Reviewed: Downey LA, Kean J, Nemeh F, et al. An acute, double-blind, placebo-controlled crossover study of 320 mg and 640 mg doses of a special extract of Bacopa monnieri (CDRI 08) on sustained cognitive performance. Phytother Res. December 2012; [epub ahead of print]. doi: 10.1002/ptr.4864.
In Ayurvedic traditional medicine in India, Brahmi or bacopa (Bacopa monnieri, Scrophulariaceae) is a valued memory-enhancing, anti-amnesic, anxiolytic, sedative, and anti-epileptic treatment. Modern in vitro and in vivo studies have provided evidence suggesting several possible mechanisms for these effects. Over a dozen clinical trials have documented the positive effects of bacopa preparations (usually extracts) on learning, memory, information processing speed, and anxiety, as well as its antidepressant and cardiovascular effects. However, the majority of clinical trials have investigated the effects of chronic bacopa treatment; to date only one study has assessed its acute nootropic or cognitive-enhancing effects. The purpose of this double-blind, placebo-controlled, crossover clinical trial was to evaluate the effects of two dosage levels of special bacopa extract on mood, cardiovascular activity, and cognitive performance.
Healthy volunteers (n=24; aged 18-56 years, with a body mass index of 15.4-32.7 kg/m2) participated in this study conducted in Australia. Pre-screening exclusion criteria were as follows: smoking; any history of psychiatric disorders or neurological diseases; endocrine, gastrointestinal, or bleeding disorders; chronic illness and infection; pregnancy or lactation; and current use of medications or herbal supplements.
Subjects received a single acute dose of placebo (four 160 mg capsules of inert plant-based materials), 320 mg, and 640 mg of bacopa extract (KeenMind® [CDRI 08]; SFI Flordis; St. Leonards, NSW, Australia) in a three-arm crossover design. Each treatment was separated by a one-week washout period. The 50% ethanol bacopa extract was prepared from stems, leaves, and roots of a cultured variety of bacopa collected from West Bengal, India, and standardized to 55% total bacosides.
Each subject attended four assessment sessions — one practice visit and three study visits. On each study visit, tests were conducted prior to the acute dose (baseline) and then two hours after dosing. The tests included a cognitive demand battery (CDB) and assessments of blood pressure, arterial stiffness, and cerebral blood flow. The CDB was comprised of a subjective assessment of stress and mental fatigue on a visual analogue scale (VAS), serial threes and serial sevens subtraction tests (counting backward from a given number by threes or sevens), and the Bakan Rapid Visual Information Processing (BRVIP) task (identifying three consecutive series of odd or even numbers in a random series, evaluated for both accuracy and reaction time). Each CDB took 10 minutes and was conducted seven times per visit; one test before ingestion of the study medication and then six continuous tests starting two hours after ingestion.
Compared with placebo, 320 mg of this bacopa extract significantly improved performance of the serial threes subtraction test at the first (P=0.05) and fourth repetition (P=0.02). For all groups, there was a significant improvement over time on the serial threes test (P<0.001). There were no other significant findings for the serial threes test.
For the serial sevens subtraction test, the only significant change was an improved performance of the 640 mg dose of bacopa extract compared with the 320 mg dose at the first repetition (P<0.05). For all groups, there was a significant improvement over time on the serial sevens test (P<0.001).
There were no significant changes in the BRVIP task. The CDB significantly increased the subjective ratings of stress and fatigue (P<0.01); none of the treatments attenuated these effects. There were no significant changes in the cardiovascular assessments, and no adverse events occurred.
The authors hypothesize that greater cognitive enhancement could have occurred prior to the two-hour post-treatment assessment, which may explain why the improvements took place during the earliest repetitions. The authors conclude that the acute nootropic effect of this bacopa extract may be limited to early windows of activity (i.e., < two hours post-dosing).
It cannot be ruled out that any statistical significance may be due to chance, since there were six post-dosing tests conducted, and few showed any alterations. Another point to consider is that not all extracts are created equally, and other bacopa extracts may behave differently in this paradigm.
—Heather S. Oliff, PhD