New Research Shows Marijuana Compounds Could Protect the Brain From Alzheimer's

Getty Images

Scientists are searching for ways to prevent Alzheimer's disease, a form of dementia that affects more than 5 million Americans and is the sixth-leading cause of death among U.S. adults.

It turns out weed may help.

The latest research: According to new findings out of the Salk Institute, tetrahydrocannabinol and other compounds found in marijuana may help remove amyloid beta — a toxic protein associated with Alzheimer's disease — from nerve cells in the brain. 

"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," the paper's senior author, Salk Professor David Schubert, said in a statement

Senior author David SchubertSource: Salk Institute
Senior author David Schubert  Salk Institute

How it works

Let's start with those "toxic proteins." Though scientists don't have a definitive cause of Alzheimer's disease, they suspect it's partly to do with plaques: Clumps of a "sticky" protein — amyloid beta — that develop between neurons in the brain, according to the Alzheimer's Association

Using lab-grown tissue, the Salk Institute researchers found that higher levels of amyloid beta led to increased inflammation — and, in turn, cell death. 

High levels of amyloid beta in the brain are associated with Alzheimer's disease.Source: Evan Vucci/AP
High levels of amyloid beta in the brain are associated with Alzheimer's disease.  Evan Vucci/AP

Here's where the weed comes in: Our bodies naturally produce compounds called endocannabinoids, which facilitate signaling in the brain. According to the new study, endocannabinoids also protect nerve cells from amyloid beta and inflammation.

THC and other cannabinoids were found to have the same effect. 

"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," the paper's first author, Antonio Currais, said in a statement.

"I think it is exciting, to tell you the truth," Keith Fargo, director of scientific programs and outreach at the Alzheimer's Association — which funded research that informed this study — said in a phone call Wednesday. 

Currently, there are five drugs approved by the Food and Drug Administration to treat the symptoms of Alzheimer's disease. But "they don't actually do anything to slow down the disease's process," Fargo said. "They help with the condition for a little while, but the disease progresses unabated."

"Really, the holy grail is to find something that would stop the progress of the disease, or at least slow it down," he continued. The Salk Institute's research is a step in that direction.

THC may help protect against inflammation and amyloid beta.Source: Justin Sullivan/Getty Images
THC may help protect against inflammation and amyloid beta.  Justin Sullivan/Getty Images

Weed and Alzheimer's disease

A number of other studies have explored marijuana's potential role in fighting Alzheimer's disease. Research like this 2014 study and this 2006 study found THC inhibited amyloid beta aggregation.

Still, it'll be some time before America's Alzheimer's patients can put the Salk Institute's findings to the test. As the press release points out, the research team used "exploratory laboratory models" — and "the use of THC-like compounds as a therapy would need to be tested in clinical trials."

If the therapy works in humans, "it probably won't be the whole plant marijuana that's recommended," Fargo cautioned. "Not everybody wants to have that psychoactive experience you have with marijuana use." 

Instead, pharmaceutical companies could create treatments that target the brain's cannabinoid system — and don't get patients stoned.

It may be a far off goal — but it's still an important one, Fargo said.

"There are 5 million Americans today that have dementia from Alzheimer's disease," he said. "That's just going to increase unless we find something that can slow down the progress of the disease."

Read more:
An Unexpected Therapy for Alzheimer's Is Getting Major Traction
• Bacteria From Guam's Palm Trees Could Unlock a Solution to Alzheimer's
• Playing This Game for Just 2 Minutes Could Help Doctors Diagnose Dementia