The North American Prodrome Longitudinal Study (NAPLS) is a consortium of eight programs focusing on the psychosis prodrome. Funded by the National Institute of Mental Health (NIMH), the sites are located at Emory University, Harvard University, University of Calgary, UCLA, UCSD, University of North Carolina Chapel Hill, Yale University, and Zucker Hillside Hospital. Although the programs initially developed independently, they previously collaborated to combine their historical datasets and to produce a series of analyses on predictors of psychosis in one of the largest samples of longitudinally followed prodromal subjects worldwide. This led to the development of a five year prospective study "Predictors and Mechanisms of Conversion to Psychosis", (also known as NAPLS-2) with three major aims: (1) to prospectively test the prediction algorithm developed in NAPLS-1, (2) to investigate the neuroanatomical, neurophysiological, neurocognitive, and neurohormonal factors that may contribute to the development of psychosis, and (3) to develop a repository of DNA, RNA, and plasma from participants meeting diagnostic criteria for a clinical high risk (CHR) state and from demographically similar healthy subjects. Funded by NIMH in 2008, NAPLS-2 will generate the largest CHR for psychosis sample with 720 CHR and 240 healthy comparison subjects, and thus will provide statistical power and scientific scope that cannot be duplicated by any single site study. This paper describes the overall methodology of the NAPLS-2 project and reports on the ascertainment and demographics at the midway point of the study with (360 CHR) and 180 controls.
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