Pot may hold Alzheimer's promise

Published: Monday, October 09, 2006
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, Calif., found THC appears to block an enzyme in the brain that causes plaques to form better than currently 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.

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 fibers 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 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," 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," Janda said.

According to the Alzheimer Society of Canada, symptoms of the illness including forgetting simple words, forgetting things more often, especially things that have happened recently, and trouble performing familiar tasks.

skirkey@canwest.com

http://www.canada.com/vancouversun/n...75ee39&k=33721

Pot may be boost to older brains



BY JORDAN LITE
DAILY NEWS STAFF WRITER

Stoners who spent the 1960s and '70s in a haze could find themselves surprisingly lucid in old age: the marijuana they smoked helps protect against Alzheimer's disease, a new study found.
Anti-inflammatory compounds in pot deflect the memory loss associated with the illness and could ultimately slow its progression, said psychology Prof. Gary Wenk of Ohio State University.

Wenk gave old rats - who, like humans, tend to get lost as they age - a synthetic form of marijuana. The ones given the drug found their way through a maze more easily.

"That's not going to cure Alzheimer's disease, but it's going to help a lot because by reducing inflammation we're going to rescue some neurons - we're going to help you not decay so fast," said Wenk, who presented his findings yesterday at the Society for Neuroscience meeting in Atlanta.

But scientists still need to find a compound that reduces brain inflammation without triggering a high, said Wenk, whose research is funded by the federal government, which has long criminalized marijuana.

"You can't add a high onto a dementia. You're just going to make the person more impaired," he said.

The drug was effective in older rats with modest memory impairments, but it's not yet clear when humans would most benefit from taking a nonpsychoactive form of it.

Grateful Dead-era potheads offer a clue, though.

"There's this fear as the Baby Boomers get older that there's going to be more and more people with Alzheimer's," Wenk said.

"It may be we're surprised by the fact that this illicit compound used decades ago might alter how many people get diagnosed."

http://www.nydailynews.com/front/sto...p-389669c.html