Marijuana use associated with worse school performance and emotional distress for teens

Using marijuana just once or twice a month was associated with worse school performance and emotional distress for teens, according to a large national study of adolescents led by Ryan Sultán, an assistant professor of clinical psychiatry at Columbia University Vagelos College of Physicians and Surgeons. The more frequently teens used cannabis, the more likely they were to report emotional distress and other social and academic problems. 

"While previous studies have focused on the effects of frequent cannabis use among teens, our study found that any amount of cannabis use at all may put kids at risk of falling behind in school, and the kids using most often may have the greatest risk," says Sultán, who studies adolescent substance use. "A few 'harmless' joints can snowball into real academic consequences. Teens using it regularly often struggle to focus, miss school, and may lose interest in their future plans." 

Shifting trends in teen drug use 

The new study arrives amid a national backdrop of shifting trends in teen drug use. While use of many substances is at record lows among US youths, cannabis remains an exception. About 1 in 5 high school students currently use cannabis, and approximately 6% of 12th graders use it daily – a rate that has increased in the past decade. 

"The real-world impact can be dramatic," Sultán says. "It's not uncommon for a young teen to smoke marijuana only a few times before showing signs of withdrawal and worsening mood." 

Scientists are especially concerned because today's cannabis products contain two to three times more THC (the ingredient that causes a high) than in the past, making them more potent. And previous studies have shown that using cannabis during adolescence, when the brainis still developing critical neural connections, may have lasting effects on cognitive functions that are critical to academic performance. "A teenager's brain is still developing the circuits for learning, self-control, and emotional regulation," says Tim Becker, a child & adolescen tpsychiatrist at Weill Cornell Medicine and study co-author. "Using cannabis, even casually, during these critical growth periods interferes with those processes and can derail normal development." 

Study details 

The new study analyzed data from a nationally representative survey of over 160,000 U.S. 8th, 10th, and 12th grade students conducted from 2018 to 2022. Over one-quarter of the respondents reported cannabis use; less than 20% reported monthly or less frequent use; and much smaller percentages said they used cannabis weekly or almost every day. 

In the study, adolescents who used cannabis once or twice a month reported higher rates of depression-like symptoms, anxiety, and impulsive behavior than those who abstained. Near-daily users were almost four times as likely to have poor grades and were frequentlydisengaged from school activities. These associations were even stronger for younger cannabis users. 

What should parents and caregivers do? 

Experts recommend having frank, nonjudgmental conversations with teens about cannabis early and often. 

"Make sure they understand that "natural" doesn't mean "safe," Sultán says. "Parents also need to keep an eye out for warning signs like declining grades, mood changes, or loss of interest in hobbies – and consider that cannabis could be a factor."