brahmi and the medhya rasayana herbs in Ayurveda
4. Centella asiatica and anxiety — clinical studies
5. Acoustic startle response as an anxiolytic measure
6. Species substitution in herbal supplements — DNA barcoding studies

Connections

• All Herbs
• Gotu Kola Benefits (hub)
• Gotu Kola (main page)
• Bacopa Monnieri — the other “brahmi”
• Forms, TECA and Topical Use
• Wound Healing and Scars
• Venous Insufficiency and Circulation
• Calendula
• Dermatology

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