Why Today’s Marijuana Is Nothing Like the Plant of the 1960s

A new commentary from authors Sue Homola and Dr Raymond Wiggins is drawing attention to a fact that hasn’t kept pace with public perception: the marijuana available today bears little resemblance, chemically speaking, to the plant smoked a generation ago, and the potency shift carries consequences that are only now becoming clear.

Same Name, Different Drug

Back in 1969, marijuana averaged around 1 to 2 per cent THC, the compound responsible for its intoxicating effects. Today that average sits closer to 22 per cent, with specialty strains exceeding 35 per cent and concentrated products approaching nearly pure THC. According to Homola and Wiggins, this leap did not happen by chance. It came through deliberate selective breeding, chemical mutagenesis, and induced genetic mutation, techniques aimed squarely at maximising potency. High-potency marijuana, in other words, is a manufactured product, not a natural constant.

Follow the Money

The scale of the shift is matched by the money behind it. Marijuana grew into a $38.5 billion industry in the US in 2024 alone, with the authors noting involvement from established players in tobacco, pharmaceutical and alcohol sectors, industries with long histories of marketing addictive products at scale. State legislatures, they argue, have increasingly positioned themselves as intermediaries in that process, legalising recreational use while simultaneously taxing it as a revenue stream.

Legalisation has expanded rapidly since 2012, when a shift in federal enforcement priorities opened the door to broader commercialisation. Roughly half of US states now permit recreational sale, and a majority allow therapeutic use, a legal landscape further complicated by federal rescheduling changes affecting high-potency marijuana products for therapeutic purposes.

Nobody Thinks It’s Dangerous Anymore

As availability has spread, so has the perception that marijuana carries little risk. The authors point to dispensaries now outnumbering some fast-food chains in parts of the US, alongside a striking generational shift in attitudes: survey data cited in the piece indicates that around 79 per cent of eighth graders see no risk in trying marijuana, despite the physical and mental health concerns it poses, particularly to those under 25.

That shift in perception has coincided with a rise in cannabis use disorder, which the 2025 National Drug Survey put at 20.6 million people over age 12 in the US.

What It Does to a Brain That Isn’t Finished Growing

The authors’ central concern is what today’s high-potency marijuana does to young, still-developing brains, a process that continues well into the mid-20s. They cite research linking early use, before age 18, to a 37 to 70 per cent higher likelihood of depression in adulthood, and daily use to a 2.5 to 3.2 times greater risk of anxiety by age 29. A 2020 study in JAMA Psychiatry found a 92 per cent higher risk of anxiety disorders among users of high-potency products, the category the authors say now dominates the market almost entirely.

One of the more serious risks flagged is cannabis-induced psychosis, which the authors note converts to a diagnosis of schizophrenia or bipolar disorder in roughly half of cases within a few years.

Who’s Actually Going to Fix This

Homola and Wiggins trace part of the shift in youth attitudes to a decline in federal funding for drug-prevention education, which they say began around 1991 and has never fully recovered in school-based prevention curricula since. Their conclusion places the weight of response not solely on policymakers, but on parents, teachers and health professionals closest to young people, arguing that honest, fact-based conversations about high-potency marijuana are what will keep the next generation from becoming what they describe as the industry’s next customer base.

Their book, The Blunt Truth: Ten Things Every Parent Needs to Know About Marijuana, expands on this argument, framing it as a resource for families navigating a legal and cultural landscape that looks very different from the one their own parents faced.

The Gap Between What We Think and What’s True

The throughline in this commentary is simple: the word “marijuana” today describes a substance that is chemically and commercially unrecognisable from what it meant even twenty years ago. Whatever position people hold on legalisation itself, the underlying potency data is difficult to dispute, and it’s exactly that gap between public perception and current reality that the authors argue families and educators need to close.

Source: dbrecoveryresources