Cannabis May Cut Alzheimer's Risk

Oct. 19, 2006 — For those who have inhaled, there may be some good news: Marijuana use may cut the risk of developing Alzheimer's disease by reducing inflammation in the brain, researchers reported this week.

The findings, released at the Society for Neuroscience meeting in Atlanta, may explain studies showing those who regularly used marijuana in the 1960s and 1970s are now less likely to develop Alzheimer's disease than their non-smoking contemporaries.

Under a National Institutes of Health grant, researchers used a synthetic drug similar to marijuana to treat rats with brain inflammation typically associated with Alzheimer's disease, a form of dementia that afflicts 4.5 million people in the United States alone.

"Inflammation in the brain is part of aging," said Ohio State University researcher Gary Wenk. "It happens to almost all of us as we age. But in some cases, this inflammation gets out of hand and causes serious damage."

The compound, called WIN-55212-2, was given to some rats daily for three weeks. The rodents then were made to navigate a water maze, a typical test for memory and learning.

Both young and old rats given the synthetic marijuana did better on the test, said Wenk, a psychology and neuroscience researcher who headed the study.

"Old rats tend to be pretty bad at navigating the maze," Wenk said. "It's kind of like an elderly person trying to find his way around a house that he's not familiar with."

After the tests, the rats' brains were analyzed and researchers found less Alzheimer's-type inflammation in the treated animals. The most pronounced differences were in the older rats, Wenk said.

"It's a pretty good prediction of how a human would respond to this drug," he said.

The compound is not a candidate for human use because it contains substances that could trigger psychoactive effects. Wenk and his team hope to develop a drug with just the anti-inflammatory properties of marijuana.

"We don't use marijuana in our experiments because we're trying to find a compound that isn't psychoactive," Wenk said. "Using synthetic compounds may eventually help us to separate the beneficial effects from the psychoactive effects."

The studies also found that caffeine helps reduce brain inflammation as well, but mostly in the younger rats.