A new study suggests that compounds related to marijuana may help limit memory loss in Alzheimer’s disease.
Alzheimer’s is the leading cause of dementia among the elderly, and with the ever-increasing size of this population, cases of Alzheimer’s disease are expected to triple over the next 50 years. The development of treatments that slow or halt the disease’s progression has become imperative both to improve patients’ quality of life and to reduce the health care costs attributable to Alzheimer’s disease.
As marijuana has strong anti-inflammatory effects, researchers from Ohio State University predicted a link to the progression of Alzheimer’s disease, which is associated with chronic inflammation.
According to researcher Gary Wenk, Ph.D., “inflammation in the brain is part of aging. It happens to almost all of us. But in some cases, this inflammation gets out of hand and causes serious damage.”
The team gave WIN-55212-2, a synthetic drug similar to marijuana, to rats and found it improved memory and helped to control inflammation both in young and old animals. However, it could still trigger a high, so the team are trying to find a compound that isn’t psychoactive. The findings were presented at October’s annual Society for Neuroscience meeting in Atlanta.
There is some evidence to suggest that people who regularly smoked marijuana in the 1960s and 1970s rarely develop Alzheimer’s disease, but Wenk does not recommend that Alzheimer’s patients start using marijuana.
“Patients would have to be so careful not to get too much,” he said. “That would only worsen the symptoms of their dementia.”
Cannabis comprises a complex mixture of chemicals with possibly opposing effects.
Nevertheless, research is being undertaken by experts including Lisa M. Eubanks, Ph.D., of the Scripps Research Institute in California. Earlier this year, her team discovered a new molecular mechanism through which cannabinoid molecules may affect the progression of Alzheimer’s.
A 2005 study from Spain found that cannabinoids may stall the decline from Alzheimer’s through their effects on brain function. A team from the Cajal Institute and Complutense University in Madrid looked at the effects of cannabinoids on rats and human brain tissue.
They found that there was “dramatically reduced functioning of cannabinoid receptors” in the brain tissue of patients who died from Alzheimer’s disease, meaning that patients had lost the capacity to experience cannabinoids’ protective effects compared with the healthy people who had died at a similar age. In rat experiments, the team found that cannabinoids could prevent the neurodegenerative process occurring in the disease.
However, other experts have warned that some compounds in cannabis, including THC, interfere with a natural signaling system throughout our brains, nerves and immune system.
Writing in the New Scientist, journalist Helen Phillips said that “results of clinical trials of cannabis have been mixed and it now seems there are fundamental problems with how our bodies respond to the stuff. Even with purified cannabis extracts, changing the amount, time or place of a dose could produce completely opposite effects on the body.”
Susanne Sorensen, M.D., of the U.K.’s Alzheimer’s Society welcomed further research in this area but added that “this is a fairly new field of research and producing 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.”
Marchalant Y. et al. Endocannabinoid agonist effects on inflammation and aging in rats. Presented Oct. 18, 2006 at the meeting of the Society for Neuroscience, Georgia World Congress Center, USA.
Eubanks L. M. et al. A Molecular Link between the Active Component of Marijuana and Alzheimer’s Disease Pathology. Molecular Pharmaceutics, published online August 9, 2006.
Ramirez B. G. et al. Prevention of Alzheimer’s disease pathology by cannabinoids: neuroprotection mediated by blockade of microglial activation. Journal of Neuroscience, Vol. 25, February 23, 2005, pp. 1904-13.
Phillips H. Medical cannabis is a blunt tool. New Scientist Magazine issue 2562, July 29, 2006.
Marijuana may block Alzheimer’s. BBC News, published online February 22, 2005.