A major new study tracking thousands of American children over several years is raising concerns about how cannabis use may affect developing brains. Researchers at the University of California San Diego followed more than 11,000 participants from late childhood into their teenage years, making it the largest long-term study of its kind in the U.S. The findings suggest that teens who begin using cannabis show slower progress in key cognitive areas compared to their peers . According to the research, differences emerged across multiple skills, including memory, attention, language, and processing speed. While many of the teens started out on similar footing, those who reported cannabis use over time didn’t improve at the same pace as those who abstained. “Adolescence is a critical time for brain development, and what we’re seeing is that teens who start using cannabis aren’t improving at the same rate as their peers,” said lead author Natasha Wade, an assistant professor of psychiatry at UC San Diego.…