Review of ‘Tell Your Children’ by Alex Berenson
Sharif B. Mohr, M.P.H., Ph.D.
Drug Free America Foundation


Tell Your Children is a well-written, well-researched, and easy to read book that outlines the relationship between marijuana use, mental illness, and violence. Berenson marshals the evidence and lays out his case in a compelling manner that is largely grounded in science yet remains accessible to the lay reader. As such, this book is a must-read for young people and parents alike, as well as for state legislators grappling with the issue of marijuana legalization.

Berenson starts us on our journey by providing a comprehensive overview of the history of marijuana use and its association with violence and mental illness by examining the first published reports of marijuana-related psychosis dating back to British India and early 20th century Mexico. He completes his historical treatise by describing the evolution of the definition and understanding of schizophrenia over the past 200 years.

Marijuana is somewhat unique among illicit drugs in that it is the only one to spawn a large and vocal lobby that has championed the cause of legalization since the 1970’s. In his review of the history of marijuana regulation in the USA, Berenson draws a disturbingly accurate parallel between the legalization movement and a religious cult—a comparison that would ordinarily be humorous if not for the high stakes involved. The legalization movement, like any religious cult, has its own doctrine and mantras grounded in blind belief rather than science (e.g. marijuana is completely harmless; marijuana is medicine etc). Indeed the legalization cult has its own holy day (4/20) and Mecca (Northern CA). This modern-day flat earth society has lost all semblance of objectivity on the issue, which as a scientist, I find to be the most disturbing aspect of this movement.

The next part of the book is where we get into the real meat of things when the scientific evidence of a causal relationship between marijuana use and mental illness is presented. Any single piece of evidence in isolation is not sufficient to prove causation and Berenson does an impressive job of presenting multiple lines of evidence from epidemiologic and laboratory studies that converge on a causal relationship between marijuana use and psychosis. Our epidemiological journey begins with the landmark 1971 Dunedin study that followed approximately 1,000 subjects from childhood through adulthood and collected a wide array of data on behaviors and outcomes including drug use and mental health. Studies of this type are considered to be highly robust in their ability to assess causality. The interest the Dunedin study generated among mental health researchers led to another seminal study that would further confirm the link between marijuana and mental illness: Andreasson’s 1987 study of over 45,000 Swedish military recruits.

In biomedical research, when evaluating a potential causal relationship between an exposure and disease (ie marijuana use and mental illness), a set of criteria known as the A.B. Hill criteria are applied: Temporality; Strength of Association; Dose-response; Consistency; Biological plausibility; Consideration of alternative hypotheses, Experiment, Specificity, and Coherence. To put it briefly, if an association satisfies a majority of these criteria, it may be considered causal. On a whole, the evidence Berenson lays out, based 50 years of peer-reviewed research, satisfies at least seven of the nine A.B. Hill Criteria. To put that into perspective, the association between cigarette smoking and lung cancer satisfies eight out of the nine criteria.

Berenson also makes note of how Britain’s ability to track drug use and mental health outcomes enabled British researchers to identify the link between schizophrenia and marijuana use decades ago, which ultimately shaped the downward trajectory of marijuana use in Britain. As Berenson points out, American adults in 2016 were much more likely to have used marijuana in the past month than British adults were to have used in the past year. This highlights the need in the USA for a comprehensive database that tracks mental illness. These databases, which made studies such as Andreasson’s possible, are essential to public health research efforts. Currently, American biomedical research efforts are largely devoted toward treating disease as opposed to preventing it.

The book is at its best when Berenson presents evidence from observational studies of individuals rather than ecological data or anecdotal case reports (although these certainly made for interesting reading). The weakest link in the chain of Berenson’s argument is the correlation of marijuana use with violence at the state-level using ecological data. He cites a rise in murders and violent crimes in WA since legalization of recreational marijuana in 2012 as evidence for this hypothesis. Ecological studies are subject to the ecological fallacy (attributing group characteristics to individuals). Thus, in epidemiological research, such studies cannot be used to infer causation. They are merely a starting point for formulating a hypothesis. Moreover, the increase in the murder rate in WA over the time period in question did not reach statistical significance (p=0.06) by Berenson’s own admission. As a researcher, I think this chapter would have been more appropriately placed nearer the beginning of the book since it provided the weakest evidence. My only other critique is the lack of a bibliography for the numerous studies he cited. Perhaps a bibliography is not appropriate for this type of writing but it could be included as an appendix. This would strengthen the overall scientific merit of the book while empowering more inquisitive readers with the option to read the original studies for themselves.

Those in favor of marijuana legalization will no doubt accuse the author of systematic bias by cherry-picking studies that support his argument. In reality, the entire metaphorical tree has been picked. The National Academy of Sciences, the most highly regarded group of scientists in the United States, released a report in 2017 based on an exhaustive review of all known research on marijuana. Their unequivocal conclusion is that cannabis use increases risk of developing schizophrenia and other psychoses. I also performed an extensive search of the literature from the time the NAS report was released through February 2019 and found that nearly every study on this topic, without exception, found an association between marijuana and schizophrenia and other psychoses.

We need more books of this type to help slow, if not stop, the legalization train in its tracks. The genie may already be out of the bottle but the evidence that Berenson has laid out will stand as a bulwark against the rising tide of legalization threatening to sweep across our nation much to the detriment of our most precious resource—the minds and futures of our young people.