New cannabis findings for adolescents

Teen cannabis use is being linked to slower gains in memory, attention and thinking speed during the years when those skills usually sharpen fastest. (today.ucsd.edu) Researchers at the University of California, San Diego reported April 20 that adolescents who began using cannabis showed “restricted growth over time” across memory, attention, language and processing speed in the Adolescent Brain Cognitive Development study. The paper was published the same day in *Neuropsychopharmacology*. (today.ucsd.edu; nature.com) The analysis followed 11,036 children from ages 9 to 10 through ages 16 to 17, and it did not rely only on self-reports. The team also used hair, urine, breath and oral-fluid testing to identify cannabis exposure. (today.ucsd.edu; nature.com) Cognitive development is the brain’s normal climb in skills like recall, focus and mental speed as children move through middle school and high school. In this study, some cannabis-using teens started out performing about as well as, or slightly better than, peers in late childhood, then improved more slowly after use began. (nature.com; today.ucsd.edu) The paper also separated two cannabis compounds in a smaller subgroup with repeated hair testing. Teens with tetrahydrocannabinol, or THC, exposure showed worse episodic memory over time than controls, while the cannabidiol, or CBD, group did not show the same pattern. (nature.com; today.ucsd.edu) The authors adjusted for a long list of factors that can muddy this kind of research, including family background, prenatal substance exposure, early mental-health symptoms, family history of substance use disorder and other substance use. The study still found altered cognitive trajectories tied to cannabis onset. (nature.com) Federal health guidance has long warned that cannabis can affect the parts of the brain involved in memory, learning, attention, decision-making and reaction time, especially before age 18. The Centers for Disease Control and Prevention says teen cannabis use is also linked to problems with school and social life. (cdc.gov; cdc.gov) The new findings land in a period when cannabis laws have loosened in many states, THC potency has increased and perceived risk has fallen, according to the paper’s introduction. The researchers said continued follow-up into young adulthood will test how timing of first use shapes later outcomes. (nature.com) Lead author Natasha Wade said the differences “may seem small at first” but can accumulate in learning, memory and everyday functioning. The next readout from this cohort will show whether those flatter gains persist after adolescence ends. (today.ucsd.edu)