SCI AM | M Kulyk/Science Photo Library/Getty
For decades, Americans have been told a simple story about addiction: taking drugs damages the brain—and the earlier in life children start using substances, the more likely they are to progress through a “gateway” from milder ones such as marijuana to more dangerous drugs such as opioids. Indeed, those who start using at younger ages are much more likely to become addicted. But a recent study, part of an ongoing project to scan the brains of 10,000 kids as they move through childhood into adulthood, complicates the picture.