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Marijuana and Psychosis: Experts Suggest A Complicated Link



Opinion by David L. Nathan and Peter Grinspoon

Originally published on CNN on Feb 8th, 2024

In the realm of cannabis-related concerns, few issues have garnered as much attention as the potential link between marijuana use and psychosis. Explored extensively by the media, the question persists: Does cannabis truly cause psychosis and related conditions like schizophrenia, or is this connection overstated? This opinion piece by David L. Nathan, MD, and Peter Grinspoon, MD, that was originally published on CNN delves into the complexity of this issue, shedding light on the multifaceted relationship between cannabis and psychosis.

The well-established association between cannabis use and psychosis is acknowledged, but the authors caution against assuming causation based solely on correlation. Drawing a parallel with unrelated phenomena, the authors emphasize that correlation does not necessarily imply causation. Defining psychosis as a break with reality, encompassing delusions, hallucinations, and disordered thinking, the authors highlight cases of psychosis emerging in the context of cannabis use throughout their clinical work. They acknowledge the correlation between cannabis use and psychosis but argue that available evidence does not support a simplistic view of causation.

Here are the main points from the arguments raised by the authors

Complex Association

Correlation between cannabis use and psychosis is well-established, but causation remains uncertain. The authors issued caution against assuming causation based solely on correlation.

Plausible Connections

The authors present several plausible connections that complicate the relationship between cannabis and psychosis. People at risk for psychosis may self-medicate with cannabis before the onset of a psychotic disorder, suggesting that cannabis use may not necessarily cause psychosis but rather be a response to emerging symptoms.

Exacerbating Existing Psychosis

Additionally, cannabis could trigger or worsen psychosis without being the primary cause, similar to other drugs known to induce substance-induced psychosis.

Cannabis and schizophrenia

Despite the complexity, the authors argue against the notion that cannabis use by itself causes schizophrenia, citing stable rates of schizophrenia over the past 70 years despite a significant increase in cannabis use. However, they emphasize the potential public health issue of cannabis precipitating the onset of schizophrenia earlier in vulnerable individuals, leading to worse outcomes.

CBD's Role

Evidence suggests CBD, a cannabinoid, may have mild antipsychotic activity, potentially reducing the risk of triggering psychosis. This introduces a potential counterbalancing factor and raises the possibility of a more nuanced understanding of cannabis components.

Caution in Usage

Individuals with personal or familial histories of psychosis are advised to exercise caution, especially with high-THC cannabis products.

Regulation Concerns

Lack of FDA regulation for CBD products underscores the importance of purchasing from reputable sources.


As society grapples with the normalization and acceptance of cannabis, the authors stress the importance of understanding both the benefits and risks associated with its use. Encouraging responsible consumption, especially among teens and young adults with risk factors for psychosis, is paramount. While refraining from definitively asserting that cannabis causes psychosis, the authors advocate for informed decision-making based on personal risk factors and a nuanced understanding of the relationship between marijuana and psychosis.