Many doctors and therapists use unproven approaches such as drugs, art or play therapy on children suffering trauma when old-fashioned talk therapy has been shown to work, a report released on Tuesday said.

A review of a dozen different studies showed no evidence that alternative therapies helped children traumatized by violence or abuse, even though more than 75 percent of U.S. mental health professionals who treat children and teens with post traumatic stress disorder may use them.

But cognitive therapy -- a type of talk therapy aimed at changing negative thoughts -- does work, the group at the U.S. Centers for Disease Control and Prevention said.

"The good news is there is substantial research showing the effectiveness of group or individual cognitive behavioral therapy in treating children and teens experiencing the psychological effects of trauma," the CDC's Robert Hahn, who led the study, said in a statement.

"We hope these findings will encourage clinicians to use the therapies that are shown to be effective."

Children can be traumatized by many things including physical or sexual abuse, witnessing domestic violence, community violence or natural disasters.

"Childhood trauma is a widespread problem with both short- and long-term consequences," Hahn said.

"Many kids with symptoms of trauma go undiagnosed, which can lead to unhealthy behaviors in adulthood such as smoking and alcohol or drug abuse."

He said better screening is needed and urged therapists to use proven methods.

Cognitive therapy uses a variety of techniques, but always involves a trained counselor and several sessions, to change a person's thoughts and beliefs.

Hahn's task force reviewed studies evaluating play therapy, art therapy, the use of drugs and psychological debriefing.

Play therapy allows a child to use toys or imagination to "express experiences, thoughts, feelings, and desires that might be more threatening if addressed directly," according to the report.

"Proponents of art therapy argue that trauma is stored in the memory as an image; therefore, expressive art techniques are an effective method for processing and resolving traumatic issues," it adds.

Psychological debriefing, also known as critical incident stress management, is a group meeting within days of an event to allow people to share thoughts and feelings.

None has been shown to work for children with post traumatic stress disorder, the CDC team reported in the American Journal of Preventive Medicine.

(Reporting by Maggie Fox, editing by Alan Elsner and Will Dunham)