This week scientists found evidence that the psychoactive ingredient in marijuana, tetrahydrocannabinol (THC), may be able to remove the buildup of a toxic protein linked to Alzheimer’s. It’s good news for the fastest growing group of marijuana users—seniors—and gives those above the age of 50 who haven’t come out of the pot closet a good reason to do so.
The study, published in the June edition of the Aging and Mechanisms of Disease journal, was performed by experts at the Salk Institute. Professor David Schubert, the lead researcher on the project, has long been searching for a way to treat the incurable disease. To perform the experiment, Schubert and his team grew neurons in a lab and manipulated them into producing large amounts of beta amyloid—a hallmark symptom of Alzheimer’s.
Normal brains metabolize the protein, using an enzyme to “wash it” from the brain. Those with Alzheimer’s, for reasons that are still unclear, do not. Left untouched, the stringy “garbage” protein clumps together and forms plaques in the brain, which interfere with cognition. When the scientist introduced THC into the nerve cells, these plaques disappeared—as did the inflammation that they were causing.
The THC reportedly worked by activating “receptors” in the brain which are used for intercellular signaling, communicating to cells that the protein should be broken down.
Antonio Currais, a Salk researcher in Schubert’s lab and one of the authors on the paper, highlighted the importance of the discovery. "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," said 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."
Cannabis has long been shown to reduce inflammation, with some scientists suggesting that it be used as a novel anti-inflammatory drug. Researchers explained this in a study from 2010, writing that the drug’s active ingredients “control the cellular pathways leading to inflammatory response.” These properties are part of what makes cannabis an effective treatment for autoimmune disorders, as well as chronic pain.
Many studies have explored its benefits in this area, but few have investigated its potential to have an impact on those with Alzheimer’s. It’s a population that’s desperately in need of solutions.
Discovered in the early 1900s, Alzheimer’s is a disease that still mystifies scientists. A progressive neurodegenerative disease, it begins with short term memory loss and ends with severe—and fatal—brain damage. More than 5 million Americans are currently living the disease, which (along with other types of dementia) kills one in three seniors.
While more than 44 million people suffer from the disease worldwide, it is particularly prevalent in the United States, affecting one in nine Americans over the age of 65. Beyond the implications for health, the condition takes a major toll on the economy. In 2016, it will cost the U.S. approximately $236 billion.
The mortality rates associated with the disease are grim, generally averaging about four to eight years. Although a wealth of research has been performed on the disease, the search for a cure is far from over. In the interim, the number of those affected—in part due to the increasing senior population—has soared. In the past decade alone, the number of deaths from Alzheimer’s has increased 71 percent.
As of now, there is no known cause, treatment, or cure. Without one, there may be more than 16 million adults suffering from it by 2050.
Research on the beta amyloid protein and its connection to the disease has uncovered potential contributing factors. One study from last August suggested that the build-up may revolve around a lack of sleep, the time at which most brains rid themselves of the toxin. Another in May, from the American Association for the Advancement of Science, proposed that the buildup of the protein may signal an infection instead.
Rather than analyzing the potential cause of the buildup, the Salk researchers aimed to find a way to eliminate it once it is there. "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," said Schubert.
The theory, to be sure, needs much more thorough testing before it can be deemed a potential treatment option. But for those who worry about the disease, there’s never been a better time to jump on the marijuana train.