In rats with brain inflammation due to natural aging or in response to an artificial inflammatory stimulus, treatment with a synthetic compound akin to marijuana markedly reduced brain inflammation and slowed memory loss.

“It will be important to find a drug that reduces brain inflammation, but that does not produce the classic ‘high’” that marijuana does, Dr. Gary L. Wenk from Ohio State University in Columbus told Reuters Health.

Wenk said his research is motivated by evidence that brain inflammation contributes to many age-related degenerative brain disorders, including Alzheimer’s disease. “This inflammation appears to be present many, many years prior to the onset of the symptoms,” he said.

In rats with brain inflammation that mimics that seen in patients with Alzheimer’s disease, Wenk and his associates discovered that daily treatment with a synthetic marijuana-like drug called WIN reduced inflammation in the brain and improved memory.

On tests of memory performed during the third week of treatment, WIN-treated older rats were able to hold on to key details of a specific water maze task that they’d been taught, whereas the untreated older rats were not.

Younger WIN-treated rats also navigated the water maze faster than non-treated younger rats, but the difference wasn’t as remarkable as that of the older group, perhaps because of the lack of age-related changes in the brains of the younger rats.

Wenk presented his group’s research today at the Society for Neuroscience annual meeting in Atlanta.

Studies have shown that people who routinely use anti-inflammatory drugs, particularly the ones that cross the blood brain barrier, have a significantly reduced incidence of Alzheimer’s disease.

Marijuana has strong anti-inflammatory effects. “This is why I believe that people who used marijuana a few decades ago are much less likely to develop any disease, such as Alzheimer’s, that relies upon the slow development of brain inflammation,” Wenk told Reuters Health.

“What we need now is to better understand the mechanisms underlying this effect,” Wenk said. Increased efforts to find or create a drug with the anti-inflammatory but not the psychoactive properties of marijuana are also in order.