Of the 22 states in the United States that allow for the medical use of marijuana, 13 specify Alzheimer's disease (AD) as one of the approved conditions. Some studies report benefits to AD patients, but other research is inconclusive.
A suggested reason for its use is that marijuana may prove to be more effective than current treatments in breaking up the amyloid deposits that are characteristic of AD, as concluded by Lisa M. Eubanks, Ph.D. of the departments of chemistry and immunology at The Skaggs Institute for Chemical Biology and Worm Institute for Research and Medicine in La Jolla, California.
Her group found that the active ingredient of marijuana, Delta9-tetrahydrocannabinol (THC) suppressed abnormal neural activity more effectively than the current drugs used in AD as well as reducing the deposits of amyloid. Cannabinoid receptors are found throughout the central nervous system and are an important part of cognitive processing.
At this point, there are too few well-controlled studies on the efficacy of cannabis use in Alzheimer's disease to draw conclusions. In their Cochrane Database System Review, Sarada Krishnan and colleagues found only one double-blind, randomized, controlled trial investigating the efficacy of cannabinoids in the treatment of dementia. More studies are clearly warranted.
While discussing the use of marijuana treatment of dementia in "Legalization Nation," author David Downs points out that Jamaica has one of the lowest rates of dementia in the world, compared to Finland with the highest and the United States following close behind. The use of marijuana is not legal in Jamaica, but it is tolerated.
The rates of diagnosis of dementia at time of death does not have a relationship to liberal marijuana laws, or tolerance of use. While it is true that Jamaica has a low rate of diagnosed dementia with only 0.8 per thousand deaths, this may be more reflective of healthcare within that country. Those countries with a higher rate of dementia also have a longer life expectancy.
Spain has a dementia diagnosis rate at death of 18.7, Switzerland 20.0 and Finland has the highest rate at 34.9. The rate of dementia diagnosis at death is 24.8 in the United States. In Spain, life expectancy is 81.37, Switzerland is 82.28 and Finland is 79.55. The countries with the more liberal tolerance of cannabis use have lower life expectancy with Uruguay at 76.61 and Jamaica at 73.44. Those in the United States have an average life expectancy of 78.62.
Given that at this point there are no effective treatments to slow down the progression of AD, further research is important to determine how effective marijuana components can be in managing AD.
The use of marijuana in its multiple forms impacts the central nervous system in many ways. Little is known about the mechanisms impacting AD. The proposed indications for action include minimizing amyloid deposits, slowing inflammation and the influence of neural processing within the cholinergic system, all of which are lines of study for treatments specific to AD.
The use of marijuana may prove to be an important aspect of treatment and prevention of neurodegenerative diseases such as Alzheimer's disease.
