Scientists Unravel the Weed Amnesia Mystery


It’s no secret that marijuana impairs working memory, a fact that’s fueled stoner stereotypes and posed a conundrum for researchers who want marijuana to be therapeutic but not forgetfulness-inducing. This adverse effect has hindered cannabinoid byproducts from reaching their medicinal potential. It doesn’t help there’s a lack of understanding of how cannabis affects memory.

However, research published Thursday in Nature is poised to be the first step in understanding how to toke up without your memories zoning out. In the paper, researchers explain that the “amnesia” caused by cannabinoids happens because of the activation of CB1 cannabinoid receptors. These are located in the mitochondria of cells in the hippocampus, which is the part of the brain involved in memory formation.

The researchers found that when they genetically eliminated the CB1 receptors from the mitochondria in mouse hippocampal cells, then they could prevent post-cannabis memory loss.

When a person smokes up, cannabinoids — the molecular compounds in cannabis responsible for its psychoactive effects — bind to the brain’s cannabinoid receptors. There are two variants of these receptors: CB1 in the brain, and CB2 in the body. This research, a result of a 28-person, six-year team effort, showed that the CB1 receptors in mitochondria regulate memory formation by regulating how mitochondrial energy is metabolized. When mitochondria malfunction — by, say, an incoming cannabinoid — memory processing gets disrupted. When the CB1 receptor is removed, the ability to form memories at a natural pace remains.

Removing the CB1 receptor of humans who smoke weed isn’t an option, so figuring out how to block them is likely to be the next step in this research. With the smoker population likely to increase after the recent legalization of the drug in four more states and a continued interest in making it better for people who want to use is therapeutically, it’s an especially important area of research to pursue.

By selectively disrupting the function of specific CB1 cannabinoid receptors, lead author Pedro Grandes explained in a statement, researchers could eventually develop “new therapeutic tools based on the most effective and safest cannabinoids in the treatment of certain brain diseases.”

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