In the 1980s, drug-war propaganda compared cannabis-addled brains to fried eggs. We have since learned that eggs are nature’s perfect food. Cannabis has gone through a similar health upgrade, in part because of the work of people like Linda Parker, Ph.D., research chair in behavioral neuroscience at the University of Guelph, in Canada. She’s the author of Cannabinoids and the Brain, so we listened closely as she discussed gray matter under the influence of a famous green plant.
Her introductory point: The brain is loaded with CB1 nerve receptors, which are affected by the body’s own supply of cannabinoids. So if you smoke, vape, or swallow the 100-odd cannabinoids from marijuana, the effects can be profound. Modestly, she points out that we’re still learning about those impacts. But we can say: The brain effects we already know about are significant, and will gain added By Peter Moore relevance as Parker and countless others move the research forward. For now, here’s what we know about how cannabis impacts key brain structures, for better and worse.
What it does: Regulates emotions, including anxiety and depression. Your amygdala on cannabis: The amygdala is “bi-phasic,” says Dr. Parker. That means that while low doses of THC can decrease anxiety, high doses can increase it, inducing pot paranoia. “Cannabis in the 1960s and 1970s included more CBD, which has a moderating effect on THC and reduces paranoia. That’s different from much of the cannabis that is used today, which tends to have high-potency THC and not much CBD.” More balanced strains are a better option if you’re anxious about being anxious.
What it does: Consolidates learning and memory. Your hippocampus on cannabis: The inhibition of short-term memory—”What did you just say, dude?”—is one famous effect, but that isn’t all bad: If you come home from a rough day at the office, reaching for a weedy memoryeraser may be just the thing. And speaking of the office, rat studies show that CBD can help the mind bounce back after stressful events.
The Cerebral Cortex
What it does: Governs cognition, decision making, nausea, and emotion. Your cerebral cortex on cannabis: In the face of the AIDs epidemic, and increasingly toxic treatments for cancer, we learned that cannabis could lessen nausea, thereby stimulating appetite and helping sick people build weight and strength. Dr. Parker also notes that cannabis can impair decision making. But if you decide to go for a drive under the influence—don’t!— you will at least drive poorly, slowly. Alcohol has the opposite effect.
What it does: Regulates hormones and eating behaviors, and plays a role in anxiety and depression. Your hypothalamus on cannabis: The munchies happen when THC barges in on a hypothalamic process that suppresses hunger, and turns it into one that encourages gorging. Back slowly away from the stuffed-crust pizza. On the positive side, you may stress-eat less when CBD hits your hypothalamus. That calming cannabinoid helps compensate for plunging levels of anandamide (the “bliss” molecule) when you’re under pressure, and helps return your system to homeostasis— a state of balance.
What it does: Motor control, bodily coordination. May also play a role in addiction. Your cerebellum on cannabis: This brain region is packed with CB1 receptors, so it’s a cannabinoid playground—albeit one without much playing. One study noted, with hilarious deadpan, the tendency of cannabis to bring all activity to a halt. Sometimes couchlock is a good thing. And after decades of research into cannabis as a “gateway drug” (now discounted), there is evidence it may be an exit strategy from addiction as well, in part because of its relation to…
The Brain Stem
What it does: Regulates the autonomic nervous system, with such vital functions as heart rate and breathing. Your brain stem on cannabis: Parker points out that there are very few CB1 receptors in the brainstem, which is why there is no lethal effect of cannabis, even at high doses. No matter how much you ingest (careful now), you’ll only feel uncomfortable, not cease breathing. Which is already a major advantage over heroin, cocaine, opioids—even alcohol. It’s one reason cannabis is being considered as a safer option when bringing people down off of addictions.