@article{c57f2313afd84adeaa0d01461fa41308,
title = "Factor analysis of the Scale of Prodromal Symptoms: data from the Early Detection and Intervention for the Prevention of Psychosis Program",
abstract = "Aim: The Scale of Prodromal Symptoms (SOPS) was developed to identify individuals experiencing early signs of psychosis, a critical first step towards early intervention. Preliminary dimension reduction analyses suggested that psychosis-risk symptoms may deviate from the traditional symptom structure of schizophrenia, but findings have been inconsistent. This study investigated the phenomenology of psychosis risk symptoms in a large sample from a multi-site, national study using rigorous factor analysis procedure. Methods: Participants were 334 help-seeking youth (age: 17.0 ± 3.3) from the Early Detection and Intervention for the Prevention of Psychosis Program, consisting of 203 participants at clinically higher risk (sum of P scores ≥ 7), 87 with clinically lower risk (sum of P scores < 7) and 44 in very early first-episode psychosis (<30 days of positive symptoms). Baseline SOPS data were subjected to principal axis factoring (PAF), estimating factors based on shared variance, with Oblimin rotation. Results: PAF yielded four latent factors explaining 36.1% of total variance: positive symptoms; distress; negative symptoms; and deteriorated thought process. They showed reasonable internal consistency and good convergence validity, and were not orthogonal. Conclusions: The empirical factors of the SOPS showed similarities and notable differences compared with the existing SOPS structure. Regrouping the symptoms based on the empirical symptom dimensions may improve the diagnostic validity of the SOPS. Relative prominence of the factors and symptom frequency support early identification strategies focusing on positive symptoms and distress. Future investigation of long-term functional implications of these symptom factors may further inform intervention strategies.",
keywords = "factor analysis, prodrome, psychosis, schizophrenia, ultra high risk",
author = "Tso, {Ivy F.} and Taylor, {Stephan F.} and Grove, {Tyler B.} and Tara Niendam and Steven Adelsheim and Andrea Auther and Barbara Cornblatt and Carter, {Cameron S.} and Roderick Calkins and Ragland, {J. Daniel} and Tamara Sale and McFarlane, {William R.}",
note = "Funding Information: This work was supported by the Robert Wood Johnson Foundation (grant number #67525 to WRM), with additional institutional support from the Maine Medical Center Research Institute and the State of Maine. Dr. Tso receives funding from the National Institutes of Health (5KL2TR000434-08). Dr. Taylor receives funding from the Boledovich Schizophrenia Fund, the Drake Family Fund, and the National Institute of Mental Health (R21 MH101676). Dr. Cornblatt receives funding from the National Institute of Mental Health (R01 MH061523; U01 MH081857). Dr. Ragland receives funding from the National Institute of Mental Health (R01 MH084895). The funders of the study had no role in the study implementation, data collection, analysis, interpretation or reporting of the results in this article. The authors are solely responsible for its contents. Funding Information: This work was supported by the Robert Wood Johnson Foundation (grant number #67525 to WRM), with additional institutional support from the Maine Medical Center Research Institute and the State of Maine. Dr. Tso receives funding from the National Institutes of Health (5KL2TR000434-08). Dr. Taylor receives funding from the Boledovich Schizophrenia Fund, the Drake Family Fund, and the National Institute of Mental Health (R21 MH101676). Dr. Cornblatt receives funding from the National Institute of Mental Health (R01 MH061523; U01 MH081857). Dr. Ragland receives funding from the National Institute of Mental Health (R01 MH084895). The funders of the study had no role in the study implementation, data collection, analysis, interpretation or reporting of the results in this article. The authors are solely responsible for its contents. Dr. McFarlane discloses that he provides on-request training and consulting to public and not-for-profit agencies implementing the clinical services being tested in EDIPPP. Dr. Carter discloses that he has served as a consultant for Merck, Lilly, Pfizer and Servier and has received research funding from Glaxo Smith Kline. Dr. Taylor discloses receiving research support from St. Jude Medical and Neuronetics. No other author discloses competing interests. The authors wish to acknowledge the contributions from the staff and clinicians of the participating sites of the EDIPPP, and the participants who volunteered for the study. An earlier version of this study was presented at the Society of Biological Psychiatry Annual Meeting; San Francisco, California; 17 May 2013. Publisher Copyright: {\textcopyright} 2014 Wiley Publishing Asia Pty Ltd",
year = "2017",
month = feb,
day = "1",
doi = "10.1111/eip.12209",
language = "English (US)",
volume = "11",
pages = "14--22",
journal = "Early Intervention in Psychiatry",
issn = "1751-7885",
publisher = "Wiley-Blackwell",
number = "1",
}