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Mild cognitive impairment (MCI) is a condition that may be prodromal to the development of dementia. There remain, as yet, no approved pharmaceutical interventions for MCI. Chinese herbal medicines (CHMs) have a long history of use for cognitive impairments and some plant ingredients have shown neuroprotective actions in experimental studies. This review assesses the current clinical evidence from controlled clinical trials for the effects of CHMs on cognitive outcomes as measured by Mini-mental state examination (MMSE) or Alzheimer's Disease Assessment Scale-Cognitive subscale (ADAS-Cog). Fifty one studies (4026 participants) were included. These compared CHM with placebo, supportive care, pharmaceutical treatment or combined CHM with a pharmaceutical in an integrative setting. For the eight randomised controlled trials (RCTs) of comparisons with placebo, MMSE was significantly higher in the CHM groups (MD 1.56 [0.78, 2.34] I = 85%, n = 503), similarly for eight RCTs of comparisons with supportive care (MD 1.77 [1.33, 2.21] I = 0%, n = 555). Benefits were also evident in comparisons with some pharmaceuticals and with integrative treatment. The small size of most studies and methodological weaknesses mean that these results should be interpreted with caution. Further studies employing rigorous methods are required to investigate the potential benefits of these CHMs for MCI. Copyright © 2016 John Wiley & Sons, Ltd.

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Management of the behavioural and psychological symptoms of dementia remains a challenge worldwide. Herbal medicines may play a role in the development of new interventions. To determine effects of herbal medicines for management of the behavioural and psychological symptoms of dementia, meta-analysis was conducted of 31 controlled trials (3613 participants). Frequently tested herbal medicines were the Ginkgo biloba leaf extract EGb 761 (seven studies) and the multi-ingredient formula Yokukansan (eight studies). Sixteen studies tested other herbal medicines. Improvements were detected in Neuropsychiatric Inventory scores in EGb 761 groups compared to placebo (MD -3.46 [-5.94, -0.98]; I = 93%; n = 1757) and Yokukansan groups compared to no treatment (SMD -0.53 [-0.86, -0.21]; I = 0%; n = 150). Cognitive scores were improved in EGb 761 groups while Yokukansan did not appear to affect cognitive function. Of the other herbal medicines, there were improvements in the behavioural and psychological symptoms of dementia and cognitive outcomes in two of four placebo-controlled studies. EGb 761 and Yokukansan appeared safe and well tolerated. Adverse effects and dropouts were not reported consistently for the other herbal medicines. Weaknesses of these included short durations, small sample sizes, lack of blinding and other risks of bias. Well-designed studies are needed to further investigate the reported effects of these interventions on the behavioural and psychological symptoms of dementia.

The results suggested that the clinical benefits of the TMs were not less than donepezil at comparable time points, with both groups showing improvements. However, lack of blinding in most studies and other design and measurement issues are likely to have resulted in overestimation of effect sizes in both groups. Further well-designed studies are needed.