Can Marijuana Regenerate Brain Nerve Endings? Fact or Fiction
Many advocates of full marijuana legalization often claim that cannabinoids found in the plant have healing effects on brain neurons—not only protecting them from stress and death but also restoring their functionality. Unfortunately, a recently published study presents arguments that refute these properties.
According to scientists from California State University, the hippocampus in the human brain is physiologically incapable of supporting the regeneration of nerve connections in adults. In other words, their work contradicts over 20 years of research suggesting that this brain region can regenerate lost nerve endings. While studies on animals like rats and mice show that some living creatures’ brains retain the ability to reproduce nerve cells, this ability has not been observed in the human hippocampus.
“Of course, statements like ‘physical exercise stimulates nerve cell regeneration in mice’ or ‘CBD protects rat nerves from dying’ sound impressive, but the processes observed in rodents are not typical for the human body,” says neurologist Dr. Michele Ross. “Both human experiments and direct brain tissue analysis show that cannabinoids do not stimulate neurogenesis. While some compounds have strong neuroprotective effects, they cannot restore dead cells.”
Dr. Ross is the executive director of the IMPACT Network, a public organization studying the therapeutic properties of marijuana, making it hard to accuse her of supporting prohibition. Although she was not part of the research team for this particular study, she has conducted experiments on stimulating neurogenesis with marijuana during her work at the University of Texas and the California Institute of Technology. Despite being a strong supporter of full marijuana legalization in the U.S., her experience makes her highly skeptical about cannabinoids’ ability to stimulate nerve cell regeneration in the human brain.
“This study once again highlights the absurdity of some of the healing properties attributed to marijuana,” she told reporters. “While any study can be challenged by future research, I want to note that the experiments for this work were conducted by very experienced and talented scientists. I believe that only direct documentary evidence of brain tissue regeneration after marijuana use could refute these results.”
For their research, the scientists carefully examined brain tissue samples from 12 deceased donors. They conducted chemical analyses to look for molecules characteristic of young nerve connections, which would confirm their formation later in life. However, such compounds were not found in any of the samples. “We couldn’t detect these substances even in the freshest brain tissue samples,” says Mercedes Paredes, one of the study’s authors. “We found no physiological evidence of neurogenesis.”
Expert Criticism and Alternative Views
On the other hand, some prominent experts have criticized the new study. “I’d like to point out that this work focuses exclusively on neurogenesis in the hippocampus,” says Dr. Robert Melamede. “Many other studies published in recent years show that cannabinoid use does stimulate the formation of new nerve connections in other areas of the brain, but the authors of this study didn’t consider these factors.”
Dr. Melamede is a retired professor at the University of Colorado and is considered one of the “fathers” of molecular biology. In addition to his scientific work, he is a co-founder of the biotech marijuana company Cannabis Science Inc. He was also the first person to teach a formal university course on the therapeutic use of marijuana, which he did until his retirement in 2012. While his main expertise is in DNA and its repair processes, he is also a certified neurologist.
He notes that practical experiments with marijuana show that CBD extracts help people with Alzheimer’s disease regain cognitive abilities, suggesting that the compound may stimulate the formation of new nerve cells in different brain regions. As a reliable example, he cites the treatment of his own brother with marijuana oils.
“Sometimes, the symptoms of the disease seem to disappear, and he feels completely normal,” Melamede says. “Since he suffers from late-stage dementia associated with brain tissue loss, such health improvements can’t be a coincidence. In fact, a person who was in constant catatonia was able to interact with the world and perceive reality rationally again.”
“Either my brother got better without the formation of new neurons, which is highly unlikely, or cannabinoids really did activate neurogenesis in damaged brain tissue. I believe the latter. Despite the progression of the disease and less-than-ideal nutrition, marijuana oils truly helped him recover, as noted by many of our friends and relatives,” he continues.
By “less-than-ideal nutrition,” Melamede refers to his brother’s daily diet. In fact, the lack of information about the diet of the brain tissue donors used in the California study makes him question the validity of their analysis. He points out that eating foods high in omega-3 fatty acids (like fresh fish, olive oil, or avocado) significantly improves brain health and cell protection. These fatty acids are also components of all endocannabinoid receptors and substances in the human body, which supports the idea that marijuana’s active compounds can stimulate neurogenesis.
“At least 16% of the human brain is made up of docosahexaenoic acid, which the body cannot synthesize on its own,” Melamede says. “A diet lacking in fatty acids can lead to brain cell starvation and death, as well as slow down or stop neurogenesis.”
The Ongoing Debate
In any case, it’s important to note that the hypothesis about the human brain’s ability to regenerate lost cells is one of the oldest unresolved questions in neuroscience. Definitive conclusions about the brain’s regenerative abilities can only be made after a deeper understanding of its biology.
Meanwhile, Dr. Ross believes that doctors should not attribute properties to marijuana that have not been proven in human therapy. “In fact, claims that marijuana restores nerve cells or is a cure-all are just as unfounded as old studies discussing the risks of using the plant,” she told reporters. Of course, it’s important to remember that marijuana already has many proven therapeutic properties, which is why it is now widely used in medicine in regions where it has been legalized.
“I know that marijuana has a strong protective effect that supports the health and longevity of brain nerve connections,” says Dr. Ross. “In particular, CBD reduces swelling of the brain’s soft tissues, which not only protects them from dying but also improves memory and thinking speed in users.”