Marijuana may block Alzheimer's
Lloyd Jeffrey Mallan
Feb 24, 2005 00:46 PST
Marijuana may block Alzheimer's
The compound may protect the brain
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
They hope the cannabinoid 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.
We would warn the public against taking marijuana as a way of
Dr Susanne Sorensen
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
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
Using cell cultures, the researchers confirmed that cannabinoids
counteracted the activation of microglia and thus reduced inflammation.
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
"It is now generally recognised that as well as providing a 'high',
long-term use of marijuana can also lead to depression in many
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
"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."
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