This post is part of our High-tech High series, which explores weed innovations, and our cultural relationship with cannabis, as legalization in several U.S. states, Canada, and Uruguay moves the market further out of the shadows.
These days, there's a lot of potent weed to choose from. Take, for example, "Grandaddy Purple," "Matanuska Thunder Fuck," and "Gorilla Glue # 4," to name a few.
After the recent midterm elections, there are now 32 U.S. states where marijuana is legal for adults, recreationally, medically, or both. Increased legalization naturally opens up a larger market and incentives for businesses to grow finer, more competitive cannabis products. For better or worse, that often means marijuana strains with higher contents of THC -- the natural psychoactive chemical that binds to your brain and produces a high.
But how much THC, short for Tetrahydrocannabinol, can the human mind really handle? Is there a limit? Although there's still relatively scant scientific research about how marijuana affects the mind and body, scientists largely agree that how high you can get -- even from the most potent marijuana strains -- depends almost completely on an individual's weed habits.
"It’s really dependent on the history of use in that individual," Richard Miller, a professor of pharmacology at Northwestern University's Feinberg School of Medicine, said in an interview.
Our brain cells are covered in receptors, which can be thought of as docks or landing sites that chemicals like THC can bind to. Like turning a key to open a door, the binding of THC onto a receptor sets in motion a series of biological events that alters how you think and feel, creating a high.
But like anything used too much, these receptors can become overtaxed.
"They tend to work a little better or worse depending on how much they’re used," said Miller.
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For someone inhaling or consuming lots of cannabis, they're likely to desensitize their brain receptors and grow a tolerance to even today' s most potent cannabis.
"If you flood them [receptors] with lots and lots of cannabis there might be a tendency for them to work less well," said Miller.
"That's something we see with all drugs," he added. "It’s true with Aspirin, nicotine, LSD, cannabis and so on."
Still, Miller notes that scientists have much to learn about how high-potency marijuana, or concentrated THC devices like vape pens, affect us differently than other lower potency strains.
Cinnamon Bidwell, a neurobiologist at the University of Colorado Boulder's Institute of Cognitive Science, emphasizes that these products are simply too new.
"Most of our data are based on very low-potency, government-grown cannabis," Bidwell said, noting that cannabis is still federally illegal, and challenging to study. But even so, her lab has been able to begin studying how people are physiologically affected by extremely potent, concentrated cannabis products.
"Our data suggests that there’s a tolerance," she said.
In that case, "Matanuska Thunder Fuck" -- however potent -- will likely have a dramatic affect on the causal user, but a weaker affect on the everyday marijuana consumer with overtaxed receptors.
"It's more a question of the pattern of use," emphasized Miller.
Just how potent is today's weed, anyway?
There's little question that potent marijuana can be easily purchased today, in states where it's legal. (Though, there's evidence that popular or marketed strains have similar THC concentrations -- regardless of what producers advertise.) But today's potent weed is perhaps not quite as novel as some think.
Powerful pot has been around for a while.
"This narrative that there are much more potent strains of cannabis flower today is just not true," Peter Hendricks, an associate professor of health behavior at University of Alabama at Birmingham's School of Public Health, said in an interview. "There have always been very potent strains of cannabis on the market."
What's more, for centuries people globally have distilled hashish -- a high-concentrated THC resin -- from cannabis strains, Hendricks said.
What's changed, he said, is that there's not as much bad, or weak, weed around. "You're less likely to find stains with low-THC content, whereas you may have in the past."
Weed might generally be better, but the more significant advent -- and potential problem -- is the popularization of modern vaping devices that use highly-concentrated THC -- with levels approaching 100 percent THC content (for reference, 20 percent THC in a cannabis plant is considered quite potent).
"Now that could be somewhat problematic," noted Hendricks. "It could lead to use that is less mindful."
"One can simply insert a cartridge into a device and inhale," he added.
And this could lead to a robust marijuana tolerance, even to the most potent cannabis products.
"They [users] have to use a highly-concentrated product to just experience a subtle effect," said Hendricks.
For someone that has a low tolerance to THC, however, consuming too much cannabis or even low quantities of a highly-potent persuasion may experience a "green-out," Hendricks said, resulting in nausea, dizziness, some disorientation. But overall, "it's nowhere near as dangerous as alcohol or tobacco," he said.
It's also important to note that many new cannabis products are also often infused with other natural THC-related compounds, commonly called terpenes, that might influence the type of experience or high -- known as the "entourage effect." Cannabis producers often cite a 2011 study when they promote the medicinal, flavor, and psychoactive effects of terpenes, but there's a need for many more peer-reviewed studies -- which is research that is viewed critically and vetted by other scientists.
In its unaltered plant form, however, cannabis has likely been used by peoples of disparate cultures for thousands of years. Today's strains might generally be more potent, and this means being mindful of how you use it -- like any drug.
"Like any medicine, it has to be used properly," said Hendricks. "If we want to call this a medicine, it requires you being respectful of it."
