November 17, 2009 – 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 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.
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. Video: