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Taking a Science-informed Approach to Medical Marijuana

April 28, 2015

Originally appeared in in Alcoholism and Drug Abuse Weekly, April 27, 2015.
Photo of marijuana spilling from a prescription bottle

Opinion on marijuana has changed dramatically in the United States. The public increasingly perceives it as a benign substance, and there is growing interest in its potential medicinal uses. Already almost half of the states have medical marijuana laws, and congressional bills have recently been proposed that would reschedule the drug to reduce hindrances to research and facilitate marijuana’s use as medicine.

Advocates tout marijuana as a miracle drug with a wide range of potential therapeutic uses, while public health voices raise alarms about its dangers if made more widely available. The science justifying either position is often not as robust or clear as its partisans would wish. Marijuana’s impact on lung cancer remains unclear, for instance, but so does its actual range of medicinal benefits. The urgent need for more research is something all sides in the current marijuana debate can agree on. Policy changes around marijuana will need to be informed, as much as possible, by science.

There is solid evidence that the main psychoactive ingredient in marijuana, THC, is effective at controlling nausea and boosting appetite. There is also some preliminary evidence that THC or related cannabinoid compounds such as cannabidiol (CBD) may also have uses in treating autoimmune diseases, inflammation, pain, seizures and psychiatric disorders, including substance use disorders. Despite claims of marijuana’s usefulness in treating post-traumatic stress disorder, supporting data is minimal, and studies have not investigated whether symptoms may worsen after treatment is discontinued.

We do not yet know all the ways chronic treatment with marijuana or marijuana-derived compounds could affect people who are rendered vulnerable either by their illnesses or by their age. We also don’t know how medical marijuana laws will affect other aspects of public health and safety. For example, wider medical marijuana use could potentially impact driver safety, as both laboratory and epidemiological research link recent marijuana use to increased accident risk, likely reflecting marijuana’s disruptive effects on motor coordination and time perception.

Impact on teenagers

Perhaps the biggest public health concern around medical marijuana liberalization and legalization concerns the potential impact on teenagers, who could have greater access to it as a drug of abuse and who may increasingly see marijuana as a “safe, natural” medicine rather than a harmful intoxicant. Although there is still much to learn about marijuana’s impact on the developing brain, the existing science paints a picture of lasting adverse consequences when the drug is used heavily prior to the completion of brain maturation in young adulthood. In teens, marijuana appears to impair cognitive development, may lower IQ and may precipitate psychosis in individuals with a genetic vulnerability.

Most states currently don’t allow medical marijuana for children, but they too are vulnerable. Accidental ingestion of marijuana edibles by children has increased in Colorado since marijuana was decriminalized for medicinal use in 2009. Also potentially concerning is the possibility of increased prenatal exposure if women self-treat with marijuana to control nausea associated with pregnancy. Research suggests prenatal exposure could have adverse consequences for children’s future health and brain development. There is as yet no research on the potential effects of secondhand marijuana smoke on children growing up in households where parents smoke.

Even in conditions for which THC, CBD or other cannabinoid constituents of the marijuana plant prove to be medically beneficial, consumption of the marijuana plant itself or its crude extracts via smoking, vaporizing or eating is unlikely to be the most effective, reliable or safe way for patients to obtain these benefits. Laboratory research is ongoing to better understand how cannabinoids work in the brain and body and hopefully guide development of safe, reliable therapeutic compounds that have a minimum of adverse side effects.

Existing medications

Two THC-based medications, dronabinol and nabilone, are already approved by the Food and Drug Administration to treat nausea caused by chemotherapy and to boost appetite in patients with AIDS wasting syndrome. The United Kingdom, Canada and several European countries have approved a drug called nabiximols (Sativex), containing THC and CBD, as a medication for spasticity caused by multiple sclerosis (MS) and, in Canada, for MS- and cancer-related pain. Despite its success in reducing pain and spasticity, it has not received approval in the United States, and recent evidence has found impairments in cognition in users.

CBD on its own is not psychoactive and it actually mitigates the “high” produced by THC; it has been studied as a potential antipsychotic drug, and ongoing trials are testing its efficacy as an antiseizure agent. Some parents of children with severe forms of pediatric epilepsy have claimed that high-CBD (and low-THC) marijuana extracts control their children’s seizures better than existing medicines. The maker of Sativex has recently created a CBD-based drug called Epidiolex to treat children with these conditions, and is in the process of conducting initial small-scale trials. Evidence so far shows that CBD is only effective in controlling seizures in a small subset of patients.

As public approval for medical marijuana grows, we need to ensure that our policy decisions are science-based and not swayed by the enthusiastic claims made widely in the media or on the Internet. We need to support and encourage increased research on marijuana’s potential benefits and conduct intensified research on the cannabinoid system to inform the development of safe, FDA-approvable drugs. But the existing science on marijuana’s adverse effects on youth demands we also proceed with caution in making policy changes that could result in increased use of or exposure to marijuana by young people.

Also see related Drugs & Health blog post on Medical Marijuana from our Teens site

This page was last updated April 2015


Research roadblocks

In February, NIDA director Nora Volkow said that she is working to "reduce the barriers to research on marijuana." Could you clarify what she was referring to, and also if NIDA supports lifting the additional Public Health Service review that marijuana research -- and studies on no other drug -- needs to go through?

NIDA is supporting increased

NIDA is supporting increased research on marijuana in part by expanding the variety of marijuana available for research, including strains that contain high levels of CBD. For more information, please see: http://www.drugabuse.gov/drugs-abuse/marijuana/nidas-role-in-providing-marijuana-research


The Government has had every opportunity to study marijuana and its effects over the past hundred years or more. The claim that "we need more science" is bull. I am 58 years old, and they've been saying that since I was born. I've smoked cannabis 5 or more times a day for the past 40+ years, and I don't have a problem. Get over it! If it was harmful, the Govt. would have licensed and made money from it by selling to us all this time.

Truth, science, and marajuana laws.

The Federal laws state blatently untrue things to justify marajuana prohibitions. Those laws have prevented scientific research for decades. We are ignorant but so sure we are right that we outlaw scientific search for truth. Then we wonder why youth distrust government.

Waiting for Godot.

With full understanding that correlation is not causation, there seems to be an astonishing correlation with prior drug abuse, specifically marijuana (or hashish) and violent, senseless crime all around the world that I think should not be ignored. I suspect abuse months or years prior has drastically altered the brains in many of society's sociopaths.

All the Islamic terror groups, for instance, utilize plentiful drugs and narcotics during radicalization and during acts of terrorism. Evidence suggests the vicious drug cartels of Mexico use the drugs they market. The domestic drug gangs are known to use the drugs they deal, as revealed by testing during their arrests for violent crimes. Domestically, nearly all if not all our mass murderers and serial killers in recent decades used drugs. The same applies to nearly all our assassins or would-be assassins, many of the school and mall shooters, and many of the domestic acts of terrorism where public places were bombed.

And, virtually any homicide in the news today has a connection to drug abuse. A football star on trial for alleged murder is said to be a "chain-smoker" of marijuana, a Utah woman who killed all her babies used marijuana and meth, a cop shooter in NYC upset about 'police brutality' has a history of marijuana abuse, kills two cops, then himself. The list goes on and on, myriads of them. Police, judges, or anybody who reads the news diligently, can attest that the vast majority of these murderers are abusing or have abused drugs. And most alarming is that the so-called harmless drug, marijuana, seems to be the one substance abused by nearly ALL of the sociopaths.

Regardless of one's viewpoint, I imagine most would readily agree that marijuana does not necessarily render all abusers peaceful and non-violent!

Cannabinoid toxins of marijuana are known to affect the very part of the brain that harbors our basic feelings such as hunger, empathy for life and inhibition. One could imagine that perhaps some serious abusers are damaging that area's gray matter and depleting their minds of empathy for life and inhibition, thus enabling them to become remorseless killers.

Is anybody in high places, other than a few police chiefs around the country, connecting the dots? Why isn't anyone in the mainstream media, scientists, politicos, academics, talk show hosts, etc., at least wondering out loud if marijuana is enabling some abusers to become homicidal? Where are our open and inquisitive minds? Mum seems to be the word while many of the state's governors gleefully encourage marijuana legalization.

Is anybody out there haunted by the possibility that the marijuana used by the Boston Marathon bombers, the Oklahoma City bombers, the Olympic bomber, and many others, could have played a role toward their mental derangement that lead to their acts of terror? And, how can our society become so obsessed with marijuana with near reverential worship? There's even some evidence, albeit sketchy, the 9/11 terrorists used marijuana.

And yet in the midst of all this mayhem and madness, smoked or ingested marijuana (as opposed to legitimate marijuana medical research science) is supposed to be , ugh, 'medicine'? Who exactly are we kidding with this hoax of the grandest scale? It's all about paving the road toward national legalization, and worse, liberalization. The end result will be greater abuse at all ages, including children, potentially assuring America's downward spiral. And then, even more addiction, the horrible disease of the brain, will guarantee even greater demand. The process is wicked in every sense of the word. Totally WICKED!

My overall million dollar question is: Is dope behind the madness, and when will we know, if ever?


The sooner the Prohibitionist generation dies off, the better. Marijuana is being used to make sure that private correctional firms have a steady supply of inmates and keep lining their pockets. The most modern countries in the world never made the plant illegal to begin with. If marijuana is illegal then alcohol should certainly be the same. How often have you heard about a family being torn apart by alcohol? How about pot? Get serious. Regulate and tax it!

choice of words

Your claims about long term effects and hazards to youth caused by the use of this mythical "marijuana" seems to be filled with words such as "may" or "could have",sounds to me like it's all conjecture, you have no definitive proof of your outrageous claims, so why are you making these claims at all? You are intentionally misleading the public in an attempt to justify prohibition of cannabis, a dismal failure . Under your prohibitionist watch use of cannabis has proliferated to a point that you have lost complete control of the illicit drug trade.
You need a complete about-face in your policies. Legalize all of the illicit drugs, none of them have been proven to be any more dangerous than alcohol. You have been told time and time again, the effects of the drug laws are far worse than the effects of any drug. The public is fed up with their tax dollars continually being wasted in escalating amounts on failed prohibitions. Building more prisons and hiring more law enforcement is NOT the way to handle an illicit drug trade that is completely out of control.
Do the right thing and end prohibition

Government propaganda

Public health groups are worried of the dangers if made more widely available?
THAT ship sailed long ago!
How much more widely available could it be?
IT'S A WEED! Hello!

BILLION$ of dollars circulating into the US economy MONTHLY, rather than going to Mexican drug lords.
Quality control.
Prohibiting sales to minors.
Relief for families who need it NOW, and can't afford to wait for scientists to figure out how to ingest it without feeling 'high'.
Elimination of the market for poison 'spice' and 'bath salt' which is causing REAL harm.
Free up government resources to fight drugs like METH and CRACK that are actually as bad as the DEA says, unlike weed.
Smokers could purchase edibles to save their lungs.
People who want to get high will get high LEGALLY.

Billion$ of dollars going to Mexican drug lords instead of the US economy.
ZERO quality control.
Black market sales to whoever is buying.
Suffering families who could benefit from cannabis but suffer instead.
Legal alternatives such as 'spice' and 'bath salt' doing REAL damage to American brains.
Waste of government resources while meth and crack and heroin addiction worsens.
Smokers continue to harm their lungs with cannabis smoke as edible alternatives are unavailable.
People who want to get high will get high ANYWAY.

Legal? Or illegal?
Logical? Or illogical?

Cannabis,tobacco, and alcohol

Tobacco is a major cause of cancer, so is alcohol. Tobacco addiction rates and alcohol abuse rates are both documented as being extremely high. Alcohol causes people to kill others regularly with their vehicles. People smoke tobacco at work, and some even consume alcohol at company sponsored events. Each of these two are just as bad as agonists, so why is cannabis a Schedule 1 controlled substance? Tobacco has no medical use at all. Alcohol doesn't really have a medical use except as a base for many other drugs. Isn't it time to reevaluate cannabis? Cocaine, meth, and heroine are all more addictive and deadly if overdosed whereas no one has died of a cannabis overdose. So again... Time to reevaluate?

Medical use of marijuana

In 2003 NIH did research and the US government put a patent on the successfull research. NIH found that with the use of certain parts of the plant they were able to kill cncer cells, of course this was in the lab and the were using mice, but the experiments showed promise. They also took a health volunteer and this person consumed 700mg of CBD for an extended duration with little to no side effects. Yet this is not available for anything but the synthetic CBD is through prescription with numerous side effects. I wont argue over the long term effects of smoking cannabis are but to eliminate a person of cancer it would be short term, and this person would more than likely quit using the medicine if they were found clear of cancer.
Just wondering what research is being done for cancer not just the vomiting due to chemotherapy but to actually kill the cancer using the marijuana plant.

Research on the anti-cancer

Research on the anti-cancer effects of CBD and other ingredients in marijuana is funded by the National Cancer Institute. This page gives an overview of what is known about cannabinoids in relation to cancer treatment: http://www.cancer.gov/about-cancer/treatment/cam/patient/cannabis-pdq/#link/_13

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    Cite this article

    NIDA. (2015, April 28). Taking a Science-informed Approach to Medical Marijuana. Retrieved from https://www.drugabuse.gov/about-nida/noras-blog/2015/04/taking-science-informed-approach-to-medical-marijuana

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    Welcome to my blog, here I highlight important work being done at NIDA and other news related to the science of drug use and addiction.

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