Cannabis & Stimulants: Unraveling Overdose & Psychosis Risks with Silver Hill Hospital’s Dr. Rocco Marotta

The Dorm, a leading young adult mental health treatment program (IOP) based in New York City and Washington, D.C., recently hosted a collaborative continuing education event featuring Rocco Marotta, MD, PhD, Director of the Center for the Treatment and Study of Neuropsychiatric Disorders at Silver Hill Hospital. The focus of his presentation was the connection between cannabis, stimulants, psychosis, and overdose rates in young adults. The article following captures his professional insights for our audience.

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Dr. Rocco Marotta has decades of experience working with clients with schizophrenia, and in a recent presentation for mental health professionals, shared his extensive expertise in witnessing an alarming rise in psychosis and overdose incidents in his clinical practice.

His presentation explored how increased cannabis use—reported by 42% of young adults in 2023—along with the growing potency of cannabis (an average THC concentration of 16% in 2022 compared to 4% in 1995) contributes to these trends. The following article summarizes highlights from the presentation, including the compounding risks associated with stimulant use and the interplay of brain biology, genetic predisposition, and environmental factors.

To begin his presentation, Dr. Marotta presented us with data from his own clinical practice, where the cases presenting with psychosis overwhelmingly revealed cannabis use or treatment with stimulants. Out of 30 individuals with treatment-resistant schizophrenia spectrum disorders, 20 had a history of either or both cannabis and stimulant use.

Even with this numerical and anecdotal evidence, he acknowledges that the cultural zeitgeist often presents cannabis as a safe alternative to other drugs or alcohol, when that is clearly not the case for vulnerable individuals.

High-potency cannabis and other substances, such as stimulants, have been linked to psychosis and overdose, which is why clinicians must continue to share their research and insights into anecdotal case studies around substance use.

Dr. Marotta went on to demonstrate the stark data showing how the potency of cannabis has been steadily on the rise over the past half a century, which is a globally occurring phenomenon.

What has also been found in research is the correlation between potency and psychosis. Data from King’s College in London compared the average cannabis potency in major European cities to the adjusted rates of admissions to emergency rooms for psychotic behavior, and found a moderate correlation between the two. Furthermore, data from Canada demonstrates a link between the legalization of cannabis and all cannabis-related visits to the emergency room, including incidents of psychosis. Dr. Marotta shared that there was a 40% increase in hospitalizations due to psychosis after the commercialization of cannabis.

The legalization of cannabis is an overwhelmingly relevant subject in today’s world. Minority populations have been disproportionately impacted by criminalization of cannabis, and now that commercial use of cannabis is legal in many states across the U.S., it is even more important to ensure that safeguards for social justice are in place. Legalization is both a step forward in terms of social reform, as well as a new concern to be cautious of in terms of physical and mental health impacts. At the same time, as the popularity of cannabis grows, t is necessary to have

To delve further into the observable mental health impact of cannabis, Dr. Marotta explained that clinicians have found that cannabis exposes a vulnerability to psychosis, and may also induce a process of converting to a full diagnosis of schizophrenia or related disorder.

To illustrate this, he shared a study which found that 26% of individuals who have experienced cannabis induced psychosis had a conversion to a schizophrenia spectrum disorder diagnosis within the next three years, as opposed to a 0.1% instance rate of schizophrenia in the general population. This is particularly present in adolescent and young adult males, whose transition rates average to 41.3% and 40.1% respectively. These rates, however, only appear in people who were already predisposed to psychosis—the same data shows that those who have used cannabis without incidence of psychosis have a 1.9% rate of conversion to a schizophrenia diagnosis.

Similarly, a study from Denmark showed that cannabis use is much more likely to induce schizophrenic changes when compared to other substances. And as Dr. Marotta explained, “When they tease out their data, when they give it to the statisticians, the data coming out of Scandinavia says that 15% of the cases of young people showing schizophrenia might have  been prevented if they weren’t using cannabis.” This is a notable number and further emphasizes the need for caution in vulnerable populations.

On a final note, Dr. Marotta mentioned that historically, young women do not show as much psychosis as young men do, and thus were less often diagnosed with schizophrenia. However, this is now changing: Canada’s health infobase cites that in 2022, incidence of hospitalizations for schizophrenia in 15-19 year-old teenagers were shown to have nearly the same rates for young men and women. The reasoning for such is not made explicitly clear, but as the rates of cannabis use among young people rise, Dr. Marotta has warned us of this alarming trend and how it may continue into the future.

Referring back to the introduction of his presentation, where shared that in his practice, he says that out of 30 individuals with treatment-resistant schizophrenia spectrum disorders, 20 had a history of either or both cannabis and stimulant use, Dr. Marotta went on to further explore the role of combining cannabis & stimulants.

He shared data from McLean Hospital, which claims that high doses of prescription stimulants, such as the commonly used amphetamine Adderall for ADHD, may also be associated with increased psychosis risk. These psychotic states can be indistinguishable from schizophrenia and may even be irreversible. Ritalin, another common prescription medication for ADHD, did not show the same effect.

But this again demonstrates the susceptibility to psychosis in a particular subgroup of the population.

Dr. Marotta went on to share that when doctors think about variables for illnesses, they think in terms of two or three “hits.” In cancer, for example, the two “hits” could be an underlying vulnerability and an exposure to a toxin, which could then together start a process of cancer onset. In terms of schizophrenia, Dr. Marotta shared his concerns for what some societal “hits” could be—cannabis and stimulant use, high stress levels, socioeconomic factors, or even exposure to violence.

Additionally, substance use is on the rise for our younger population. Estimates of regular cannabis use among high school- and college-aged students are around 50%, many of whom also take stimulants. (47% of teenagers involved in insurance-based programs are prescribed stimulants, and many more likely take them without prescription.) Additionally, 50% of the psychiatric admissions in the city are schizophrenia-related. The large cities in the U.S. are and will continue to be impacted in major ways—especially as the commercialization of cannabis begins to become more and more prevalent.

“I think back to my younger days when nothing [related to cannabis] seemed harmful. Now, I see danger, and I see the impact this has on young people,” reflected Dr. Marotta.

As he concluded his presentation, Dr. Marotta explained that schizophrenia is a complex disorder of development, where changes in behavior, relativity to others, and cognition are all present. In the brain, clinicians can see a disruption in the frontal lobes, involved in attention; the hippocampus, involved in memory; and the amygdala, involved in emotional control.

When cannabis and amphetamines are used, we know that these brain structures are damaged, as they interfere with the regenerating parts of the brain. Stress is also a point of damage to these symptoms. So, during a critical period of development and learning, young adults are living in environments with enormous stress and taking substances to relieve symptoms of stress, both of which can damage critical cell structures and accelerate degeneration.

There are medications that can protect these cell systems from damage—antidepressants, for example, and clozapine, an antipsychotic. Dr. Marotta’s own collaborators have demonstrated effectiveness when changing prescription medicine from Adderall to antipsychotics in an individual who demonstrated symptoms of psychosis co-occurring with cannabis use.

In closing, Dr. Marotta stressed that populations vulnerable to psychosis should be aware of the risks and growing potency of cannabis in the United States, and clinicians must continue to study its impact both anecdotally and through the broader body of research available internationally to help educate the public about the complexities of cannabis use, stimulants, and psychotic disorders that can lead to growing overdose rates.