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- Bacopa (Bacopa monnieri)
- Cognition
- Memory
| Date:
08-31-2012 | HC# 081261-455
|
Re: Systematic Review Suggests Bacopa Extracts Improve Free Recall Memory
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. J Altern Complement Med. 2012;18(7):647-652.
Bacopa
(Bacopa monnieri) has been used in Ayurveda
since the 6th century for treating various mental conditions and as
a potent memory enhancer. Similarly, it is currently used for cognitive
enhancement. Bacopa's mechanisms of action include antioxidant activity, beta-amyloid
scavenging, neuroprotection, modulation of acetylcholine levels, and modulation
of cholinergic neuron density. According to the authors, this is the first
report to systematically review the cognitive-enhancing benefits of bacopa in
humans.
The
following databases were searched through April 2011: Scopus, PubMed, and the
Cochrane Library. The following key words and truncations were used: cognit or
memory or neuropsycholog or neurocognit or executive function with bacopa or
brahmi or bacoside or water hyssop. Included studies were randomized,
controlled trials conducted in adult humans with no cognitive impairment;
bacopa was a monotherapy; methodologic quality was ≥ 5 on the modified Jadad
scale; efficacy was based on valid tests of cognitive outcomes; and bacopa
treatment lasted for ≥ 4 weeks. All languages were included.
Each
trial was analyzed for methodologic quality using a purpose-designed modified
Jadad scale. The original Jadad scale is out of 5 points. This modified version
is out of 10 points. For the modified score, 1 point was given when each of the
following criteria was satisfied, with higher scores reflecting superior
methodologic quality: (1) Was the study randomized? (2) Was randomization
detailed and appropriate? (3) Was the study double-blind? (4) Was the blinding
detailed and appropriate? (5) Was there a control group? (6) Was the control described
in detail and appropriate? (7) Were the exclusion criteria adequate? (8) Was
the dosage used a therapeutic amount? (9) Were withdrawals and dropouts
described? and (10) Were the data reported clearly and adequately? The data gathered
from each study included general study descriptives as well as all cognitive
outcomes and their reported significance. Only results from the longest time
points for each study were included. Cognitive outcomes from each study were
grouped into the true cognitive abilities by 2 neuroscientists.
A
total of 64 studies were located; only 6 met all inclusion criteria. All of the
studies were randomized, double-blind, placebo-controlled, parallel-group
studies with a 12-week duration. Study populations were described as comparable
in age range, and all subjects were healthy. One study recruited a sample with subjective
memory complaints, but the patients did not have cognitive impairment. The
average quality of trials was high, with a modified Jadad mean score of 8.5. Three
studies evaluated KeenMind® (Flordis; Crows Nest, New South Wales,
Australia), 2 evaluated BacoMind® (Natural Remedies Pvt. Ltd.; Bangalore,
India), and 1 evaluated Mediherb® Bacopa (Mediherb; Warwick,
Queensland, Australia). Dosages of these dry extracts (herb to extract ratio of
20:1, except Mediherb Bacopa, 50:1) ranged from 300 to 450 mg/day. All 3
products use different extraction solvents and methods, different plant parts,
and different dosage equivalents to dried herbs. None of the studies included cognitive
tests for abilities in auditory perception or in producing and retrieving ideas,
words, and figural creations.
Two
studies evaluated reasoning abilities, and bacopa was not effective in this
domain. One study evaluated language behavior and number facility, and bacopa
was not effective in this domain. Five studies used 9 cognitive tests of visual
perceptual abilities, and in 1 study bacopa was effective for reduced reaction
time, while in 1 other study bacopa was effective for rapid visual information processing
tasks. Three studies evaluated mental speed, and bacopa was only effective for
inspection time. All of the studies evaluated memory; the majority of tests were
in the domain of free recall memory (auditory verbal learning test was used
most frequently). Across all of the studies, bacopa improved free recall memory
in 9 of 17 tests in this domain.
The
authors conclude that some evidence suggests that bacopa is efficacious in
improving free recall of information in subjects without memory impairment. The
authors believe that bacopa could potentially be prescribed as a memory
enhancer. However, longer-term studies are needed with manipulation of dosage
sizes, as well as studies that evaluate reasoning, mental speed, idea production,
language behavior, and number facility.
It
is particularly impressive that the included studies had such a high modified
Jadad score. It would be of value to see how the studies would score on the
regular Jadad score, which is used more frequently in systematic reviews. It is
interesting that the products tested were relatively different, and yet they
still benefited the same clinical domain.
—Heather S. Oliff,
PhD
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