Efficacy of Bacopa Monnieri (Brahmi) and Donepezil in Alzheimer's Disease and Mild Cognitive Impairment: A Randomized Double-Blind Parallel Phase 2b Study.

The short version

This trial put Bacopa monnieri (Brahmi), a traditional Ayurvedic memory herb, head-to-head against donepezil, the standard prescription drug for Alzheimer's disease, in people already diagnosed with Alzheimer's or the earlier-stage memory decline called mild cognitive impairment. The goal was to see whether a natural alternative could match the drug doctors currently rely on, since no treatment yet slows the underlying disease. The trial planned to enroll 48 adults over age 50 with brain-imaging-confirmed diagnoses, giving half 300 mg of Bacopa daily and half 10 mg of donepezil daily for a full year, then comparing memory and thinking-skills tests (governing recall, word-finding, and daily-living ability) at regular checkpoints. Because recruitment was slower than expected, the study ran for nearly four years but still only enrolled 34 of the planned 48 participants before it had to close early. On the main measure of cognitive decline (ADAS-Cog, a standard Alzheimer's test), Bacopa and donepezil performed statistically the same at every checkpoint through one year. A second memory test (the PGI Memory Scale) also showed no difference at 3, 6, or 9 months, though the total score did differ significantly between groups at the final 12-month assessment, favoring donepezil, while the individual parts of that same test showed no difference. Because the trial closed early with roughly a third fewer participants than planned, its ability to detect a real difference between the two treatments was limited, and the one late significant result should be read cautiously alongside the many outcomes that showed no difference. The findings suggest Bacopa performs comparably to donepezil on most measures over one year, but the authors themselves call for larger, multi-site trials before drawing firmer conclusions about how the two options truly compare.

Key findings

• In a phase 2b trial of 34 patients (a third fewer than the planned 48, due to early termination from slow recruitment), Bacopa monnieri 300mg daily showed no significant difference from donepezil 10mg daily on the ADAS-Cog cognitive test at any time point over one year.
• The PGI Memory Scale also showed no difference between Bacopa and donepezil at 3, 6, or 9 months, though a statistically significant difference in the total score emerged at the final 12-month assessment, favoring donepezil.
• That late difference in total PGI Memory Scale score was not reflected in the scale's individual sub-scores, making it an isolated finding rather than a consistent pattern across the trial's outcome measures.
• The trial's early termination substantially reduced its statistical power to detect true differences between Bacopa and donepezil, and the authors call this a key limitation of their findings.
• The study authors recommend larger, multicenter phase 3 trials before drawing firm conclusions about whether Bacopa monnieri is comparable, inferior, or superior to donepezil for Alzheimer's disease and mild cognitive impairment.

Common questions