Recognizing and treating physical abuse in the adolescent is by far the most difficult. By now the teen is an expert at hiding bruises. Instead, teachers and health care professionals should be wary of exaggerated responses to being touched, provocative actions, extreme aggressive-ness or withdrawal, assaulting behavior, fear of adults, self-destruction, inability to form good peer relationships, alertness to danger, and/or frequent mood swings. Detection is exacerbated by the fact that all teenagers exhibit some of these signs at one time or another.
Abused teens do not evoke as much sympathy as younger victims, for society assumes that they are old enough to protect themselves or seek help on their own. In truth, all teenagers need adult guidance. The behavior that the abused adolescent often engages in—delinquency, running away, and failure in school—usually evokes anger in adults but should be recognized as symptoms of underlying problems. The abused teen is often resistant to therapy, which may take the form of individual psychotherapy, group therapy, or residential treatment.
While reporting child abuse is essential, false accusations can also cause great harm. It is a good idea for anyone who suspects that a child is being physically abused to seek confirmation from another adult, preferably a non-relative but one who is familiar with the family. If the second observer concurs, the local child protective services agency should be contacted. The agency has the authority to verify reports of child abuse and make decisions about protection and intervention.
Taken from : The Gale Encyclopedia Of Psychology 2ND Edition - Bonnie Strickland


