Marijuana Ingredient May Help Alzheimer's
Chemical Counters Brain Problems in Alzheimer's Disease,
Says Spanish Study
This article is from the WebMD Medical News Archive
Feb. 23, 2005 -- 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.
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.
By Miranda Hitti
WebMD Medical News