Marijuana Has Potential to Treat Alzheimer's, Says Salk Institute Study

Alzheimer's is a chronic neurodegenerative disease that slowly shuts down the brain and eventually leads to death. But a new study gives patients and their families hope that marijuana could help.

Researchers at the Salk Institute of Biological Studies published a study in the June journal of Aging and Mechanisms of Disease announcing the discovery of a compound present in marijuana that triggers the removal of beta-amyloid protein from neurons. In layman's terms, that means cannabis could help remove deadly plaque accumulation from the nerve cells.

"It is reasonable to conclude that there is a therapeutic potential of cannabinoids for the treatment of Alzheimer's disease," writes David Schubert, senior researcher and a professor at Salk.

Little is known about the illness, including what causes it, but that hasn't stopped scientists from researching how neurons deteriorate in the brain and trying to determine how to slow down or stop that process. Alzheimer's is the sixth-leading cause of death in the U.S.; the number of patients diagnosed with the disease is expected to more than double by 2050.

Approximately 5.4 million Americans are currently suffering from Alzheimer's. That's a higher number than those currently living with a breast cancer diagnosis or who have died from heart disease or car accidents in the past year — combined.

A majority of those diagnosed with Alzheimer's are over the age of 65. However, 200,000 of those afflicted with the disease are diagnosed with younger-onset Alzheimer's and are under the age of 65.

Using a process that exposes the brain's nerve cells to tetrahydrocannabinoil, or THC, reduced the effects of Alzheimer's, eliminating the inflammatory response from the cells caused by the protein, the study reported.

"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 Antonio Currais, one of the authors of the study.

Since the research was conducted on neurons grown in the lab, Schubert stresses that this method of treatment would still need to be tested in clinical trials.

The idea that Alzheimer's can be treated by marijuana is not a new one. In a 2014 review of existing research on the drug, Dutch scientists found two independent studies that concluded that THC can be useful in treating symptoms of dementia. 

Then, earlier this year, scientists conducting a small study of eleven people came to a similar verdict when they found negative symptoms like "delusions, agitation (and) aggression, irritability, apathy, sleep and caregiver distress" all decreased when the patients used marijuana.

"Although other studies have offered evidence that cannabinioids might be neuroprotective against the symptoms of Alzheimer's, our study is the first to demonstrate that cannabinoids affect both inflammation and amyloid beta accumulation in nerve cells," Schubert says.

These studies all focused on treating Alzheimer's, but other studies have found that cannabinoids can play a role in reducing general inflammation in the central nervous system. The endocannabinoid system, named after the marijuana plant Cannabis sativa, has shown positive results in helping cells communicate and coordinate. 

Alzheimer's patients lose more and more of their memories and mental abilities as neurons in the brain die, so by lowering brain inflammation and decreasing the number of dying nerve cells, this treatment could help the brain balance itself and keep more cells alive longer.
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Kate McKee Simmons interned at the National Catholic Reporter, was a reporter for the New York Post, and spent a brief stint in Israel learning international reporting before writing for Westword.