Cannabis is a hell of a drug. It can treat inflammation, pain, nausea, and anxiety, just to name a few ailments. But like any drug, cannabis comes with risks, chief among them something called cannabis use disorder, or CUD.

Studies show that an estimated 9 percent of cannabis users will develop a dependence on the drug. Think of CUD as a matter of the Three C’s, “which is loss of control over use, compulsivity of use, and harmful consequences of use,” says Itai Danovitch, chair of the department of psychiatry and behavioral neurosciences at Cedars-Sinai. A growing tolerance can also be a sign.

Compared to a drug like heroin, which can hook a quarter of its users, the risk of dependency with cannabis is much lower. The symptoms of withdrawal are also far less severe: irritability and depression with cannabis, compared to seizures and hallucinations with heroin. Plus, an overdose of cannabis can’t kill you.

But as medicine and society continue to embrace cannabis, we risk losing sight of the drug’s potential to do harm, especially for adolescents and their developing brains. Far more people use cannabis than heroin, meaning that the total number of users at risk of dependence is actually rather high. And studies are showing that the prevalence of CUD is on the rise—whether that’s a consequence of increased use due to legalization, a loss of stigma in seeking treatment, or some other factor isn’t yet clear. While cannabis has fabulous potential to improve human physical and mental health, understanding and then mitigating its dark side is an essential component.

Dependence is not the same as addiction, by the way. Dependence is a physical phenomenon, in which the body develops tolerance to a drug, and then goes into withdrawal if you suddenly discontinue use. Addiction is characterized by a loss of control; you can develop a dependence on drugs, for example steroids, without an accompanying addiction. You can also become addicted without developing a physical dependence—binge alcohol use disorder, for instance, is the condition in which alcohol use is harmful and out of control, but because the use isn't daily, significant physical dependence may not have developed. “An important similarity that all addictive substances tend to have is a propensity to reinforce their own use,” says Danovitch.

Cannabis, like alcohol or opioids, can lead to both physical dependency (and the accompanying withdrawal symptoms) and addiction. But the drug itself is only part of the equation. “The risk of addiction is really less about the drug and more about the person,” says Danovitch. If it was just about the drug, everyone would get hooked on cannabis. Factors like genetics and social exposure contribute to a person’s risk.

Another consideration is dosing. Cultivators have over the decades developed strains of ever higher THC content, while the compound in cannabis that offsets THC’s psychoactive effects, CBD, has been almost entirely bred out of most strains. Might the rise in the prevalence of CUD have something to do with this supercharging of cannabis?

A new study in the journal Drug and Alcohol Dependence found that for individuals whose first use of cannabis was with a high THC content (an average of around 12 percent THC) had more than four times the risk of developing the first symptom of CUD within a year. (Two caveats being: the participants in this study had a history of other substance abuse disorders, and this looked at the first symptom of CUD, not a full-tilt diagnosis.)

Figuring out such details improves the odds that we’ll be able to detect and treat cannabis use disorder. “Early intervention is important to address substance use before it progresses to a substance use disorder,” says Iowa State University psychologist Brooke Arterberry, coauthor of the study. But to pull that off, she says, we need to better understand when and why symptoms emerge.