A new UC San Diego study strengthens the growing body of evidence that marijuana use impacts adolescent brain development.
Researchers observed slower gains in cognitive tests that measured memory, focus and thinking speed among middle and high school-age kids who used cannabis when compared to those who abstained.
Scheduled for publication online today in the journal Neuropsychopharmacology, the study analyzes how 11,000 kids across the nation enrolled in the Adolescent Brain Cognitive Development Study, a $440 million effort that the National Institutes of Health calls “the largest long-term study of brain development and child health ever conducted in the United States.”
Annual testing started in 2016 when participants were 9 or 10 years old, finishing its initial decade-long collection period at 21 sites nationwide this fall. UCSD is the program’s nationwide coordinator and one of its most active hubs, with 740 local enrollees.
New JAMA study shines a light on cannabis use and mental health. This study found that adolescent cannabis use is associated with increased risk of psychiatric disorders in adolescence and young adulthood, highlighting the importance of early prevention efforts, effective public health messaging, and policy development to limit youth exposure as cannabis legalization expands.
The new HIDTA California Marijuana Impact Report is here. The report will be highlighted in a community briefing that will focus on the rising impact of marijuana on public health, including youth mental health, and its potential links to suicide. The data will show trends in cannabis-related hospitalizations, addiction, and psychosis—particularly among youth—this event aims to raise awareness and advocate for urgent prevention efforts.
Data highlights from the report:
In 2022, 43% of suicides among individuals 25 and under in San Diego County involved THC.
Emergency visits due to marijuana rose by 521% in California from 2008 to 2022.
Youth aged 12–17 accounted for nearly 38% of marijuana treatment admissions in 2023.
High-potency cannabis is increasingly linked to psychosis and cannabis use disorder.
CCR and CPHI offered technical assistance and media support for this event.
Now, researchers are coming to understand the hazards of vapes themselves. In a study from last month, for example, a team of scientists analyzed the mist from popular vapes and found such high levels of heavy metals that one researcher thought their machine had malfunctioned. Other studies have suggested that vaping can affect the heart, lungs and brain.
Data on the long-term health effects is limited, because vapes are relatively new and constantly evolving. Many people who use them are in their teens or 20s; it might take a while before further effects become apparent. Consumers also often use both cigarettes and vapes, which makes it difficult to isolate harms from vaping alone. Vaping is still less common than cigarette use among U.S. adults, 4.5 percent of whom said they vaped in2021. Nearly 8 percent of high school students reported vaping in the last month in a 2024 survey.
In this survey study of 7612 adolescents, frequent exposure to cannabis posts on social media broadly was associated with solo e-cigarette use, solo cannabis use, and dual use initiation a year later, whereas platform-specific exposure to e-cigarette posts on TikTok was associated with solo cannabis and dual use initiation. Exposure to e-cigarette and cannabis posts from microinfluencers was associated with past-month cannabis use, whereas exposure to e-cigarette posts from friends was associated with past-month dual use; exposure to friends’ cannabis posts was also associated with past-month cannabis and dual use.
Since exposure to e-cigarette or cannabis posts may contribute to adolescent e-cigarette, cannabis, or dual use, improvement of social media community guidelines and greater policy attention to co-use and marketing of e-cigarettes and cannabis may help prevent youth substance use.