The Cognitive-Enhancing Effects of Bacopa monnieri: A Systematic Review of Randomized, Controlled Human Clinical Trials

Objectives: Traditional knowledge suggests that Bacopa monnieri enhances cognitive performance. Such traditional beliefs have now been scientifically tested through a handful of randomized, controlled human clinical trials. The current systematic review aimed to examine the scientific evidence as to whether Bacopa can enhance cognitive performance in humans. Design: A systematic review of randomized controlled trials is presented. Multiple databases were systematically searched by multiple authors. Relevant trials were objectively assessed for methodological quality. Subjects: The subjects studied were adult humans without dementia or significant cognitive impairment. Interventions: B. monnieri, including Bacopa extracts, were administered over long-term supplementation periods. Outcome measures: Any validated cognitive test, whether a primary or secondary outcome. Results: Six (6) studies met the final inclusion criteria and were included in review. Trials were all conducted over 12 weeks. Across trials, three different Bacopa extracts were used at dosages of 300-450 mg extract per day. All reviewed trials examined the effects of Bacopa on memory, while other cognitive domains were less well studied. There were no cognitive tests in the areas of auditory perceptual abilities or idea production and only a paucity of research in the domains of reasoning, number facility, and language behavior. Across studies, Bacopa improved performance on 9 of 17 tests in the domain of memory free recall. There was little evidence of enhancement in any other cognitive domains. Conclusions: There is some evidence to suggest that Bacopa improves memory free recall with evidence for enhancement in other cognitive abilities currently lacking perhaps due to inconsistent measures employed by studies across these cognitive domains. Research into the nootropic effects of Bacopa is in its infancy, with research still yet to investigate the effects of Bacopa across all human cognitive abilities. Similarly, future research should examine the nootropic effects of Bacopa at varied dosages and across different extracts.