Study: Medical marijuana may prevent Alzheimer’s disease

In Alzheimer's, Top Stories by Dr. Tim Sandle, Ph.D.

Pioneering new research suggests that smoking marijuana before the onset of certain types of dementia, such as Alzheimer’s disease, can slow down the development of degenerative conditions. Taken at the right age and with sufficient frequency, smoking marijuana could prevent the symptoms of Alzheimer’s disease from manifesting, to the degree that a person could die from old age before the condition fully sets in.

This is the conclusion of a recent study conducted by Professor Gary Wenk. To find out more about the research and the use of medical marijuana to prevent conditions like Alzheimer’s disease, The Medical Marijuana Review took the opportunity to talk with Professor Wenk about his findings.

Wenk is a scientific researcher based at the Department of Psychology of Ohio State University, and is a Fellow at the American Association for the Advancement of Science, where he has been acknowledged for distinguished contributions in the areas of neuropharmacology, neurodegenerative diseases and neuroinflammatory processes.

The core focus of Wenk’s work is the study of the consequences of chronic brain inflammation as a result of normal aging and of Alzheimer’s disease. His current research centers on how Alzheimer’s disease is caused by inflammation to the brain.

As he explains: “Inflammation is now thought to underlie most age-associated neurological diseases.  Chronic brain inflammation does not cause these diseases; it simply magnifies the pathology and induces it to progress. The inflammatory process is likely initiated by mutant proteins that appear soon after birth. Alzheimer’s disease is now thought to begin very early in life; it simply takes many decades for the symptoms to appear.”

Current medical opinion is that, over many years, a protein called amyloid-beta (Aβ) forms sticky “plaques” in the brains of people with Alzheimer’s disease, ultimately killing the surrounding neurons and causing memory loss and other cognitive problems.

In his search for a way to stop the condition’s progress, Wenk is exploring the ability of cannabinoids to reduce inflammation inside the brain.

Cannabinoids are a group of compounds present in marijuana. They affect cannabinoid receptors such as CB1, which is found in the brain. This can help to regulate aspects of the brain’s inflammatory response, including halting the release of pro-inflammatory chemicals.

He explains how he came to start looking at cannabinoids: “I have been testing experimental compounds for drug companies for many years; all of them failed to provide benefit in aged brains. I was looking for a lipid-soluble, safe anti-inflammatory and I was aware that many patients with multiple sclerosis have claimed that small daily doses of marijuana helped them to deal with their symptoms, which are due to inflammation. So I decided to test cannabinoids.”

For his most recent investigation, Wenk used an animal model to explore how cannabinoids can slow down the physiological conditions that can cause Alzheimer’s. To show this, he “treated young and aged rats with daily, very low, doses of cannabinoid receptor agonists and then studied the effects upon behavior, brain chemistry and pathology.”

the Department of Psychology of Ohio State University

Professor Gary Wenk of Ohio State University

The experimental results showed that cannabinoids help the brain to compensate for the presence of chronic neuroinflammation; specifically, slowing the development of inflammation in the hippocampus region of the brain (the part of the brain that is involved in memory forming, organizing and storing). This, in theory, would slow down the development of Alzheimer’s disease.

Summing up the experiment, Wenk concluded: “My evidence shows that it is possible to delay the onset of symptoms related to the pathology of normal aging.”

Although a synthetic compound was used, Wenk is of the view that “there is every reason to believe that the same benefits would be obtained from the natural compounds.” That is, the same beneficial effect should be produced through the use of medical marijuana.

Given that medical marijuana should work in the same way to reduce brain inflammation, when it comes to the best time to start taking medical marijuana, the professor is of the view that people could choose to start at any time: “My research suggests that it is never too early, or too late, in life to begin using very low daily doses, i.e., one puff per day.”

The importance of cannabinoids in treating brain inflammation probably extends beyond Alzheimer’s to “any disorder that includes chronic neuroinflammation, such as MS, Parkinson’s disease, AIDS, ALS, [or] traumatic brain injury,” Wenk says. “The list gets longer every year as we begin to understand the widespread role of inflammation in the brain.”

In terms of any psychiatric concerns in relation to taking marijuana, Wenk regards this as an issue for the individual:

“This question is relevant when using any psychoactive drug; the problem is that there is no way to predict who is likely to show psychiatric reactions. Some studies claim yes, while others claim no. The answer that I give my students is that if they carry a genetic predisposition, then they might develop psychiatric symptoms; however, it is currently impossible to know whether one carries a genetic predisposition because the genes have never been identified. Therefore, it’s genetic roulette.”

Moving on to public policy, Wenk notes a shift change in the attitude of the public and politicians to the use of marijuana for medical reasons. “The next generation of policymakers will not view cannabinoids in the same fearful way that today’s policymakers do. In the past three decades, I’ve witnessed a significant shift in attitude of my students.  Even students who do not use cannabinoids do not care whether other people do. They are all far more tolerant of cannabinoid use. When the current generation of policymakers leave office, they will be replaced by a very different group of opinions.”

In summary, Wenk’s important studies indicate that if cannabinoids are taken early enough in life, they slow down the tendency for inflammation in the brain to occur and can delay the onset of a range of age-related degenerative conditions such as Alzheimer’s.

As to the future, Wenk thinks that more research should be undertaken into the medical properties of marijuana. He notes, “There is so much more to discover about how the components of this plant act in aggregate in addition to the actions of the individual components of the plant.”

Photo courtesy Alyssa L. Miller