Roger Roffman, a cannabis dependence expert and professor emeritus of Social Work at the University of Washington,told Leafly: “Addiction results from a combination of biological and psychological factors that contribute to conditioned behavioral patterns that are very difficult to stop or resist.”
Jim Anthony, another leading cannabis dependence expert and Michigan State University professor of epidemiology and biostatistics, says that the classic distinction made among the public between “psychological” and “physiological” addictions is not helpful. He said people who are dependent on cannabis can experience withdrawals when they cut back that might be classified as psychological—like depression or anxiety—or symptoms which can be classified as physiological—like insomnia and appetite disturbance.
“Withdrawal is the mirror image of what the drug does. If cannabis makes you mellow, then you’re irritable, grumpy,” said Dr. Alex Stalcup, medical director of rehab facility New Leaf Treatment Center Stalcup. “For many people, that’s really unpleasant. Especially the irritability, that gets a lot of my patients into trouble.”
Now, let’s take a look at how common that is. ‘Cannabis Use Disorder’
(Photo by Nina Ruecker/Getty Images)Scientists and medical professionals don’t use the phrase “marijuana addiction” much these days. Instead, they’ve adopted the name “cannabis use disorder,” which is now listed in the official manual of psychiatric diagnoses, the DSM-V.
This manual’s criteria and definitions are universally recognized in the U.S. when it comes to treatment recommendations. DSM-V uses 11 indicators to characterize cannabis use disorder. These indicators include various behaviors centered around marijuana use, including craving weed, time spent consuming weed, and repeated failed attempts to cut back.
According to the DSM-V, the more of these 11 factors an individual experiences, the more severe the cannabis use disorder. A large-scale survey done in 1994, and a follow-up from 2010, found a nine percent transition rate from cannabis use to dependence. The numbers are real but certainly less significant than the addiction rate for nicotine which is 67.5 percent and the addiction rate for alcohol which is 22.7 percent. Drug Courts Take This Seriously
This matters because governmental entities like drug courts take conditions listed in the DSM-V very seriously. In many states, “drug rehab” programs are mandated for substance-related crimes, including cannabis possession arrests.
What this means is that if you’re unlucky enough to get busted,you could be defined as having cannabis use disorder if you meet as few as two of the 11 defining criteria. (This is controversial among experts as the DSM used to require that people met a minimum of three of the 11 criteria to qualify.)
Let’s say you have #4 (a strong desire to use cannabis) and #10 (needs markedly more cannabis to achieve the desired effect), that would be enough to get you a diagnosis of at least “minor” cannabis use disorder.
“If there’s a difficulty with [the DSM-V’s diagnostic criteria], it’s overreacting when just one or two of these indicators are present,” Roffman explained. This overreaction dilutes instances of legitimate need for help with situations in which cannabis is neutrally or positively impacting someone with no desire to quit.”
Roffman, while acknowledging that cannabis can be used moderately and responsibly, says “the fact of the matter is we have a substantial minority of cannabis users who experience far more than one or two of these diagnostic criteria.”“We need to be compassionate to people for whom a moderate or severe disorder exists, and we need good science to understand it and find ways of helping,” Roffman said.
Does Criminalization Reduce Addiction? Does Legalization Increase It?Historically, the government’s response to drug addiction in the U.S. has been to criminalize drugs.
It has become increasingly obvious to many Americans that this prohibitionist approach demonstrably does not work. In fact, it seems to exacerbate the problem.
“All of the messages about health risks under prohibition are skewed in terms of overstating and sometimes blatantly misrepresenting science,” Roffman said. “Under legalization, we have a lot more room to speak about the continuum of health benefits, possible health risks, and how to make good decisions.”
Genetics and Mental Health are Likely FactorsGenes are one strong predictor of addiction, according to Dr. Alex Stalcup, medical director of rehab facility New Leaf Treatment Center in Lafayette, Calif., reports Healthline. Studies of identical twins raised separately support this genetic theory. Separated identical twins still have higher rates of co-occurring addiction than separated fraternal twins.
Another factor playing a large role in risk of addiction is mental illness, with roots in both genetic and environmental causes.
“Mental health is a huge risk factor for addiction,” Stalcup said. “Drugs work very well, at first, for mentally ill people. If you’re anxious, it’ll go away with a couple of hits, a beer. It’s like magic. But then, the tolerance sets in. […] It works at first, it turns on you, it stops working, and then you still have a problem.”
Stalcup estimated that 50 to 60 percent of marijuana users his facility treats have some sort of mental illness. The majority he sees have depression, anxiety, PTSD, or schizophrenia, he said. 
(Photo by: Sergi Reboredo/VW PICS/UIG via Getty Images)Addictive Personalities?A recent study examined drug users who came to the emergency room with drug-related problems, a strong indicator that something is out of control. Ninety-one percent of drug users whose primary drug of choice wasn’t marijuana met the criteria for abuse. In comparison, 47 percent of users whose primary drug of choice was marijuana met those abuse criteria.
Of the cannabis users, the 47 percent who met the criteria for abuse were also more likely to smoke tobacco and to binge drink than the nonusers. These are potential warning signs that those individuals may naturally run a greater risk of substance abuse in general.
“If you are getting in trouble because you are using or going after an illegal drug, the illegality, and the fact that you don’t stop, and the fact that you keep getting in trouble over it, says that you have a high degree of a substance use disorder and that you need treatment,” said Michael Kuhar, Ph.D., a professor of neuropharmacology at Emory University’s School of Medicine, and author of The Addicted Brain: Why We Abuse Drugs, Alcohol and Nicotine. “If you’re doing something that’s wreaking havoc in your life, you need help. Forget what we call it.”