October 24, 2006
The active ingredient in marijuana that produces its "high" may also help to stave off Alzheimer's disease, new research suggests. The substance, called THC, helps to preserve levels of a natural brain chemical called acetylcholine that is important for memory and learning. People with Alzheimer's have low levels of acetylcholine, and many of the currently available drugs for the disease target an enzyme to keep this brain chemical from breaking down.
In laboratory experiments, researchers from the Scripps Research Institute in La Jolla, CA, found that THC, or tetrahydrocannabinol, preserves brain levels of acetylcholine better than some of the current medications currently available to treat Alzheimer's. These popular drugs, which include Aricept and Cognex (also known as cholinesterase inhibitors), may ease some symptoms and slow progression of the disease in some people but do not stop its unrelenting downward course.
THC also appears to help prevent the buildup of damaging beta-amyloid plaque, at least in laboratory studies. In the experiments, THC was very effective in reducing plaque buildup, whereas the Alzheimer's drugs (cholinesterase inhibitors) did little to prevent the buildup of the toxic clumps.
Marijuana is legal in some states for medical purposes. It may be effective for some forms of glaucoma, an eye disease that can lead to blindness. It may also help to relieve nausea and vomiting and other side effects due to cancer treatments or AIDS drugs. However, heavy marijuana use has also been linked to poor memory and impaired decision making.
Doctors do not advise those with Alzheimer's to begin smoking pot. Because of its intoxicating effect, marijuana is likely to cause confusion and disorientation in people with Alzheimer's. Medical researchers are, however, looking into developing drugs related to THC that may be effective treatments for Alzheimer's, or which may delay onset of the disease in high-risk individuals. Earlier research in rats has suggested that manmade drugs resembling THC may reduce inflammation and slow the mental decline associated with Alzheimer's. More study of the potential benefits is needed.
The findings appeared in the scientific journal Molecular Pharmaceutics, a publication of the American Chemical Society. For more information on emerging treatments for Alzheimer's disease, visit www.ALZinfo.org.
Kim Janda, Lisa M. Eubanks, Claude J. Rogers, et al: "A Molecular Link Between the Active Component of Marijuana and Alzheimer's Disease Pathology." Molecular Pharmaceutics, August 9, 2006.