I was an avid marijuana smoker for nearly ten years of my youth, and today I am a neuroscientist who studies addiction. I loved the taste, the smell, and the fabulous buffering effects of weed separating me from the messy business of interacting with other people and fulfilling my daily obligations-as well as the promise of something new and glittering in the midst of the relatively unappealing present. As an antidote to boredom, the drug made everything more interesting, and time and space delightful instead of threatening.
Not to belabor the point, but from the first time I got high until long after I’d smoked my last bowl, I loved the drug like a best friend. Some people it makes sleepy, others paranoid (due, no doubt, to an unfortunate confluence of neurobiology and genetics), but for me it was nearly perfect. One of my favorite moments was shortly after coming to consciousness in a new day and seeing for an instant the vast bleakness of life before me and then suddenly realizing-just as newlyweds might reach in excitement and hope for a spouse beside them in the bed-that I could get high. The first few hits of the day were reliably comforting as the gray dust of reality was blown away to reveal beauty and meaning in everyday encounters.
If alcohol is a pharmacological sledgehammer and cocaine a laser (and they are), marijuana is a bucket of red paint. This is so for at least two reasons. First is its well-known ability to accentuate environmental stimuli: Music is amazing, food delicious, jokes hilarious, colors rich, and so on. Second, its effects are widespread. It’s a five-gallon bucket and a four-inch brush, painting up the grain on all kinds of neural processing. Unlike cocaine, for instance, which acts in relatively few discrete spots in the brain, THC, the active ingredient in marijuana, acts throughout the brain, and in some regions in every single connection (of which there are trillions).
The broad reach of this drug was a big surprise to researchers when it was realized in the early 1990s. I was in graduate school at the time, and the news was so momentous that-in the way that some people remember where they were and what they were doing when Kennedy was shot or the Twin Towers came down-I remember exactly where I was when the THC receptor was identified all over the brain.
Of course, we didn’t evolve the machinery to produce these complicated receptor proteins or spend the energy to put them all over the brain just in case someone offers us a hit. The wide and dense distribution of cannabinoid receptors has profound implications. In a nutshell, the chemicals-endocannabinoids-that trigger these receptors act as a sort of exclamation point on neural communication, indicating that whatever the message just transmitted across the synapse, it was important.
The purpose of the cannabinoid system is to help to sort our experiences, indicating which are the most meaningful or salient. The system activates naturally to distinguish input that might contribute to our flourishing-for instance, a good source of food, a potential mate, or other meaningful connections, information, or stimuli. Natural cannabinoids and their receptors are all over the brain because such input might be carried in any number of pathways, depending on the exact nature of the stimulus.
For example, let’s say one day you are exploring your surroundings somewhat aimlessly, when you serendipitously begin following a route that eventually leads to something good. The millions of neurons involved in this discovery-including those involved in processing input from your senses, stimulating movement, coding memories, or thoughts connecting this good thing to your plans or communicating it to others-are likely all releasing cannabinoids to turn up the volume on this information, helping to distinguish it from the other parts of your day in which interactions with the environment weren’t all that special.
This should make it easy to understand why the stimuli we encounter when stoned are so intensely rich. Unfortunately, there is a dark side to all this neural spotlighting. If everything is highlighted as meaningful, then nothing can really stand out. What use is a watering can, after all, if the fields are flooded? After one comes down, the lack of sorting makes it hard to recall what was so wonderfully urgent about those experiences.
Also unfortunate is that chronic exposure leads to substantial consequences. The brain adapts by downregulating the cannabinoid system so that without copious amounts of pot onboard, everything becomes dull and uninspiring. There’s been a long-standing debate, akin to one about the relationship between cancer and smoking, about whether regular marijuana smoking leads to an amotivational syndrome (“amotivational” means lacking motivation). Does regular use lead to spending long hours on the couch watching cartoons, or does it just so happen that people who like to sit around watching mindless television also enjoy marijuana?
Cigarette companies argued for decades that a predisposition for cancer and the tendency to inhale cigarette smoke just coincidentally occur in the same people. In both cases, common sense and mounting evidence point to the same thing. Downregulation of cannabinoid receptors makes the user more suitable for jobs that don’t require creativity or innovation, exactly the effects that initial exposure seemed to stimulate.
After I got sober, it took me a little over a year to go a single day without wishing for a drink, but it was more than nine years before my craving to get high abated. For the longest time, I couldn’t go to indoor concerts, especially if I was in proximity to pot. Good sinsemilla would induce a sort of mini panic attack. During this nearly decade-long purgatory, I broke up with a pretty good guy (great cook, decent skier) only because he occasionally wanted to get high. Though it was not even around me, I was unable to bear the idea that he’d be somewhere laughing his ass off, while I’d be totally straight, missing the joke.
My first few months without pot were especially miserable. Though I was in a new environment, with new friends and countless novel experiences, I experienced everything as bland beyond belief. However, about three months into my new drug-free life, I was walking along a street in Minneapolis and nearly fell to my knees, struck by the brilliance of the fall foliage. All around me were a million bright oranges, reds, yellows, and greens; I must have felt the way the first viewers of movies in Technicolor did. Where had all this come from? In fact, downregulation had reversed with my abstinence. As my receptors returned, so did my appreciation for everyday beauty.
The takeaway is this: downregulation has consequences. I have a friend and colleague, a smart professor at a good university, and a family man, who used to like to drink a lot but was finding some of the effects embarrassing if not disabling. He switched to smoking pot. He started to notice that if he smoked a little before doing his “daddy duties” he was, as he described it, a more engaged parent. With just a couple of hits, he was able to play more with his children and didn’t find the carpool, meal preparation, or team coaching quite so irritating and tedious.
“Great,” I said. “How’s it with your kids when you’re not high?”
“Increasingly irritating and tedious,” he admitted.
So, if you smoke weed, remember that infrequent and intermittent use is the only way to prevent downregulation and its unfortunate effects: tolerance, dependence, and a loss of interest in the unenhanced world.
From the book NEVER ENOUGH: The Neuroscience and Experience of Addiction by Judith Grisel. Copyright © 2019 by Judith Grisel. To be published by Doubleday, an imprint of the Knopf Doubleday Publishing Group, a division of Penguin Random House LLC.
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