Psychologists discussed the possible public health implications of marijuana legalization – including the negative effects on the brains of teenagers and young adults who engage in frequent marijuana use – during a symposium at the American Psychological Association’s 122nd Annual Convention.
Krista Lisdahl, Ph.D, director of the brain imaging and neuropsychology lab at University of Wisconsin-Milwaukee, says that regular cannabis use – considered once-a-week – is not safe and may result in addiction and neurocognitive damage, especially in youth. Lisdahl says marijuana use is increasing among young people, and that brain imaging studies of regular marijuana users have shown significant changes in their brain structure, particularly among adolescents.
When considering legalization, policymakers need to address ways to prevent easy access to marijuana, provide additional treatment funding for adolescent and young adult users and consider regulating levels of tetrahydrocannabinol (THC), the major psychoactive chemical in marijuana, in order to reduce potential neurocognitive effects, she says.
In recent years, some legalized forms of marijuana have higher levels of THC than other strains, says presenter Alan J. Budney, Ph.D., professor at the Geisel School of Medicine at Dartmouth, DH Addiction Treatment and Research Program in New Hampshire.
The implications of the higher dosage aren’t clear. “Most of what we know from research so far about marijuana and prevalence of developing major problems all comes from data in the past,” Budney says. “It’s only recently that the percentage of THC in street marijuana and in dispensaries is going up and up and up. There is a more potent product on the street.”
Additionally, edibles like cookies and gummies can be laced at very high dosages, he says. “We know very little about high-dose marijuana; all of the studies are based on lower doses,” Budney says. “It’s a much different product.”
“Unless you are legalizing the THC level, people are going to make products that are more addictive.”
Research suggests that high-dose, high-frequency use of marijuana can lead to earlier onset of mental illness, Budney says.
By making marijuana more accessible and acceptable, use among youth will likely continue to increase. “What will happen with legalization, we’re not sure, but it will certainly increase access and with the advertisement, probably more people will try marijuana,” he says.
Budney says teens are particularly at risk for developing problems from marijuana use. “The younger you start, the higher probability that you’ll develop a problem.”
Even if the age for legalization is 21 and over, “when things get legalized, there’s a trickle-down effect,” Budney says and young people may be able to more easily access it.
Also, “parents may be more lenient about marijuana because it is legal,” he adds.
“We now know alcohol is plenty harmful and it’s legal and cigarettes. Just because it’s legal doesn’t mean it’s not harmful. But that’s going to be the mindset for a while.”
In addition to regulation, much work needs to be done in the areas of treatment and prevention, Budney says, noting that interventions have efficacy, but are fairly weak. “Most people, when they come to treatment, don’t necessarily do that well. People develop a real problem with it and have a very hard time quitting, just like with cigarettes, alcohol or cocaine. Once you develop the problem, it’s not really easy to treat.”
By Pamela Berard