Today’s pot is typically four times stronger than the marijuana of just a couple of decades ago.

That’s timely to note in the current push to legalize the drug, because much of the research showing marijuana has only modest health effects on adults is based on weaker strains that have been largely bred out of the marketplace.

“We’re all riding this green rush right now,” said Staci Gruber, a psychiatry professor at Harvard Medical School who studies the effects of marijuana use on the brain. “But there’s still so much that we don’t know.”

The Cannifornian is publishing an occasional series that surveys current research and interviews experts on common questions about marijuana use: the potential health risks, issues of government regulation and the experience of states where recreational use of cannabis is legal.

Q. Is marijuana riskier now than it used to be?

A. Updated research is needed, experts say, with pot potencies and products constantly evolving.

Through the 1990s, marijuana typically had about 4 percent THC, the main compound that makes consumers high, according to Madeline Meier, a psychologist at Arizona State University. Thanks to cultivators who’ve crossbred strains to boost potency, today’s cannabis commonly has 15 percent, 20 percent, even 30 percent THC. And concentrates — such as waxes, tinctures and oils — can reach 60 percent or 80 percent.

Such potencies can lead to negative experiences for baby boomers who haven’t lit up in decades or for inexperienced consumers who don’t know how to properly dose their intake, Gruber said. There’s also concern among experts that increasingly potent products heighten health risks.

Hope by the Sea treatment center in San Juan Capistrano has seen a slight uptick in patients seeking treatment for marijuana abuse, according to admissions coordinator Corey Richman. Anecdotally, he said, those patients seem to exhibit more serious symptoms of dependency, such as hoarding supplies rather than embracing the sharing, “puff, puff, pass” culture of marijuana’s low-THC days.

Requiring products to be tested and clearly labeled for potency can help consumers make more informed decisions, Gruber said.

California is developing regulations on testing, labeling and packaging for medical marijuana that will carry forward for recreational pot.

Colorado considered an initiative for the November ballot that would have gone a step further, capping THC at 16 percent and requiring edibles to be sold in low-dose, single-serving packages. But backers dropped the effort amid fierce pushback from those who said such limits violated rights now incorporated in the state constitution and would have wiped out 80 percent of the legal pot market.

Q. Is pot a gateway drug?

A. The theory that cannabis use leads to harder drugs — advanced by some politicians and public-safety officials — remains divisive in the medical community, even as it has been discounted by federal medical researchers.

It’s a fact that surveys show the majority of people who try substances such as cocaine or heroin say they first used pot.

The same surveys find most people who try marijuana first used cigarettes and alcohol. And national drug-use data indicate the majority of people who try marijuana never move on to other more powerful, addictive drugs.

Nearly 8.5 percent of the population said they’d used marijuana in the past month, according to the latest National Survey on Drug Use and Health. Just 2.5 percent said they’d used the next most common family of abused drugs: prescription medications. And fewer than 1 percent had tried drugs such as cocaine, LSD or heroin.

Marijuana use is also increasing, the national survey shows. With the exception of a surge of heroin use in recent years, consumption of other drugs is flat or declining.

Some experiments on rats have indicated that marijuana causes a change in brain circuitry that triggers the use of harder drugs. If that’s true, Gruber said, researchers would expect to see a higher percentage of people making the jump to more powerful substances.

What correlations may exist appear to be tied more to social factors, such as peer pressure and family environment, than physiological ones, experts say.

People who want the mind-altering effect of harder drugs might start with pot because it’s easier to get, for example. Legalization advocates argue that allowing recreational marijuana use would reduce consumer migration to more dangerous narcotics by curbing interactions with street dealers, who have a financial incentive to push harder drugs.

A study from the federal Institute of Medicine sums it up this way: “Because underage smoking and alcohol use typically precede marijuana use, marijuana is not the most common, and is rarely the first, ‘gateway’ to illicit drug use. There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.”

Q. Can cannabis trigger mental health problems?

A. The answer’s not simple. Recent studies have concluded that cannabis can both intensify and relieve various mental health conditions.

“For people with a predisposition, marijuana can exacerbate certain symptoms,” Gruber said. “But you also have the flip side: There are people with psychological disorders who find some therapeutic benefits from marijuana use.”

Look, for example, at anxiety.

Anxiety is one of the most common conditions users say prompts them to turn to medical marijuana. And a study published in February in the journal JAMA Psychiatry that tracked users over time found no link between marijuana consumption and an increase in mood disorders.

But some people do experience temporary anxiety or paranoia when they use marijuana, particularly when it has a high concentration of THC. In rare cases, Hoag Hospital’s Alexander said, potent pot can trigger anxiety that escalates to psychotic episodes.

For people with a family history or symptoms of conditions such as schizophrenia, a 2014 study published in the journal Frontiers in Psychiatry suggests heavy cannabis use might trigger or worsen the illness.

At the same time, Gruber’s research shows promise that medical marijuana can ease symptoms of bipolar, post-traumatic stress and attention deficit disorders. Notably, she said, patients showing success are using products that are low in THC and higher in CBD, a compound believed responsible for much of marijuana’s medical benefits without the mind-altering effects.

“So much depends on exactly what products people are using,” she said, adding that consumers respond differently to various strains, doses and methods of ingestion. “It can be a very personalized experience.”

Alexander recommends people seeking to treat a mental health condition with cannabis do so under the guidance of a knowledgeable doctor.

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