Washington, Dec 08 (ANI): A comprehensive review of research has failed to find convincing evidence of benefits related to popular herb ginseng which many people can improve thinking ability and prevent or even treat dementia.
"Ginseng appears to have some beneficial effects on cognition, behavior and quality of life," said JinSong Geng, lead review author.
"But at present, recommendations about [whether to take the herb] cannot be made due to the lack of high-quality evidence."
Ginseng - actually a number of closely related plant species - is among the most widely used herbs worldwide. It is said to provide a broad array of physical and mental benefits, including cognitive enhancement and protection against age-related decline and dementia.
The authors found five randomized, double blind, placebo-controlled studies that provided sufficient data for the researchers to analyze the herb's effectiveness. These studies comprised 289 patients, each of whom were healthy and without signs of dementia or cognitive decline.
Participants were predominantly young or middle-aged: their average age ranged from 20 to 31 in three of the studies, and in the 50s for the other two. Four studies analyzed the effects of ginseng over an eight-to-12 week period, while one looked at short-term effects after only two days of administration.
Individual studies showed superiority on some measures of cognitive function among participants taking ginseng. One study, which enrolled 16 individuals, found a statistically significant improvement in working memory. The same study associated ginseng with a significant increase in calmness.
Another trial, with 112 participants, found that the group receiving ginseng scored significantly better on some tests of learning and memory, but not on others.
Data on the effects of ginseng on reaction time were also inconsistent, and tests of attention and concentration were generally inconclusive.
Several studies showed improvements in some aspects of quality of life, including social relationships, general health and physical health among participants taking ginseng.
There were no serious side effects observed in connection with the herb.
One of the studies reported adverse effects like headache, dizziness, diarrhea and eczema, but these occurred in both ginseng and placebo groups, and were not severe.
Despite some positive findings, studies included in the systematic review did not add up to a "convincing" case for ginseng's effectiveness as a cognitive enhancer, the authors concluded.
In large part, this was because the authors could not combine data from the individual studies for a meta-analysis, due to differences among the studies in design, herbal preparations and tests used to measure cognitive function, Geng said.
The review has appeared in the latest issue of The Cochrane Library, a publication of the Cochrane Collaboration, an international organization that evaluates medical research. (ANI)