Is ginseng effective in improving cognitive function among older healthy participants, as compared to placebo?
Date of publication of the systematic review: December 2010
Design
Systematic review of randomized controlled trials (RCTs).
Participants
112 older healthy participants (mean age: 51.4 years in treatment group, 51. 5years in control group; male%: 34%). Participants with serious illness, dementia, mild cognitive impairment, diseases of the central nervous system, abuse of alcohol or drugs and those receiving psychoactive medication that might be interacting with ginseng were excluded.
Intervention
Ginseng extract was administrated orally with a dosage of 400 mg per day for an average duration of 8.5 weeks.
Comparator
Comparison: Ginseng extract (400mg/day) versus placebo with an identical appearance.
Major Outcomes
Outcome 1: Attention and concentration test score as measured at the end of treatment;
Outcome 2: Learning and memory test score as measured at the end of treatment;
Outcome 3: Sensorimotor function test score as measured at the end of treatment.
Settings
This study was performed in an outpatient setting.
Comparison    Ginseng extract (400mg/day) versus placebo
Main Results
Compared to the placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks did not show significant benefit on improving attention and concentration test score measured at the end of treatment (mean difference (MD): 4.00, 95% CI: -11.15 to 19.15) and sensorimotor function test score measured at the end of treatment (MD: -6.60, 95% CI: -15.72 to 2.52). However, compared to placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks showed significant improvement on learning and memory test score measured at the end of treatment (MD: 4.40, 95% CI: 0.82 to 7.98).
Comparison: Ginseng extract (400mg/day) versus placebo in cognitive function among healthy participants
Outcomes No. of studies (Total no. of participants) Mean score (SD)/ No. of participants Heterogeneity test (I2) MD (95% CI) Overall quality of evidence*
Intervention Comparator
1 1 (112) 41.5 (41.9)/55 37.5 (39.8)/57 Not applicable as there is only 1 study. 4.00 (-11.15 to 19.15) Low
2 1 (112) 1.3 (8.9)/55 -3.1 (10.4)/57 Not applicable as there is only 1 study. 4.40 (0.82 to 7.98) Moderate
3 1 (112) 0.8 (19.2)/55 7.4 (29.2)/57 Not applicable as there is only 1 study. -6.60 (-15.72 to 2.52 ) Low
Key: SD = standard deviation; MD = mean difference; CI = confidence interval.
Comparison    Ginseng extract (400mg/day) versus placebo
Main Results
Compared to the placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks did not show significant benefit on improving attention and concentration test score measured at the end of treatment (mean difference (MD): 4.00, 95% CI: -11.15 to 19.15) and sensorimotor function test score measured at the end of treatment (MD: -6.60, 95% CI: -15.72 to 2.52). However, compared to placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks showed significant improvement on learning and memory test score measured at the end of treatment (MD: 4.40, 95% CI: 0.82 to 7.98).
Comparison: Ginseng extract (400mg/day) versus placebo in cognitive function among healthy participants
Outcomes 1 2 3
No. of studies (Total no. of participants) 1 (112) 1 (112) 1 (112)
Mean score (SD)/ No. of participants Intervention 41.5 (41.9)/55 1.3 (8.9)/55 0.8 (19.2)/55
Comparator 37.5 (39.8)/57 -3.1 (10.4)/57 7.4 (29.2)/57
MD (95% CI) 4.00 (-11.15 to 19.15) 4.40 (0.82 to 7.98) -6.60 (-15.72 to 2.52 )
Overall quality of evidence* Low Moderate Low
Key: SD = standard deviation; MD = mean difference; CI = confidence interval.
Conclusion
Benefits
Compared to placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks did not show significant improvement on attention and concentration test score and sensorimotor function test score measured at the end of the treatment in healthy participants. However, compared to placebo, ginseng extract (400mg/day) for an average duration of 8.5 weeks showed significant improvement on learning and memory test score measured at the end of the treatment. For outcomes 1 and 3, the overall quality of evidence is low. Further research is likely to have an important impact on our confidence in this estimate of effect. For outcome 2, the overall quality of evidence is moderate. Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
Harms
No adverse events were reported in the trial.
Link to Original Article
http://www.ncbi.nlm.nih.gov/pubmed/21154383
The synopsis is based on the following article:
Geng J, Dong J, Ni H, Lee MS, Wu T, Jiang K, et al. Ginseng for cognition. Cochrane Database Syst Rev. 2010 Dec 8;(12):CD007769.


* Interpretation of quality assessment results:
• Very low: Further research is most likely to have an important impact on our confidence in this estimate of effect.
• Low: Further research is likely to have an important impact on our confidence in this estimate of effect.
• Moderate: Further research is fairly likely to have an important impact on our confidence in this estimate of effect.
• High: Further research is unlikely to have an important impact on our confidence in this estimate of effect.
• Very high: Further research is most unlikely to have an important impact on our confidence in this estimate of effect.

Details of assessment method can be found at Chung VC, Wu XY, Ziea ET, Ng BF, Wong SY, Wu JC. Assessing internal validity of clinical evidence on effectiveness of CHinese and integrative medicine: Proposed framework for a CHinese and Integrative Medicine Evidence RAting System (CHIMERAS). European Journal of Integrative Medicine. 2015 Aug 31;7(4):332-41.