A new study from the University of Michigan has found that marijuana addiction rates among US adults aged 40 to 50 have nearly doubled since 2017, and public health experts are pointing directly at state legalisation as the driving force.

The Numbers Behind the Headline

The annual analysis, drawn from self-reported drug use data collected through National Institutes of Health surveys, found the share of 40 to 50 year olds reporting symptoms of cannabis use disorder rose from 3.3% in 2017 to 6.5% last year, a jump of roughly 97%. The study was funded by the National Institute on Drug Abuse, and defines the disorder using recognised clinical markers: consuming large amounts, using marijuana longer than intended, being unable to stop, continuing use despite dangerous circumstances, experiencing withdrawal, and neglecting responsibilities as a result.

Megan Patrick, the study’s lead researcher, was clear about what the data actually captures. This isn’t casual, consequence-free use, she said, the index reflects people who report that their cannabis use is genuinely harming their lives.

Daily use is also climbing. Among 19 to 30 year olds, daily marijuana use rose from 6.9% in 2015 to 11.8% in 2025. Among 35 to 50 year olds, the figure sits at 8.5%. Separately, 11.4% of young adults reported using intoxicating hemp-derived THC products such as Delta-8, Delta-10 and HHC within the past year. At the same time, the same survey found cigarette smoking at historic lows and a decline in alcohol consumption, so this isn’t a broad rise in substance use, it’s something specific to marijuana addiction rates climbing on their own.

What the Federal Government Is Seeing

Nora Volkow, director of the National Institute on Drug Abuse, said the findings line up with her agency’s own estimate that roughly 30% of all cannabis users become addicted. She pointed to several factors behind the trend, including more people using cannabis to self-treat medical conditions, declining public perception of risk, and greater dispensary density in areas where legalisation has taken hold. She also flagged social media as a significant driver normalising the use of increasingly potent strains, and noted that heavy, frequent marijuana use has increased roughly fifteenfold since the early 1990s.

Dr Volkow welcomed the Trump administration’s recent decision to reclassify marijuana, saying it would help reduce research barriers, even though the drug remains illegal at the federal level.

Legalisation as the Main Culprit

Robert Brock, a vice president at telehealth company NuggMD, said cannabis is simply far more available and normalised than it was five, let alone nine, years ago, and that easier access means more people are self-medicating without ever consulting a doctor.

Keith Humphreys, a Stanford University psychologist who studies addiction, was blunter still, arguing that the cannabis industry operates with the same profit-driven, aggressive playbook as the tobacco industry once did, built on fostering addiction rather than casual use.

Kevin Sabet, president of Smart Approaches to Marijuana, an organisation that tracks cannabis-related harms, said the rising marijuana addiction rates should alarm anyone who assumed legalisation wouldn’t drive up dependency. More customers buying stronger products more often, he argued, isn’t an accident of commercialisation, it’s the business model functioning as intended. His organisation notes that average THC content in marijuana plants has climbed from around 1 to 3% in the 1970s to 18 to 23% today.

Health Risks That Come With the Territory

Research has consistently linked marijuana use to higher rates of hospitalisation, impaired driving and reduced productivity. Federal studies also cite elevated risks for suicide, stroke, heart attack, psychotic disorders, uncontrollable vomiting and chronic lung conditions, risks that increase notably as users age toward retirement.

A separate, sweeping review of randomised clinical trials published in the Journal of the American Medical Association found insufficient evidence to support many of the medical claims made about cannabis, including its popular use for insomnia and pain relief. That review also flagged cardiovascular and psychiatric risks and urged doctors to warn patients more clearly.

Workplace data adds another dimension. Quest Diagnostics, the country’s leading drug-testing lab, found marijuana accounted for 52.5% of positive hair drug tests last year, with the share of marijuana-positive workers rising 58.9% since 2021. Jason Hudson, the company’s scientific and laboratory director, said the data points to a sizable share of the US workforce using drugs, primarily marijuana, on a recurring basis, a particular concern in safety-sensitive industries.

Not Everyone Blames Legalisation Alone

Some clinicians pushed back on framing legalisation as the single cause. Dr Allen Masry, an addiction psychiatrist and medical director at All in Solutions treatment centres, called that framing an oversimplification, arguing that problem use will stay high until prevention and treatment systems are built out to match demand.

Dr Charles Smith, medical director at the Agape treatment center in Florida, cautioned that self-reported symptoms aren’t the same as a formal diagnosis, and argued policy should move toward accurate potency labelling, clear warning labels, responsible marketing rules, routine screening for cannabis use disorder, and better access to treatment, rather than leaning on moral condemnation.

Jerry Joyner, a Texas-based cannabis advocate, placed blame on marketing rather than the drug itself, arguing that rebranding cannabis as “wellness” or “self-care” has fuelled the rise, and called for restrictions on advertising alongside honest labelling of potency.

The Bigger Question Over Regulation

Marijuana remains fully illegal in just five US states: Idaho, Kansas, Nebraska, Wyoming and South Carolina. Henry Maxwell, a Colorado-based addiction counsellor and former addict, suggested that state-level legalisation decisions have often been driven as much by tax revenue as by public health reasoning, pointing to cannabis tax dollars now funding schools and infrastructure in several states.

Jonathan Caulkins, a public policy professor at Carnegie Mellon University, argued that excise taxes remain one of the most effective tools for curbing harm from psychoactive substances, but only when paired with genuine enforcement against illegal sellers undercutting licensed producers, something he says the country has largely lacked the political will to pursue. He pointed to cigarette taxation and advertising restrictions as evidence the approach can work.

A recent Gallup poll found 17% of US adults reported using marijuana in July, matching a 2023 record high, including 15% who used edibles. In the same survey, cigarette smoking and alcohol consumption both hit record lows, at 11% and 54% respectively, while 9% reported vaping and 4% used nicotine pouches.

Where Treatment and Prevention Fit In

Justin Szela, clinical director at Pinnacle Peak Recovery in Arizona, said the more durable path to recovery lies in helping people find alternative ways to manage stress, sleep and loneliness, rather than relying on the substance that was masking those problems in the first place. That sentiment echoes across much of the expert commentary here: whatever the disagreement over legalisation’s exact role, there’s broad consensus that prevention education, accurate potency labelling and accessible treatment haven’t kept pace with how fast marijuana addiction rates, and cannabis use disorder more broadly, have grown across the US.

Source: Washington Times