Parents' complaints about sudden mood swings of teenagers are common, but new research shows that children who experience early-life stresses such as abuse, neglect, or loss of a parent have an increased risk in adolescence of behavioral and emotional disorders. The research, conducted on rhesus macaque monkeys at the Oregon National Primate Research Center at Oregon Health & Science University and at the University of Pittsburgh, suggests that adolescents who have been exposed to early-life stress have a greater incidence of developing an attachment disorder, attention deficit hyperactivity disorder, conduct disorder, anxiety, depression, suicide, drug abuse, and post-traumatic stress disorder.