Critics of his work say the author tossed aside the preponderance of known science to sell books.

But most of those critics have a financial stake in the pot game, Berenson said. A public policy change isn’t the best solution, he said, but educating people about the risks is vital.

“That sounds like a cop-out, but that’s the only really good answer,” he said.

Berenson cited a new study published in The Lancet Psychiatry journal that found people who use cannabis daily are three times more likely than non-users to eventually have a psychotic episode. Those who use high-potency pot are four times more likely, and those who starting getting high before age 15 carry even more risk, the study found.

“This is more evidence that the link between cannabis and psychosis matters,” Krista M. Lisdahl, a clinical neuropsychologist at the University of Wisconsin in Milwaukee, told National Public Radio.

Berenson’s book makes the case that not enough has been done scientifically to explore whether pot poses serious mental health risks for its users, especially younger ones.

The advice he would give parents is to keep kids off pot as long as possible. “Wait, wait, wait,” Berenson said. “This is not a safe substitute for alcohol.”

With a couple of exceptions (nausea and some effects if multiple sclerosis), Berenson disputes experts who say marijuana has medicinal value. To broadly prescribe it for pain is a fallacy with little backing, other than people believing it works, he said.

He said the studies that show cannabis helps with pain are funded by the industry, and the effects are marginal.

The author, a father of two and husband of a forensic psychiatrist, said the data tells him that pot could lead to psychosis and schizophrenia for heavy users.

Yet most people have embraced marijuana as safe, if not medicinal, Berenson said.

“I was a pretty good investigative reporter, because I often saw the way companies would deceive, especially when there’s money on the line,” he said. “I mention that because I think this story of cannabis legalization is a story of deception, but it’s also sort of self-deception.”

At the Arapahoe High School talk Tuesday night in Centennial, Kent Osborn recalled how his son Tom was caught driving while impaired on pot.

After he dropped out of the University of Utah, Tom worked in a movie theater at The Streets at SouthGlenn in Centennial and stayed clean for two years while he was on probation, Osborn said.