An active compound found in the cannabis plant called tetrahydrocannabinol, more commonly known as THC, has recently been found to promote the removal of toxic clumps of amyloid beta protein in the brain, which are thought to be precursors to Alzheimer’s disease.
These findings support the results of previous studies, which found evidence of the protective effects of cannabinoids, including THC, on patients with the neurodegenerative disease.
According to senior paper author David Schubert, of the Salk Institute for Biological Studies in California, “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.”
Alzheimer’s disease is a progressive brain disorder that eventually leads to extreme memory loss and can severely interfere with a person’s ability to care for themselves and perform routine tasks. According to the National Institutes of Health, it affects more than 5 million Americans and is a leading cause of death. It is also the most common cause of dementia. Incidence of the disease is expected to triple over the next 50 years.
The researchers tested the effects of THC on human neurons grown in the lab that mimic the effects of Alzheimer’s disease within the brain. Researchers remain unsure of what exactly causes the disease, but it’s thought to occur from a buildup of lesions, amyloid plaques, and neurofibrillary tangles. Amyloid plaques sit between the neurons as dense clusters of beta-amyloid molecules, which are a sticky type of protein that can easily clump together, and neurofibrillary tangles are caused by defective tau proteins that clump into thick, insoluble mass inside the neurons.
Currently, it is unclear why these lesions appear in the brain in the first place, but there have been some studies that link inflammation of the brain tissue to the proliferation of the plaques and neurofibrillary tangles. Researchers hope that if they can find a way to clear out the plaques as well as reduce brain tissue inflammation, they will be closer to creating an effective treatment for Alzheimer’s disease.
“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,” says one of the team, Antonio Currais.
“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.”
In 2006, researchers at the Scripps Research Institute were able to find that THC actually inhibits the formation of amyloid plaques by blocking the enzyme in the brain that is responsible for producing them.
Another study out of Australia took mice that were bred to mimic symptoms of Alzheimers and gave them CBD from cannabis. The non-psychoactive cannabinoid caused a drastic improvement in memory within the mice tested. Although further study is necessary, early results are showing signs of memory improvement, and physical results will be tested next.
“Cannabinoids are the first and only class of drugs that have ever been effective,” said Gary Wenk, a professor of neuroscience, immunology, and medical genetics at Ohio State University.
While this research has exciting potential for future treatments, so far it has only been demonstrated in neurons in the lab and not on an actual human brain. The next step for Schubert and his team will be to observe the link between THC and reduced plaque buildup and inflammation in a clinical trial. It is important to realize that there is hope, however, to treating this increasingly common degenerative disease.
