A massive study tracking over 460,000 teens found that cannabis use during adolescence doubled the risk of psychotic and bipolar disorders, underscoring why age restrictions and youth prevention are critical. Neuroscience News deep-dive into the WSU/Calgary PNAS study on cannabis-induced appetite. THC activates CB1 receptors in the hypothalamus to override natural satiety signals, creating a feeling of starvation even in recently fed subjects.