By Greg Ganske

November 7^th, 2025

Today’s marijuana weed is significantly stronger than when the Baby Boomer generation of the 1970s and 1980s smoked marijuana in college. Back in those days the amount of tetrahydrocannabinol (THC), the psychoactive compound in cannabis that causes the “high,” was 1-3% in marijuana.

Even as recently as the 1990s a typical joint contained only about 5% THC. Today cannabis flower alone often contains 20-30% THC.

This huge increase in potency is due to genetic selection and advanced growing techniques. Today’s cannabis products, especially concentrates like that used in “dabbing” which uses concentrates like waxes, oils, and shatter (a butane hash oil—BTO), can reach THC levels approaching 90%.

A small amount of these high concentrate substances produces a strong and immediate high with effects of euphoria and relaxation. However, the high levels of THC also can produce anxiety, paranoia, panic attacks, and an increased heart rate.

This is particularly worrisome in teenagers. Depression and anxiety are byproducts of frequent marijuana use in the young besides symptoms of delusion. Adolescence is a critical period of brain development when the brain is so-called plastic, developing neuro connections.

Using marijuana during this time interferes with the endocannabinoid system which plays a role in regulating emotions and cognitive functions.

A new study in April’s JAMA Psychiatry on marijuana and psychosis is being widely reported in the press (Ahrens, “Convergence of Cannabis and Psychosis on the Dopamine System, JAMA Psychiatry, April 9, 2025).

By using a type of MRI, researchers from McGill University discovered a dose-dependent rise in dopamine signals corresponding to the severity of Cannabis Use Disorder (CUD) symptoms that mirror those seen in untreated psychosis.

The paper showed an association, not necessarily a cause, of a biologic link between cannabis use and the risk of developing a psychosis. It suggests that cannabis use could accelerate the onset of schizophrenia.

This study provides strong neuro-biological evidence supporting the association between cannabis use and psychosis risk that is seen in longitudinal studies from Sweden, the Netherlands, Germany, France, Australia, and New Zealand (World Psychiatry. 2008, Jun; (2) 68-71.)

The most plausible hypothesis of this association is that cannabis use, especially frequent use with high doses of THC, may precipitate schizophrenia in young persons who are vulnerable because of a personal or family history of schizophrenia. One of these studies speculated that 13% of cases of schizophrenia could be averted if all cannabis use were prevented.

It is not surprising that marijuana abuse in adolescents (10 to 19 years of age.) is a risk factor for schizophrenia. It is well established that alcohol abuse in adolescents is a risk factor that can trigger mental illness in vulnerable individuals.

There is strong evidence of a complex and bi-directional relationship between alcohol abuse and schizophrenia with both genetic and environmental factors playing a role. Early alcohol use can also trigger the illness in adolescents.

The adolescent brain is still developing, and frequent and heavy alcohol use can disrupt the development of the impulse and control center in the prefrontal cortex. Alcohol, like marijuana, also has effects on the dopamine system. Excessive drinking can induce alcohol-induced psychosis (AIPD) leading to hallucinations and delusions.

Some cases of AIPD evolve into chronic, schizophrenia-like syndromes. As with marijuana, studies have shown a “does-dependent” relationship between alcohol use and mental health symptoms. As with marijuana, the risk and severity of symptoms increases with the frequency and intensity of use. Neurological changes caused by early drinking may persist in adulthood.

In light of increased knowledge of the association of marijuana use with mental illness, it is a matter of public health for the FDA to regulate marijuana just as The Alcohol and Tobacco Tax and Trade Bureau (TTB) regulates the production, labeling and advertising of alcoholic beverages and as the FDA regulates tobacco.

In September 2012 and August 2022, I wrote two opinions on marijuana in the Des Moines Register (“It is Time to Legalize Recreational Marijuana in Iowa and Nationally” and “I Still Think Marijuana Should Be Legal: Moderation In All Things”). I advocated state and federal legalization primarily to provide a legal marijuana product that is free of lethal drugs such as fentanyl.

In the United States cannabis is legal in 40 of the 50 states for medical use and 24 states for recreational use. The patchwork of state-by-state regulations is problematic. Regulating marijuana products under the FDA’s rigorous review process would ensure they were safe from heavy metals, bacteria and mold, and pesticides that have been found in both the illegal and legal cannabis supply.

These contaminants pose a significant health hazard for both recreational and medical users. Because of the current Class 1 classification of marijuana grouping, it with narcotics and dangerous drugs the FDA and the EPA has not provided guidance on regulating contaminants to the states. This has left the states to determine helter-skelter on their own how to protect cannabis users.

Federal legalization would allow for traditional research and drug development processes ensuring that marijuana products are safe and effective for their uses. FDA oversight would prevent misleading claims about cannabis products. We need better research on whether cannabis really is effective. For instance, does marijuana provide effective pain relief for multiple sclerosis or does it actually cause unfavorable side effects?

Legalization would help ensure accurate labeling on potency and potential side effects. The FDA could issue warnings like those seen on tobacco products, especially for high-potency concentrates and cannabis-infused food and drinks.

Regulation of tobacco by the FDA has controlled nicotine content and the FDA is currently proposing further reduction in nicotine. Its public relations crusade against tobacco products has been effective in reducing tobacco use.

The FDA should similarly devise a national advertising, educational and prevention campaign warning about the abuse of marijuana and how it could lead to mental health disease especially in the young. Such campaigns have been effective for instance in warning pregnant women about the dangers of drinking alcohol.

Legalization would generate tax revenue that could be used to fund public health programs on the dangers of marijuana abuse. Federal legalization would end the conflict between federal and state laws. Congress would need to act on this as well as the FDA reclassifying the Controlled Substance Act classification of marijuana.

I would envision setting up a separate FDA division for marijuana similar to that I proposed in legislation back in 2000 which eventually served as a basis for the Tobacco Control Act of 2009.

In the meantime, parents and doctors should be advising young individuals to avoid using cannabis. At a minimum, they should counsel delay marijuana use until at least early adulthood. If a child starts experiencing unusual behaviors such as isolating, talking to themselves, or hearing or seeing things that others don’t, psychological treatment should be sought right away. Marijuana use might be involved.

Warning—this isn’t your grandmother’s weed anymore!

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Greg Ganske, MD, Member of Congress (ret), is a retired plastic surgeon who cared for women with breast cancer, children with cleft lips, farmers with hand injuries, trauma and burn patients. He served Iowa in Congress from 1995-2003 on the committee with oversight of the FDA and EPA.