Scientists injected people with pure THC and gave them a series of tests to learn how marijuana affects basic motor functions.
What, you don’t normally consume cannabis intravenously? Moving on…
With a majority of states having passed laws legalizing marijuana in some form, there’s strong interest in determining how its components impact motor skills. To that end, researchers at Yale School of Medicine recruited 23 former cannabis consumers, administered low- and high-THC infusions and and had them perform several psychomotor tests.
The results, released online on Wednesday, are set to be published in the Journal of Psychopharmacology.
What the researchers found is generally consistent with earlier studies: the THC infusion “resulted in robust and significant deficits in motor performance” in a dose-dependent manner.
There was one test—where participants were asked to recognize a numeric sequence displayed on a screen and then press a response pad—that showed no significant difference in performance with or without THC. But when it comes to fine motor skills and response time, the study showed evidence that THC impaired the participants. The higher dose (0.03 mg/kg) led to poorer performance compared to the low dose (0.015 mg/kg).
The dosing was based on previous research into the blood plasma concentration of THC after smoking a standard joint. The higher dose is roughly equivalent to three-quarters of a joint and the lower dose is equivalent to one-quarter of a joint, according to the study.
Impairment from THC has been soundly established in earlier research. But what stood out to the researchers wasn’t that THC seemed to impair psychomotor skills; it was that participants who received the low and high dose THC reported feeling equally high.
“Perhaps even more concerning is the fact that even though the high dose of THC produced greater psychomotor deficits, subjects were not able to distinguish between levels of intoxication across the low- and high-dose conditions. This suggests that it may be difficult for individuals to gauge their level of psychomotor impairment based upon subjective feelings of intoxication, which could lead to greater risk during psychomotor-dependent behaviors.”
The subjective self-reports seemed to reinforce the idea that the “high” effects “plateau with increased doses of THC, while subjective alertness and postural sway continue to worsen.”
“Taken together, these data suggest that while several domains of motor function are disrupted by THC, subjective feelings of intoxication are dissociable from cannabinoid-induced psychomotor effects,” the researchers wrote.
There were a couple limitations to the study. First, it was designed to test how THC alone impacts motor function, whereas most consumers are exposed to numerous cannabinoids, including CBD, when they use marijuana. Second, the participants hadn’t used cannabis in at least the past three months, which means the effects were likely more pronounced than they would be in a frequent users whose developed a tolerance.
“These limitations notwithstanding, to our knowledge, this is the first controlled study examining a range of psychomotor functions in humans during the administration of several doses of IV THC,” the researchers wrote.
“These results suggest that THC exhibits robust effects on fine motor control and motor timing in a dose-dependent manner, which have implications for real world psychomotor-dependent behaviors such as driving, weapon use, operating machinery, work-related tasks, and skilled labor.”
(The researchers each reported potential conflicts of interest, including receiving grants from major pharmaceutical companies.)
Photo courtesy of Chris Wallis/Side Pocket Images.
Smoking Marijuana Actually Improves Working Memory, Study Indicates
A new study contains a finding that runs counter to common stereotypes about marijuana and forgetful stoners: smoking cannabis actually seems to improve working memory.
Researchers at the University of Florida acknowledged that their study, which involved rats and was published in the journal Neurobiology of Learning Memory, was unique. Much previous research has concluded that cannabis impairs cognitive performance. But the same time, many of those studies didn’t involve actually inhaling marijuana smoke like this one did.
The team put the 32 rats (split evenly by gender) through a pair of delayed response tasks that involved either finding and pressing a lever a certain amount of times or poking their nose into a feeding trough a certain amount of times—the reward being food pellets, of course. The first few times, the rats were sober; in subsequent experiments, they were exposed to cannabis smoke.
“Cannabis smoke improved working memory accuracy. Placebo smoke did not affect working memory accuracy.”
For male rats, the marijuana didn’t seem to have any effect at all, but for female rats “exposure to cannabis smoke significantly enhanced choice accuracy,” the researchers wrote. That said, baseline performances (prior to exposure) were lower in females compared to males, which “raises the possibility that the enhancing effects in females were due to their relatively worse baseline performance rather than to sex differences in the effects of cannabis per se.”
“The overwhelming majority of research in both animal models and human subjects shows that acute administration of cannabis and cannabinoids induces deficits in tests of cognitive function, including working memory. In contrast, the current experiments show that acute exposure to cannabis smoke enhanced working memory performance in a delayed response task in rats, particularly in females in which baseline levels of task performance were lower than those in males.”
Nearby Marijuana Shops Make Homes And Rentals More Valuable, Studies Show
When a shop selling marijuana opens (or closes), there’s a direct impact on housing and rental prices in the surrounding area, according to a pair of recent studies.
Housing prices for new homes increase by 7.7 percent on average if they’re located within a quarter mile of a new dispensary.
A study published in the journal Contemporary Economic Policy evaluated how the price of new homes in Denver, Colorado, changes when a cannabis dispensary opens up nearby. Researchers compared the prices of homes before and after a dispensary opened within .25 miles, .25-.5 miles and .5-.75 miles.
When new dispensaries opened within .25 miles, housing prices jumped 7.7 percent on average. There was still a 4.7 percent increase for homes located within .5 miles, but the effect “disappears entirely” for houses that are further than .5 miles from a new dispensary. The researchers also found that the effect was slightly more pronounced if the dispensary was the first to the area.
“Our results suggest that despite potential costs, legalization is capitalized as a net benefit in housing prices,” the researchers wrote.
Interestingly, new dispensaries seem to have about the same impact on housing prices as new grocery stores, the study found. But the “mechanisms through which grocery stores affect housing prices are more obvious than dispensaries.”
“If public sentiment surrounding marijuana is positive, homebuyers may also prefer to select into neighborhoods with more dispensaries for convenience. Ultimately however, our data do not allow us to directly determine the underlying mechanisms driving this result, so these potential explanations should be considered speculative.”
Losing a marijuana coffeeshop causes a three percent decrease in Airbnb rental prices.
Amsterdam’s famous cannabis coffeeshops are known tourist attractions, but what happens when one shuts down? For his master’s dissertation, doctoral student Igor Goncalves Koehne de Castro identified at least one collateral effect: Rental costs on Airbnb drop by about three percent on average if the closure was within 250 meters of the lodging.
If the coffeeshop was further than 250 meters, rental prices didn’t change significantly.
There were plenty of examples for de Castro to study, which spanned from 2014 to 2017, because several coffeeshops have closed in response to new laws in recent years, including one in Amsterdam that prohibits the shops from operating within 250 meters of a school.
After controlling for other possible factors, de Castro developed a series of models based on Airbnb data on rental prices over time and their proximity to recently closed coffeeshops. The study revealed that these shops “present a positive impact” on rental prices for lodgings close to the shops—presumably because people who rent through Airbnb are “tourists” who are “sensitive to distances.”
“The findings of this study suggest that, for the city of Amsterdam, the de facto legalization of cannabis actually has a positive externality,” de Castro wrote. “This result puts new evidence to the debate of drug laws and policies, a matter that still lacks data and research.”
Photo courtesy of WeedPornDaily.
Vaporized Marijuana Produces A Stronger High Than Smoking It, Study Finds
Vaping marijuana gets you higher than smoking it, according to a new study published in an American Medical Association journal.
To test the difference, researchers started by recruiting 17 people who’d consumed cannabis in the past year but had abstained for at least the last month. Each individual participated in six sessions that lasted eight and a half hours—three where they smoked marijuana and three where they vaped it. There were three THC concentrations for both rounds of testing: 0mg, 10mg and 25mg.
After smoking or vaping, the participants were asked to fill out questionnaires to self-report their experience and then the researchers administered a series of physical and cognitive tests. Their blood was also subsequently analyzed.
The most obvious result was that when people smoked or vaped the 0mg control substance, it didn’t have a physical or psychological effect. But at 10mg—and especially 25mg—the participants got pretty stoned. They reported feeling hungry, sleepy and pleasant. Their mouths were dry. Some became anxious or paranoid. Three participants experienced adverse events like vomiting after consuming the 25mg cannabis.
Most regular consumers can probably attest to experiencing at least some of these things from time to time. But what might come as a surprise is that vaporized cannabis “produced significantly greater subjective drug effects, cognitive and psychomotor impairment, and higher blood THC concentrations than the same doses of smoked cannabis,” the study authors wrote in the paper published by JAMA Network Open on Friday.
In previous studies, researchers allowed participants to adjust their THC dose, which is likely why earlier results suggested that smoking got people higher than vaping. But when you hold the THC dose constant, vaping seems to be a more efficient delivery system, probably because smoking requires combustion that can deplete THC.
“Vendors and consumers of cannabis products should be aware that inhaling cannabis with a vaporizer could produce more pronounced drug effects and impairment than traditional smoking methods.”
That’s relevant information as the marijuana market continues to expand. More people are opting for vaporizers, and the study indicates that infrequent or new cannabis consumers should probably approach vaporizers with a bit more caution, start low and go slow.