Medicinal Aging?

Compounds similar to THC, the psychoactive ingredient in marijuana, have been shown to reduce memory impairments in the aging brain. While marijuana is widely known to impair memory in the short-term, leading scientists from Ohio State University are contradicting this age-old dogma by investigating how endocannabinoids, the brain’s naturally occurring cannabis, can improve memory function in the long-term.

Emerging evidence, presented this week by OSU's Dr. Gary Wenk and his colleagues at the Society for Neuroscience meeting in Washington D.C., indicates that the development of a legally prescribed drug similar to THC could slow or even prevent the onset of Alzheimer’s disease.

Memory loss is a key feature of Alzhiemer’s disease, which affects brain areas critical for emotional processing and memory formation. Inflammation in these areas is thought to contribute to the memory loss seen in Alzhiemer’s disease and even in normal aging. The THC-like drug used by Dr. Wenk, WIN-55212-2 (WIN), has been shown previously to have anti-inflammatory effects in both young and old rats. More recently, this same drug has aided in neurogenesis, or the growth of new brain cells in a dish- a finding that suggests such a drug could help grow brand new cells in an actual aging brain. If these newly formed cells could then link up with existing neural networks, new memories could potentially be made. At least this is the hope.

Right now this research is done on rats, as WIN is not used in humans due to its psychoactive effects. Aged rats normally perform poorly in a memory task where visual cues are used to remind the rats where a hidden platform lies in a pool of water. Aged rats receiving non-psychoactive doses of WIN perform substantially better in this task. Additionally, the specific receptors that WIN targets have now been identified in the hippocampus, an area critical for new memory formation. WIN’s action on these receptors decreased inflammation in the hippocampus, an effect that could potentially contribute to the amelioration of memory loss in aged rats.

While such drugs are not yet legally available in the U.S., is it advisable for the millions of people with a family history of Alzhiemer’s to eagerly await the legalization of medicinal marijuana nationwide? The short answer is, no. “The end goal is not to recommend the use of THC in humans to reduce Alzheimer’s,” Dr. Yannick Marchalant, a member of Wenk’s team, advises. “We need to find exactly which receptors are most crucial, and ideally lead to the development of drugs that specifically activate those receptors. We hope a compound can be found that can target both inflammation and neurogenesis, which would be the most efficient way to produce the best effects.”

Photo source: The program for the 2nd International Cannabis and Mental Health Conference