For 50 years, cannabis research was largely closed off to scientists because of federal regulations that created massive hurdles for anyone hoping to look into the plant. Up until 2020, researchers in the United States could only study cannabis plants grown by the University of Mississippi in conjunction with the National Institute on Drug Abuse. Finally, in 2021, the U.S. Drug Enforcement Administration allowed more organizations to start growing different varieties of cannabis for medical and scientific research purposes.  As a result of the more lenient rules when it comes to research, there have been amazing new developments in what scientists can say definitively about cannabis.

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Sickle Cell Disease

The Center for the Study of Cannabis at the University of California Irvine recently looked into whether patients who smoked weed would feel less pain due to Sickle Cell Disease. That genetic disease affects about 100,000 Americans, afflicting them with chronic pain that’s normally treated with opioids. Those addictive drugs have to be taken for long periods of time at high doses, so it would be beneficial to find another option. The study had a small sample size, but found there were no adverse side effects from the cannabis and that marijuana helped boost their mood.  “Better understanding how cannabis can and cannot effectively treat pain may help curb the ongoing opioid epidemic and may aid in safely managing chronic pain,” the researchers said


Alzheimer’s and dementia are horrible diseases that gradually take away cognitive function and eventually lead to death. UCI’s Center for the Study of Cannabis also looked into how CBD and THC could be used as a treatment for those diseases alongside other pharmaceuticals.

A senior with Alzheimer's is comforted by a doctor Source: Shutterstock
After analyzing nine peer-reviewed studies, the researchers found CBD can protect certain neurons, promoting neuronal cell growth in the hippocampus, the part of the brain that deals with motivation, emotion, learning, and memory. Moreover, they found CBD used in conjunction with THC was more effective than THC alone. 

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How Demographics Affect Purchasing Habits

 A health economist aiming for her PhD spent four and a half years studying medical marijuana patients in New York State for her dissertation. She hoped to find something that could help both legislators and healthcare workers understand more about marijuana purchasing patterns across demographics.  The PhD candidate, Alexandra Kritikos, found never before quantified links in the buying patterns of different age groups, genders, and in people who buy weed for different purposes like physical versus mental issues.  Kritikos also found something the National Institute on Drug Abuse had called a top research priority: the average dose of THC. She saw average THC concentration in cannabis grown in North America has increased from 4% in 1995 to 12% in 2014. CBD concentration decreased in the same timeframe. The market shift she studied showed there’s now higher demand for cannabis with a greater content of THC, with most people opting for flower with 20% THC or extracts with 70%.  Her findings are already informing policy decisions in Massachusetts. 

Cannabis Tolerance

Similarly to alcohol, some people have higher tolerance than others when it comes to THC. There are plenty of things that affect that, like weight, metabolism, eating habits, muscle mass, and gender; new research shows differences in the brain’s reward circuitry have an impact too. Studies into those neurometabolic variations have given scientists a clue as to why people who use cannabis more often eventually have to use more to feel the same effects.  The tolerance doesn’t just affect how high people feel, however; it also impacts how much people experience the impairing and potentially negative effects of the substance.  A study published in Addiction Biology tried out a double-blind, randomized assessment of twelve people who used cannabis occasionally and twelve who were frequent users.

A cannabis bud under a microscope Source: Shutterstock
Each person was either given extremely high doses of THC or a placebo, then had their brains examined in ultrahigh field MRIs to study chemical metabolisms. They also underwent magnetic resonance spectroscopy to analyze molecules in the brain.  The researchers found that occasional cannabis users who were given such a large dose of THC had major neurometabolic changes. Their functional connectivity decreased, and striatal glutamate levels (which are associated with psychosis) increased. That led to difficulty concentrating. Those changes were entirely absent in chronic marijuana users who were given the same dose.  “The finding that cannabis altered circuitry and distorted behavior in occasional, but not chronic users, suggests reduced responsiveness of the reward circuitry to cannabis intoxication in chronic users,” the researchers concluded. 

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Companies are also doing more research into the effects of individual isolated cannabinoids. There are around 150 cannabinoids within the cannabis plant, and each affects the human body differently, giving them varying capacities to impact and target certain health issues. CBD is an example of that: a close relative of THC, but one that affects the human body in a completely different way.  As Wikileaf has reported in the past, companies have started exploring CBG and CBN, Delta-8 and Delta-10, as well as THCP, a more potent version of THC.  As more research goes into the identification and isolation of new cannabinoids, the market for what we think of as cannabis to expand wildly. 


Not all research is being done in the U.S. The British Journal of Pharmacology recently published a study from the University of Sydney looking into the use of cannabis extracts to treat epilepsy. That’s thanks to an enormous donation to that University made in 2015 by a family that hoped to advance scientific research into cannabinoids as therapeutics.

Charlotte Figi, famous for treating her Dravet Syndrome with CBD Source: @charlotteswebcbd
The researchers discovered CBDA, a particular isolate, is better at reducing certain seizures than CBD. They found that isolate could make an enormous difference in the treatment of Dravet Syndrome, a type of epilepsy that sets in before a child reaches its first birthday and afflicts them for the rest of their lives. So far, it’s been resistant to drug treatment. However, that isolate can make seizures more likely in other types of epilepsy.  And although cannabinoids can be isolated, some researchers believe they work best when all are present and the full spectrum of the cannabis plant is used for medicine. 

Why This Matters

The more researchers know about cannabis, the more thoroughly they’ll be able to prove whether it is truly safe, and whether it can be used to adequately treat certain medical conditions in a way the government can approve of. Many pharmaceuticals have harmful side effects or can be addictive and lead to use of other drugs. If marijuana could be used as a substitute, it could have tremendous impacts in the mental and physical health of countless people. President Joe Biden has said he’ll only consider legalization of marijuana at the federal level after more research is done on it. The President has expressed concerns in the past that cannabis could be a “gateway drug” and he wants that disproved by researchers. As mentioned, research has been difficult thus far because of the very regulations keeping marijuana outlawed federally. The more studies are done however, the closer the United States gets to accepting marijuana.