Jenna interviews Dr. Lynn Silver, a pediatrician and co-author of a new large California study examining how adolescent cannabis use relates to later mental health outcomes. Using Kaiser Permanente screening data from 463,000 teens ages 13–17 and following them up to seven years (or until age 25), the study compared youth who reported past-year cannabis use with those who did not, excluding those with prior diagnoses. Teens who reported cannabis use were about twice as likely to later be diagnosed with psychosis/schizophrenia and bipolar disorder, about one-third more likely to develop depression, and about one-quarter more likely to develop anxiety. The discussion also covers barriers to cannabis research, rising THC potency and new products, how genetics and environmental triggers may interact, and why decriminalization differs from for-profit legalization and youth marketing.