The presence of a risk factor or combination of risk factors can identify a large proportion of youth who will develop psychosis before illness becomes full-blown, according to an article in the January issue of Archives of General Psychiatry.

Researchers evaluated 291 prospectively identified treatment-seeking patients (median age, 16 years) who met Structured Interview for Prodromal Syndromes criteria.

Risk factors included deterioration in social functioning, family history of psychosis combined with recent decline in general function such as school performance, increase in unusual thoughts such as perception that strangers' conversations are about the individual, increase in suspicion/paranoia, and past or current drug abuse.

A total of 35 percent of participants with at least one risk factor developed a psychotic illness within the 30-month study timeframe. However, when researchers broke the data down further, they found that youth who had two or three additional risk factors developed psychosis at a rate of 68 to 80 percent, depending on which risk factors were combined.

A separate group of 134 healthy people with no known risk factors for psychosis served as a control group. None of them developed a psychotic illness.

Researchers also found that the youth who progressed to a psychotic disorder tended to do so relatively quickly. Twenty-two percent developed psychosis within the first year of follow-up, an additional 11 percent by the end of the second year, and 3 percent more by two-and-a-half years.

The current study is the largest of its kind to be conducted to date. Knowing what these combinations are can help scientists predict who is likely to develop illnesses within two to three years with the same accuracy that other kinds of risk factors can predict major medical diseases such as diabetes.

Plans for studies to confirm the results, a necessary step before the findings can be considered for use with patients in health-care settings, are underway.

The research was funded primarily by the National Institute of Mental Health (NIMH), and was led by researchers Tyrone D. Cannon, PhD, of the University of California Los Angeles, and Robert Heinssen, PhD, of NIMH, with colleagues from seven other research facilities.

"When teens have a dive in grades or drop out of the school band, and it happens against a backdrop of family history of schizophrenia and recent troubling changes in perception - like hearing nondistinct buzzing or crackling sounds, or seeing fleeting images that disappear with a second glance - more often than not it indicates that psychosis is fairly imminent," Cannon said.

Research shows that intervention during the early stages of psychosis improves outcomes, but it is not yet clear if even earlier intervention, before a psychotic illness develops, is effective.

"Having this more accurate ability to measure who's likely to develop psychosis will be a great asset. Identifying young people in need of intervention is crucial, but the results of this research can help us do more than that. It can eventually help us determine the most effective time to intervene," said NIMH Director Thomas R. Insel, M.D.

"The message here is that once we identify people as being high risk, we have a very good chance of knowing whether or not they're likely to develop a serious mental disorder like schizophrenia and that, if they do, it will happen fairly quickly. That's such a critical window of opportunity for getting them the help they need," said Heinssen.

The investigators who conducted the study are part of a consortium of nine research centers, the North American Prodromal Longitudinal Study (NAPLS), whose goal is to improve the accuracy of predicting psychosis. The consortium is funded by NIMH, which also provides administrative leadership.