MARIJUANA'S ACTIVE CHEMICAL MAY BE ALZHEIMER'S FIGHTER

U.S. Tests Suggest THC Stops Damaging Plaque

THC, the active component in marijuana, may protect the brain from the
ravages of Alzheimer's disease, U.S. scientists reported.

In lab experiments, investigators from Scripps Research Institute in
La Jolla, California, found THC appears to block an enzyme in the
brain that causes plaque to form more effectively than approved drugs.

Alzheimer's is the leading cause of dementia among the elderly. An
estimated 290,000 Canadians over 65 have the disease -- a number
expected to double over the next two decades. Women account for more
than two-thirds of cases, according to the Alzheimer Society of Canada.

The progressive, degenerative brain disease has no cure.

"I'm not at all suggesting you smoke pot," said Kim Janda, a professor
of chemistry and immunology at Scripps, who is working on developing
vaccines against cocaine, nicotine and other drugs of abuse.

But his team's work may provide a lead for new and more effective
medications, he said.

"I think it could have strong implications that molecules like THC
could prevent fibrils or plaque formation."

It's the latest study to suggest the compound that produces a high
might also be protective to the brain. Marijuana-like compounds are
already being tested in mice against the fatal brain disease ALS, or
Lou Gehrig's disease.

People with Alzheimer's have low levels of acetylcholine, a brain
chemical believed to be important for learning and memory.

Existing drugs help ease symptoms of the disease by blocking an enzyme
that breaks down acetylcholine.

Dr. Janda's team found THC (delta-9-tetrahydrocannabinol) did the same
but at lower concentrations. It also "blunted" the formation of
fibrils, or long, thread-like fibres that get woven into healthy brain
cells, eventually choking them.

The researchers believe they've found a way THC "can directly impact
Alzheimer's disease pathology." Their work is published in Molecular
Pharmaceutics.

There are important limitations to the study. The experiments didn't
involve tests on human cells, or even mice (it's one of the reasons
why Dr. Janda said they were turned down by several other bigger
journals.) Instead, they used synthetic versions of a peptide that
causes brain plaques to form.

"The definitive study would be to get animals that have been bred to
have early-onset Alzheimer's and look at the long-term effects of
chronic THC administration," Dr. Janda said.

As well, there is still debate over what causes Alzheimer's, and just
how important plaques are in causing the disease. "I think most people
believe it is a key component," he said.