WHY IT MATTERS: Parents, pediatricians, and young people themselves need to understand that the risk calculus for cannabis is not the same at 15 as it is at 35, and that psychosis and bipolar disorder are not rare or abstract outcomes but life-altering diagnoses with serious long-term consequences. CLINICAL OVERVIEW: The relationship between adolescent cannabis use and psychiatric outcomes has been a subject of serious scientific inquiry for decades, with converging evidence suggesting that exposure during neurodevelopmental windows carries meaningfully different risks than adult-onset use. The adolescent brain, particularly the prefrontal cortex and limbic system, undergoes significant synaptic pruning and maturation through the mid-twenties, and the endocannabinoid system plays a direct regulatory role in that process.