With many states legalizing marijuana, the U.S. surgeon general issued a rare advisory, warning adolescents against using the substance because their brains are still developing until age 25. NBC senior national correspondent Kate Snow joins TODAY for an in-depth look at the issue. » Subscribe to TODAY: http://on.today.com/SubscribeToTODAY » Watch the latest from TODAY: http://bit.ly/LatestTODAY About: TODAY brings you the latest headlines and expert tips on money, health and parenting. We wake up every morning to give you and your family all you need to start your day. If it matters to you, it matters to us. We are in the people business. Subscribe to our channel for exclusive TODAY archival footage & our original web series. Connect with TODAY Online! Visit TODAY's Website: http://on.today.com/ReadTODAY Find TODAY on Facebook: http://on.today.com/LikeTODAY Follow TODAY on Twitter: http://on.today.com/FollowTODAY Follow TODAY on Instagram: http://on.today.com/InstaTODAY Follow TODAY on Pinterest: http://on.today.com/PinTODAY #Marijuana #LegalizingMarijuana #TodayShow Don’t Use Marijuana Before Age 25, Surgeon General Warns | TODAY