Improving memory: Lion’s mane mushrooms may double neuron growth

Many claims are made about mushrooms’ medicinal properties due to the fact that fungi are capable of creating a vast array of molecules, not all of which have been studied for their individual properties or medicinal potential.

However, there is a lack of evidence to support these claims, largely as the molecules which could have a medicinal effect have not been isolated or studied in the laboratory or in humans. Many of the claims made also allude to the consumption of mushrooms as a whole rather than the effects of individual molecules they might contain, as the dietary supplement industry is not regulated in the same way that medicines are.

The fungi species, Hericium erinaceus, more commonly known as lion’s mane mushroom, has been used in traditional Chinese medicine for years and is the focus of many claims made about its potential medicinal uses.

Claims have been made about the potential benefits of this particular fungi in treating neurodegenerative conditions, and there is an ongoing trial to determine the effects of taking the fungi in capsule form on Parkinson’s disease patients, for example.

In order to observe the effect of the fungi on neurons in the laboratory, researchers in South Korea and Australia isolated several compounds from lion’s mane fungi as well as tested a crude extract from the mushrooms.

They published their findings in the Journal of Neurochemistry.

The study was funded by CNGBio Co, which farms organic mushrooms for medicinal purposes.

Lead author Professor Frédéric Meunier from the Queensland Brain Institute and former editor of the journal told Medical News Today why they decided to test this particular mushroom:

“I am a molecular neurobiologist, and we do grow neurons in a dish on an ongoing basis for many projects. One of my former Ph.D. student[s] YeJin Chai alerted me that the lion’s mane mushroom could have an activity on neurons and we, therefore, got involved in a collaboration and tested several compounds extracted from this mushroom.”

“It became clear that some of these compounds had potent activity when we realized that the length and number of branches dramatically increased,” he said.

To study this hypothesis, researchers exposed neurons derived from rat embryos to lion’s mane mushroom extracts for 24 hours and compared the length of the neurons and their branching to neurons in a control group.

They found the neurons exposed to lion’s mane mushroom extracts were up to twice as long as those not exposed.

Further analysis of cells from the hippocampus region of the brain showed that neurons showed the most growth when exposed to four separate isolated molecules with hericene A and NDPIH having the greatest effect on neuron growth.

Researchers then gave mice supplements of lion’s mane mushroom and tested their memory in a maze test.

They found that dietary supplementation with lion’s mane mushroom crude extracts significantly enhanced mice’s recognition memory.

Dr. Kelly Johnson-Arbor, medical toxicologist, co-medical director, and interim executive director at the National Capital Poison Center, who was not involved in the study, called the study an interesting piece of research that “will hopefully stimulate further research in this field.”

However, she also called for caution when interpreting the findings.

“For now, we don’t know whether the changes that were noted in the in vitro or mouse investigations are applicable to humans,” she stressed.

“If [lion’s mane] mushroom extract is found to be beneficial for human memory, additional studies will need to investigate the appropriate dose and length of treatment needed to result in beneficial clinical effects in humans.”— Dr. Kelly Johnson-Arbor

The safety profile of these molecules is also unclear for humans for now.

“Additionally, we don’t know if there are any side effects of this mushroom extract when used in humans. The study investigators did note that some chemicals that act on the brain extract can cause unwanted effects like pain, spasticity, and even brain damage, and we don’t know if lion’s mane mushroom extract will have similar adverse effects in humans,” Dr. Johnson-Arbor told MNT.

There is also the issue of supplement regulation.

“The dietary supplement industry is highly unregulated, and products marketed as dietary supplements are not FDA-approved to prevent, treat, or cure any disease. In addition, dietary supplements may contain unwanted contaminants or other ingredients that may be harmful when consumed by humans,” she said.

Dr. Meunier said that understanding the underlying mechanisms behind these findings is a priority for the team. This means that they will have to determine which receptors in the cell the different molecules are binding with and how.

“A clinical trial is ongoing in Korea to test the efficacy of some of these molecules in a cohort of Alzheimer patients,” he said.

“I am particularly interested in understanding how these molecules act on our nervous system. Finding the receptor will allow a much deeper understanding of how such receptor is involved in memory formation and how to generate optimized compounds that specifically target this receptor,” he concluded.