Medicinal Plants and the Brain – Ginkgo, Lemon Balm, and Rhodiola

This is the second article in the series on the influence of medicinal plants on the brain. I am describing plants where we have at least one positive double-blind, placebo-controlled trial in humans that supports their medicinal use in brain-related disorders. The last article described St. John’s wort, ashwagandha, and American skullcap, and we can certainly see there is a promising trend towards scientific support for the use of these ancient medicinal herbs.


Ginkgo is a slow growing deciduous tree that grows up to 125-foot-tall and can survive for up to 1000 years. Ginkgo is the oldest surviving tree on Earth as the species dates back to the Jurassic era some 200 million years ago. It has changed remarkably little morphologically since then. It also happens to be one of the best researched medicinal plants with several high-profile publications. A study published in JAMA in 1997 concluded that treatment with ginkgo leaf extract of patients with dementia was safe and capable of improving or stabilizing cognitive performance and social functioning. Another well-controlled study published in 2006 confirmed this result as gingko was found comparable to donepezil in clinical efficacy for dementia treatment. However, a later JAMA study released in 2008 demonstrated ginkgo does not act to prevent dementia occurring in the first place. Ginkgo has also been found effective in the treatment of anxiety, although it is better known as a circulatory stimulant and nootropic (cognitive enhancer). Ginkgo, like the widely used anti-depressant and nervine tonic St. John’s wort, is an example of a medicinal plant success story.

Lemon balm

Lemon balm is another medicinal plant with an ancient history of use by the Romans, ancient Greeks, and Arabs for its medicinal properties. The 11th century Arab physician, Avicenna, wrote, ‘Balm causeth the mind and heart to become merry’. In the middle ages, Europeans used the herb to reduce anxiety and it also became known as something of a cure-all. It is unclear how well founded their belief in lemon balm was as in modern times it is mainly known as an anxiolytic (reduces anxiety), nootropic, anti-depressant, and carminative (reduces excess gas). Double-blind placebo-controlled human studies have shown positive results for lemon balm extracts in the improvement of mood, reduction of anxiety, and improvement of cognitive abilities. These preliminary human trials suggest much of its more recent traditional use is justified.


Rhodiola rosea may have been used as long ago as the Vikings to reduce fatigue and enhance the capacity to work. In an old Icelandic text from 1783, it is described as a herb to enhance the intellect and restore weak nerves. For many centuries Rhodiola was used by folk herbalists in Russia and Scandinavia as a whole-body tonic. There is strong scientific support for the reduction of fatigue with positive results in three well-controlled clinical trials. There is an additional study that found an improvement in mood in the treatment of mild to moderate depression.

Rhodiola is viewed as an adaptogen by modern herbalists, having the dual properties of relaxing and stimulating the nervous system to some degree. Adaptogens can be further grouped depending on how stimulating they are, Rhodiola is more on the stimulating side so should be taken in the morning to avoid insomnia. Ashwagandha, as described in the previous article, is a more calming adaptogen with a greater capacity to support sleep.

Alexander Panossian, the world’s foremost scientific authority on adaptogens, has published a recent review in 2017 describing the mechanism by which adaptogens are thought to work. Our current understanding is they prime the stress response system, namely the sympatho-adrenal or hypothalamic-pituitary-adrenal axes of the endocrine system, in a gentle manner that prepares the body for future stressors or adapting to chronic ones (e.g., major depression). It is thought that the modulation of stress hormones like cortisol and heat shock proteins like HSP70 is central to this mechanism.

A final cautionary note is that adaptogens should not replace good sleep and lifestyle habits. Although they are very mild relative to illegal alternatives, using them inappropriately as stimulants to replace poor sleep habits, in a similar manner to coffee, can eventually lead to burnout. It will be interesting to see how many additional traditional medicinal properties of the adaptogens will be confirmed by modern medical science.


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Image via kerdkanno/Pixabay.


I have a Bsc in Biochemistry and Msc in Regenerative Medicine from Sheffield, U.K., and PhD in Plant Science and Bioinformatics from Cambridge, U.K. I have an ongoing interest in the medicinal properties of plants and exploring both scientific and traditional knowledge, I run a non-profit website related this subject (
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