By By Mike Stobbe The Associated Press NEW YORK (AP) - After years of decline, teen deaths from drug overdoses have inched up, a new U.S. government report shows. The drop in teen deaths had been a rare bright spot in the opioid epidemic that has seen adult overdose deaths surge year after year - fueled by abuse of prescription painkillers, heroin and newer drugs like fentanyl. "This is a warning sign that we need to keep paying attention to what's happening with young people," said Katherine Keyes, a Columbia University expert on drug abuse issues who wasn't part of the study. It's not clear why teen overdose deaths increased in 2015 or whether the trend will continue, said lead researcher Sally Curtin of the U.S.