The discovery was made with lab-grown human neurons that mimic the effects of Alzheimer’s.
In a new study at the Salk Institute for Biological Studies in California, researchers found that tetrahydrocannabinol (THC), the active compound in marijuana, appears to remove toxic buildups of amyloid beta protein in the brain — the brain plaques which are linked with the progression of Alzheimer’s disease.
"Although other studies have offered evidence that cannabinoids might be neuroprotective against the symptoms of Alzheimer's, we believe our study is the first to demonstrate that cannabinoids affect both inflammation and amyloid beta accumulation in nerve cells," team member David Schubert from the Salk Institute said in a press release.
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Reporting their work in the journal Aging and Mechanisms of Disease, the team tested THC’s effect on human neurons that were grown in the lab to mimic the effects of Alzheimer’s disease.
High levels of amyloid beta are associated with inflammation and higher rates of neuron death, and the researchers demonstrated that exposing the cells to THC lowered the inflammatory response as well as the levels of amyloid beta protein, enabling the nerve cells to live.
"Inflammation within the brain is a major component of the damage associated with Alzheimer's disease, but it has always been assumed that this response was coming from immune-like cells in the brain, not the nerve cells themselves," first author Antonio Currais, a postdoc researcher in Schubert's laboratory, said in the release.
"When we were able to identify the molecular basis of the inflammatory response to amyloid beta, it became clear that THC-like compounds that the nerve cells make themselves may be involved in protecting the cells from dying."
Receptors in the brain can be activated by endocannabinoids, which are a class of molecules made in the body that signal between brain cells. THC works similarly to endocannabinoids by activating the same receptors in the brain, which produces the drug’s psychoactive effects.
Further, the researchers say that physical activity leads to the production of endocannabinoids, and some studies have shown that exercise may slow the progression of Alzheimer’s.
Before getting too excited, it’s important to note that these results were derived from exploratory laboratory models, so the researchers still have to test whether the findings would translate over to humans in a clinical trial.
Thankfully, they may have already found a way to avoid the tricky regulations surrounding marijuana research in the US, thanks to a drug candidate called J147. In separate research, the team found that J147 acts similarly to THC by removing amyloid beta from nerve cells and reducing the inflammatory response, so the researchers may be able to test out these effects in humans without the US government imposing its strict rules around cannabis research.
Alzheimer’s disease affects more than five million Americans, and the National Institutes of Health says it is a leading cause of death. Given that the rate of Alzheimer’s is expected to triple in the next 50 years, any research that gives insight into how to potentially counter its effects can serve to help.