• DOI:10.1001/archgenpsychiatry.2007.3
• Corpus ID: 13960664

Prediction of psychosis in youth at high clinical risk: a multisite longitudinal study in North America.

@article{Cannon2008PredictionOP,
  title={Prediction of psychosis in youth at high clinical risk: a multisite longitudinal study in North America.},
  author={Tyrone D. Cannon and Kristin S. Cadenhead and Barbara A. Cornblatt and Scott W. Woods and Jean M. Addington and Elaine F. Walker and Larry J. Seidman and Diana O. Perkins and Ming T. Tsuang and Thomas H. McGlashan and Robert K. Heinssen},
  journal={Archives of general psychiatry},
  year={2008},
  volume={65 1},
  pages={
          28-37
        }
}

• Tyrone D. Cannon, K. Cadenhead, +8 authors R. Heinssen
• Published 2008
• Psychology, Medicine
• Archives of general psychiatry

CONTEXT
Early detection and prospective evaluation of individuals who will develop schizophrenia or other psychotic disorders are critical to efforts to isolate mechanisms underlying psychosis onset and to the testing of preventive interventions, but existing risk prediction approaches have achieved only modest predictive accuracy.

OBJECTIVES
To determine the risk of conversion to psychosis and to evaluate a set of prediction algorithms maximizing positive predictive power in a clinical high-risk sample.

DESIGN, SETTING, AND PARTICIPANTS
Longitudinal study with a 2 1/2-year follow-up of 291 prospectively identified treatment-seeking patients meeting Structured Interview for Prodromal Syndromes criteria. The patients were recruited and underwent evaluation across 8 clinical research centers as part of the North American Prodrome Longitudinal Study.

MAIN OUTCOME MEASURE
Time to conversion to a fully psychotic form of mental illness.

RESULTS
The risk of conversion to psychosis was 35%, with a decelerating rate of transition during the 2 1/2-year follow-up. Five features assessed at baseline contributed uniquely to the prediction of psychosis: a genetic risk for schizophrenia with recent deterioration in functioning, higher levels of unusual thought content, higher levels of suspicion/paranoia, greater social impairment, and a history of substance abuse. Prediction algorithms combining 2 or 3 of these variables resulted in dramatic increases in positive predictive power (ie, 68%-80%) compared with the prodromal criteria alone.

CONCLUSIONS
These findings demonstrate that prospective ascertainment of individuals at risk for psychosis is feasible, with a level of predictive accuracy comparable to that in other areas of preventive medicine. They provide a benchmark for the rate and shape of the psychosis risk function against which standardized preventive intervention programs can be compared.