Marijuana could help reduce memory loss in old age and fight Alzheimer's Disease, scientists have found.
By Richard Alleyne, Science Correspondent

Contrary to the common belief that smoking the drug destroys memory, researchers have found that it could actually keep the brain young.

The team at Ohio State University found that specific elements of marijuana can be good for the ageing brain by reducing inflammation there and possibly even stimulating the formation of new brain cells.

The research suggests that the development of a legal drug that contains certain properties similar to those in marijuana might help prevent or delay the onset of Alzheimer's disease.

Though the exact cause of Alzheimer's remains unknown, chronic inflammation in the brain is believed to contribute to memory impairment.

Any new drug's properties would resemble those of tetrahydrocannabinol, or THC, the main psychoactive substance in the cannabis plant, but would not share its capability to produce a "high".

"Could people smoke marijuana to prevent Alzheimer's disease if the disease is in their family? said Gary Wenk, professor of psychology at Ohio State University and principal investigator on the research.

"We're not saying that, but it might actually work. What we are saying is it appears that a safe, legal substance that mimics those important properties of marijuana can work on receptors in the brain to prevent memory impairments in ageing. So that's really hopeful."

The research, which was presented to the Society for Neuroscience, involved giving rats a constant dose of a cannabis derivative for three weeks.

A control group of rats received no intervention. In follow-up memory tests, in which rats were placed in a small swimming pool to determine how well they use visual cues to find a platform hidden under the surface of the water, the treated rats did better than the control rats in learning and remembering how to find the hidden platform.