Cannabis Study: How THC Affects Learning and Memory at Different Ages

A 2017 study about the impact of THC on memory in young vs. older mice

 “All diseases run into one, old age.” –Ralph Waldo Emerson“Memory Loss From Old Age Could Be Reversed By Smoking Marijuana” has been an interesting and attractive headline of a recent study in mice.[1] It’s obviously an alluring idea, particularly given the toll cognitive decline receives when you become older; rather than making you dazed and confused, THC would really help you restore cognitive function in your old age.[2] The studies made fascinating remarks regarding how THC affects learning and memory at different ages of young vs. older mice. But the studies didn’t engage smoking or cannabis consumption. The studies include these 3 basic things:Younger mice possess stronger learning and memory capabilities than older mice Giving young mice THC normally makes them perform worse on learning and memory tests The endocannabinoid system influences the development of ageing in the brain, and endocannabinoid levels in the brain decline with age.Dr. Andras Bilkei-Gorzo, the lead of the four researchers of the study, commented on their experiments, “We had learned from previous work that decreased cannabinoid signaling accelerates brain ageing. We asked whether enhancing cannabinoid system activity might slow down—or even reverse—normal cognitive decline that comes with ageing.”  This clear-cut idea may make you interested to know how their experiments worked.

THC, Memory, and Aging Study: Basic Findings and Summary

The young and the older mice were grouped separately and some were given a constant daily dose of THC for 28 days, while others were served as controls (without THC). After 28 days, the THC treatment was stopped and their learning and memory abilities were judged. It was observed that the old mice did better on learning and memory tests while getting a 28-day THC treatment beforehand compared to the young mice without a THC treatment. It was also observed that the molecular changes occurred in a brain area called the hippocampus which paralleled these behavioral changes. Notice the Experiment 1 that describes how it happened. Experiment 1: Chronic THC exposure in old mice can increase the number of connections between neurons in the brain. Brain cells often have structures called “spines.” Each spine marks a single connection between two brain cells. Compared to young mice (left), neurons in old-mice (middle) tend to have fewer spines. After chronic THC exposure (right), the brain cells of old mice often look more like those of young mice–they have more spines, and therefore more connections to other brain cells. With our age, our endocannabinoid system changes, including changes in CB1 receptor levels. Notice the Experiment 2. Experiment 2: CB1 receptor levels decrease with age, and chronic THC exposure may compensate for this in old mice. Compared to young mice (top-left), old mice tend to have fewer CB1 receptors in their brain (top-right). Because THC activates CB1 receptors, chronic exposure to low-dose THC may compensate for this age-related change in the endocannabinoid system. Each red “V” represents a CB1 receptor. At any given time, some CB1 receptors may be activated (yellow lines) by cannabinoids, while others are not. The most important receiving from this study is that plant cannabinoids like THC might have quite different effects on people because of the age-related changes in the endocannabinoid system. And uplifting cannabinoid levels could help compensate for some of the age-related changes.

Study Caveat: Mice and Humans Metabolize Compounds Differently

A study titled “A chronic low dose of THC restores cognitive function in old mice” was done in which mice were given 3 milligrams per kilogram (mg/kg) of body weight of THC daily for 28 successive days prior to learning and memory assessments. The amount would be equivalent to nearly 204 mg of THC for a 150-pound person. About 8.5 mg of THC was spread equally every hour throughout the day. About this low dose, Dr. Bilkei-Gorzo explained, “Humans are much more sensitive to psychoactive substances than rodents. The effective dose of anti-anxiety and anti-depression drugs is roughly 100 times higher in rodents compared to human patients. The same is true for THC—one needs a higher dose in rodents to see effects comparable to humans.” We need to be cautious about translating animal studies to humans because mice and humans metabolize plant cannabinoids, pharmaceuticals, and other elements at different rates, and sometimes in very different ways. There is another reason to be careful about the impact of cannabis consumption for learning and memory in older humans. As mice were unable to inhale smoke or consume cannabis products like normal human beings, they were given THC through small devices surgically implanted under their skin to be directly administered at a constant rate.[/vc_column_text][vc_custom_heading text=”The Future of Medical Cannabis Research: Which Countries Will Lead the Way?”

The Future of Medical Cannabis Research: Which Countries Will Lead the Way?

]In spite of the above caveats, the study demonstrates fascinating results and also shows different effects of cannabinoids like THC on a person’s age. These are because of age-related changes in the endocannabinoid system unfolding naturally over time. Now, one of the important matters is whether similar results would be seen in a human clinical trial, and these results would be seen after consumption of cannabis products, or older people would need to acquire pure THC. Happily, the same researchers are designing experiments to investigate the effects of THC on elderly people having mild cognitive impairment. Dr. Bilkei-Gorzo assures saying they are starting the clinical trial at the end of 2017 or beginning of 2018. It is also noted that there are clear differences between cannabis and pure THC. Cannabis has the benefit of being better tolerated by patients, whereas pure THC can be precisely dosed. The researchers at the University of Bonn, in Germany, in collaboration with scientists at Hebrew University in Israel led this recent study. With the prospect of major budget cuts, the United States moves slowly in medical cannabis research, whereas countries like Israel, Germany, and Canada may set themselves as the world’s medical cannabis research leaders, and be the pioneer to harvest the benefits.