Doctors who watch for warning signs can often predict whether a teenager will develop schizophrenia or another psychotic illness, researchers in a government study reported yesterday.
Teens who spend excessive time alone doing nothing, withdraw socially or who begin thinking that people are following them have a 35 percent risk of progressing to psychosis within 2 1/2 years, the researchers said. But the odds rise steeply - as high as 80 percent - for youths who display combinations of symptoms.
No treatments can stave off or prevent a full-blown psychotic illness. But doctors who recognize early signs can monitor symptoms and offer help before the illness has spun out of control.
"Outcomes are much better for people who are treated as close to the onset of psychosis as possible," said Dr. Robert Heinssen, deputy director of intervention research at the National Institute of Mental Health and a collaborator on the study.
Schizophrenia, one of the most disabling psychotic illnesses, strikes about 1.1 percent of people 18 years or older. It may cause them to hear imaginary voices or believe others are following or plotting against them or wiring their thoughts.
The condition often strikes people in their late teens or early twenties, though studies have identified behaviors that can foreshadow the illness. But people at that point are still rational enough to see the error of their thoughts or to be talked out of them, Heinssen said.
"They have the ability to self-evaluate, to self-monitor and self-correct," Heinssen said. Once they cross a threshold into psychosis, they can no longer do that.
Calculating risk is fairly complicated, taking into account not only symptoms but their severity on a scoring system. But examples of teens with a 35 percent chance include those who have "unusual thoughts," such as a belief that a news article about someone else actually concerns them.
Also in the 35 percent group are people who see "fleeting images" in their peripheral vision or hear imaginary voices. Teens with a family history of psychosis combined with social withdrawal or a recent drop in grades also fall in this group.
The risk rises for teens with layered symptoms. Teens have an 80 percent chance, for instance, if they have a genetic risk, have trouble functioning, harbor unusual thoughts and are becoming socially withdrawn.
Heinssen said there is no evidence that giving teens anti-psychotic drugs before the illness is full blown does any good.
Dr. William T. Carpenter, director of the University of Maryland's Psychiatric Research Center, said the risk factors may actually be "minor" symptoms of psychosis. Some people begin to lose IQ points and become socially withdrawn by puberty, problems that may not be taken seriously until the person becomes disabled.
Early help won't stop the disease or lessen its severity, Carpenter said, but it can help some graduate from high school and maintain family relationships.
Also, he stressed, psychosis can develop in some young adults who never exhibited early signs.
Dr. J. Raymond DePaulo Jr., director of psychiatry at the Johns Hopkins School of Medicine, said the "checklist" may be of limited value to some parents.
"A worst-case scenario would be that a conscientious but statistically naive parent might now think that seeing any of these things means that their child is moving closer and closer to becoming schizophrenic," he said.