Everybody knows a forgetful stoner, but research suggests that low doses of marijuana could be good for memory, and even help prevent Alzheimer's disease.

When given a compound similar to THC, the psychoactive ingredient in marijuana, rat brains displayed reduced levels of inflammation associated with Alzheimer's disease. The drug also stimulated the production of proteins associated with memory formation and brain cell growth.

"Everyone is aware that smoking too much marijuana impairs memory," said Ohio State University psychologist Yannick Marchalant. "Our work stays on the safe side — doses that we know are not going to impair memory, but improved it."

Marchalant and fellow OSU psychologist Gary Wenk previously showed that marijuana can improve memory formation in rats. The latest research, presented at this week's Society for Neuroscience annual meeting, provides a detailed look at THC's effect on the brain.

It's far too soon to extrapolate the findings directly to people, but the researchers hope it will inform the development of targeted (and legal) drugs — and in the meantime, they say, there might be a role for marijuana in preventing age-related neurodegeneration.

"What we're looking at is preventing the inflammation-induced impairment of memory that you see in normal and pathological aging,"

said Marchalant. "We'll try to find safe drugs that you can use 10 or

20 years beforehand."

The compound used by the researchers isn't identical to THC, but marijuana likely produces some of the same effects, he said.

Marchalant cautioned that any benefits wouldn't be experienced by people whose brains have already started to deteriorate, nor those whose brains are still forming. But for adults looking to prevent dementia, marijuana could play a role — albeit at very small doses, well below the level of psychoactivity.

"It will take the recreational use out of it," said Marchalant, who made a rough extrapolation from rat doses to a single human puff of pot.

"It's hard to say, no you shouldn't," to someone who wants to self-medicate, said Marchalant, but he stressed that the research is still highly experimental.

"We still have a lot of work ahead to do in animals," he said.

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