More Evidence Suggests Marijuana Slows Alzheimer's

Marijuana might contain compounds that slow memory loss in Alzheimer's patients, according to a new study that bolsters other research suggesting potential brain benefits of pot.

Old rats treated with a synthetic compound similar to marijuana got smarter, said Gary Wenk, study co-author and a professor of psychology at Ohio State University.

"The compound substantially improved the memories of the older rats," Wenk said. "These animals were able to hold on to key details of a specific task. Untreated older rats, on the other hand, were not."

The key seems to be in marijuana's anti-inflammatory effects.

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

Wenk notes that other studies indicate that people who regularly smoked marijuana in the 1960s and '70s rarely develop Alzheimer's disease. But there is of course a downside. Research has also shown that years of heavy marijuana use, consisting of four or more joints a week, can impair memory, decision making, and the ability to pay attention to more than one thing at a time.

"We don't use marijuana in our experiments because we're trying to find a compound that isn't psychoactive," Wenk said.

The synthetic marijuana-like compound used in the study, called WIN-55212-2, decreased inflammation in the brains of both young and old rats and helped them navigate a maze better.

The findings were presented today in Atlanta at the annual Society for Neuroscience meeting.

A separate study earlier this month found that the active ingredient of marijuana could be considerably better at suppressing abnormal clumping of malformed proteins in the brain that is a hallmark of Alzheimer's.

• Top 10 Mysteries of the Mind
• Brain and Body Shrink Before Alzheimer's Sets In
• Why Great Minds Can't Grasp Consciousness
• What Causes Dejà Vu?