Marijuana May Block Alzheimer's

The compound may protect the brain
Source: BBC News

The active ingredient in marijuana may stall decline from Alzheimer's disease, research suggests. Scientists showed a synthetic version of the compound may reduce inflammation associated with Alzheimer's and thus help to prevent mental decline. They hope the cannanbinoid may be used to developed new drug therapies. The research, by Madrid's Complutense University and the Cajal Institute, is published in the Journal of Neuroscience.

The scientists first compared the brain tissue of patients who died from Alzheimer's disease with that of healthy people who had died at a similar age.

They looked closely at brain cell receptors to which cannabinoids bind, allowing their effects to be felt.

They also studied structures called microglia, which activate the brain's immune response.

Microglia collect near the plaque deposits associated with Alzheimer's disease and, when active, cause inflammation.

The researchers found a dramatically reduced functioning of cannabinoid receptors in diseased brain tissue.

This was an indication that patients had lost the capacity to experience cannabinoids' protective effects.

The next step was to test the effect of cannabinoids on rats injected with the amyloid protein that forms Alzheimer's plaques.

Those animals who were also given a dose of a cannabinoid performed much better in tests of their mental functioning.

The researchers found that the presence of amyloid protein in the rats' brains activated immune cells.

However, rats that also received the cannabinoid showed no sign of microglia activation.

Using cell cultures, the researchers confirmed that cannabinoids counteracted the activation of microglia and thus reduced inflammation.

Drug Target

Researcher Dr Maria de Ceballos said: "These findings that cannabinoids work both to prevent inflammation and to protect the brain may set the stage for their use as a therapeutic approach for Alzheimer's disease."

Dr Susanne Sorensen, head of research at the Alzheimer's Society, said: "This is important research because it provides another piece of the jigsaw puzzle on the workings of the brain.

"There is no cure for Alzheimer's disease, so the identification of another target for drug development is extremely welcome.

"The Alzheimer's Society looks forward to seeing further research being carried out on cannabinoid receptors as drug targets for Alzheimer's disease but would warn the public against taking marijuana as a way of preventing Alzheimer's.

"It is now generally recognised that as well as providing a 'high', long-term use of marijuana can also lead to depression in many individuals."

Different Receptors

Harriet Millward, of the Alzheimer's Research Trust, said there were two main types of cannabinoid receptor, CR1 and CR2.

"It is CR1 that produces most of the effects of marijuana, including the harmful ones.

"If it is possible to make drugs that act only on CR2, as suggested by the authors of this study, they might mimic the positive effects of cannabinoids without the damaging ones of marijuana.

"However, this is a fairly new field of research and producing such selective drugs is not an easy task.

"There is also no evidence yet that cannabinoid-based drugs can slow the decline in human Alzheimer's patients."

Quote: "We would warn the public against taking marijuana as a way of preventing Alzheimer's." -- Dr Susanne Sorensen

Source: BBC News (UK Web)
Published: Tuesday, February 22, 2005
Copyright: 2005 BBC
Website: http://news.bbc.co.uk/
Contact: newsonline@bbc.co.uk
Link to article: http://www.cannabisnews.com/news/thread20269.shtml

 

By Miranda Hitti
Source: Fox News Network

New clues about Alzheimer's disease have emerged from a Spanish study of marijuana. The drug's active ingredients - cannabinoids - help prevent brain problems seen in Alzheimer's, say the scientists. There is no cure for Alzheimer's disease, which progressively damages brain areas involved in memory, judgment, language and behavior. Alzheimer's disease is the most common form of mental decline, or dementia, in older adults.

The new study didn't test cannabinoids on people living with Alzheimer's disease. Instead, the researchers focused on human brain tissue samples and conducted cannabinoid experiments on rats.

The findings showed that “cannabinoids work both to prevent inflammation and to protect the brain,” says researcher Maria de Ceballos in a news release. That “may set the stage for [cannabinoids'] use as a therapeutic approach for [Alzheimer's disease].”

A staff member at Madrid's Cajal Institute, de Ceballos conducted the study with colleagues from nearby Complutense University. Their results appear in the Feb. 23 edition of The Journal of Neuroscience.

Marijuana, Alzheimer's Disease, and the Human Brain

The researchers studied human brain tissue samples, some of which were from deceased Alzheimer's patients and some from normal brain tissue.

The typical features seen in the brain tissue of Alzheimer's disease are called plaques. Plaques are protein clumps that are seen outside brain cells, and they have been shown to activate inflammation seen in brain tissue of Alzheimer's disease patients.

Besides the typical plaques seen with Alzheimer's disease, the brain tissues taken from Alzheimer's patients also had many fewer cannabinoid receptors.

Significant changes in the location, expression, and function of cannabinoid receptors may play a role in Alzheimer's disease, write the researchers.

That could mean that the patients had lost the capacity to experience cannabinoids' protective effects, says the news release.

Marijuana and Alzheimer's Mental Decline

The researchers also injected rats with a protein called beta-amyloid, which gave the rats an Alzheimer's-like brain condition.

Some of the same rats were also injected with a cannabinoid. For comparison, other rats got injections of an unrelated protein along with beta-amyloid.

After two months, the rats were tested for learning, memory, and mental functions. The researchers tried to train them to find a platform in a tank of water. The rats had two minutes to find the platform. If they failed, the researchers briefly put the rats on the platform. Four times a day for five days, the rats practiced.

By the fifth day, the rats that received the cannabinoid injections were able to find the platform on their own. Those that didn't get the cannabinoid injections didn't learn to find the platform.

Another interesting result also surfaced. The cannabinoids completely prevented activation of cells that trigger inflammation. These cells gather near plaque and are believed to be involved in the development of Alzheimer's disease.

“Our results indicate that cannabinoid receptors are important in the pathology of Alzheimer's disease and that cannabinoids succeed in preventing the neurodegenerative process occurring in the disease,” write the researchers in the journal.

They plan to focus future studies on a cannabinoid receptor that's unrelated to marijuana's “high,” says the news release.

By Miranda Hitti, reviewed by Brunilda Nazario, MD

SOURCES: Ramirez, B. The Journal of Neuroscience, Feb. 23, 2005; vol 25: pp 1904-1913. WebMD Medical Reference from Healthwise: “Alzheimer's Disease: Topic Overview.” News release, Society for Neuroscience.

Source: Fox News Network (US)
Author: Miranda Hitti
Published: Wednesday, February 23, 2005
Copyright: 2005 FOX News Network, LLC.
Website: http://www.foxnews.com/
Comments: foxnewsonline@foxnews.com
Link to article: http://www.cannabisnews.com/news/thread20276.shtml

 

By Ben Sills in Madrid and Ian Sample
Source: Guardian Unlimited

Scientists at one of Spain's leading research centres claimed yesterday to have found evidence that cannabis helps prevent the memory loss experienced by people suffering from Alzheimer's. The potential breakthrough in understanding a disease that affects nearly half a million people in Britain, and around nine million worldwide, was made by a team led by María de Ceballos at the Cajal Institute in Madrid. Their study seems to show that THC, the main active ingredient in cannabis, inhibits the activity of cells that cause damage to neurons in the brain.

Although the study is preliminary, it was welcomed by patient groups.

"Right now, there are no good drugs for Alzheimer's. There are some that treat symptoms but nothing that halts the disease," said Susanne Sorensen, head of research at the Alzheimer's Society.

While the beneficial effects of cannabis looked promising, Dr Sorensen cautioned that people with Alzheimer's should not start using the drug to help their memories, because of side effects.

Memory loss in Alzheimer's patients is not fully understood, but part of the problem is thought to lie with cells called microglia that surround neurons in the brain. In Alzheimer's, the activity of microglia gets out of control, damaging neurons and killing off parts of the brain. Dr de Ceballos's team conducted two separate experiments using human brain tissue and rats which showed that THC inhibits the activity of microglia, thus reducing memory loss.

Dr de Ceballos said the results showed that THC could help prevent memory loss in Alzheimer's patients, although the reasons why this might happen are still to be explored.

The next stage, she said, would be to test the rats using a synthetic equivalent of THC which inhibits the activity of microglia without intoxicating the rats as well.

"There's a long way to go before we will know if it is actually possible to stop the progression of Alzheimer's," she said.

Source: Guardian Unlimited, The (UK)
Author: Ben Sills in Madrid and Ian Sample
Published: Thursday, February 24, 2005
Copyright: 2005 Guardian Newspapers Limited
Contact: letters@guardian.co.uk
Website: http://www.guardian.co.uk/
Link to article: http://www.cannabisnews.com/news/thread20277.shtml