Marijuana legalization: an unpopular view

In the mid-1990s, a few pharmaceutical companies made broad claims regarding the safety and efficacy of opioid medications for pain management. These claims were based on limited research that did not fully account for these drugs’ potentially harmful effects. As a result, we are now facing an opioid epidemic across the United States.

Now, New Jersey joined several other states by legalizing marijuana for recreational use. While there are clear differences between opioids and marijuana, we may be making the same mistake without realizing it. Like opioids in the ’90s, we lack adequate clinical research to make informed decisions about the safety and benefits of marijuana use.

This is why physicians with experience treating patients with substance use disorders ask people to think twice when considering this important public health issue.

Marijuana is designated as a Schedule I controlled substance. That means it’s illegal under federal law, and also that the scientific research that we can do is limited. If that designation changes, then we’ll learn about its benefits—but right now, we know a lot more about the potential harm.

From the current research on marijuana, we can tell you that there are some well-defined health risks. These include the risk of psychosis, which can be thought of as a loss of contact with reality along with symptoms such as delusions (false beliefs) and hallucinations (seeing and hearing things that others do not). Other serious risks include cognitive decline (confusion or memory loss) and addiction, which includes a documented withdrawal state (symptoms associated with stopping drug use).

Risk of psychosis with cannabis use

Cannabis use and psychosis are clearly associated. In comparison to healthy individuals, those who exhibit psychotic symptoms including delusions, hallucinations, disorganized speech and behavior are at greater genetic risk for impaired function and have higher rates of cannabis use disorder (CUD). This risk increases in a dose-dependent manner, meaning you are more likely to develop the above symptoms as your consumption increases. This is particularly important in the child and adolescent patient population who are likely to have increased access to cannabis if legalized for recreational use. It’s recommended that a child or teen with a family history of psychosis or subclinical symptoms not use marijuana–but doctors won’t always know that history.

We’re starting to see concerns that high potency forms of cannabis might be linked to higher risks of psychosis. The legalized recreational market in the U.S. is distributing stronger forms of cannabis through vaping, dabbing, and rosin. In the early 1990s, the average tetrahydrocannabinol (THC) content confiscated was 3.7%, but in 2014 that number rose to 6.1%. The most potent cannabis products are butane hash oil, which can have a THC content of up to 80%. In states that pass recreational marijuana laws, legally purchased cannabis’s potency is a relevant public health concern.

Risk of irreversible cognitive decline

A recent study followed 1,037 individuals from birth to age 38 and checked for cannabis use in young adulthood. The younger a person is and the more consistent the use of cannabis, the more impaired they become across all cognitive domains. Impairment was concentrated among adolescent-onset cannabis users, with more persistent use associated with greater decline. The researchers noted individuals who started using cannabis in adolescence lost an average of 8 intelligence quotient (IQ) points, while those who used cannabis as adults had no decline in their IQ score. Cessation of cannabis use did not fully restore the lost function, suggesting a neurotoxic effect of cannabis on the adolescent brain.

Risk of cannabis use disorder and withdrawal

It’s common among proponents of legalized marijuana to say that cannabis use disorder (CUD) is rare, and the symptoms do not impair function the way other drugs do. But a 2016 study found that one in five lifetime users met the criteria for CUD, of those users 23% had severe CUD. The symptoms people with CUD can include anxiety, restlessness, depression, irritability, insomnia, vivid dreams, tremors, and decreased appetite. Furthermore, 48% of those in the study with severe CUD were not functioning in any major role, such as keeping a job. Withdrawal is most severe during the first week but can persist for up to one month after discontinuation—and it shows up in 33% of regular users in the general population and 50-95% among heavy users in treatment. It can impair people and often leads to cannabis or other substances use to relieve the symptoms.

The debate is likely to continue as both sides are passionate about their position. There is still a great deal to learn about the potential medical benefits and risks of cannabis use. While the risks of marijuana are different from opioids, they are no less real. Before deciding that cannabis is safe and beneficial, we need to first change the schedule I status of cannabis. This will help provide an evidence base for consumers to make an informed decision. I urge you to carefully consider the risks and benefits of cannabis use. Your health and that of your children may be at stake.