A total of 888 subjects enrolled in North American prodromal schizophrenia research projects between the years 1998 and 2005 are included in the baseline database. Among this group, 651 subjects have sufficient data for planned outcome analyses. The majority of subjects (n = 801) had been recruited into longitudinal assessment studies with naturalistic designs; approximately 10% (n = 87) had participated in medication trials, with random assignment to either placebo or active treatment. For the purpose of this article, the NAPLS sample is organized into 6 nonoverlapping groups that reflect varying degrees of psychosis vulnerability (see ). Group assignments are made on the basis of subjects' SIPS responses during the initial diagnostic interview, information about family history of psychotic disorders, and the presence or absence of Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) schizotypal personality disorder at the time of index evaluation.
Criteria for Subjects' Group Assignment
Individuals believed to be at heightened clinical risk for psychosis make up the largest subgroup in the database (n = 370). These were all help-seeking individuals who presented for evaluation and treatment at established clinical and psychiatric settings. The Criteria of Prodromal Syndromes (COPS; see ) describe 3 pathways to a SIPS prodromal syndrome diagnosis: (1) presence of attenuated positive symptoms such as perceptual abnormalities, suspiciousness, and unusual ideas (Attenuated Positive Symptom Syndrome [APSS]), (2) genetic risk for psychosis coupled with deterioration in global functioning (Genetic Risk and Deterioration Syndrome [GRDS]), and (3) intermittent psychotic symptoms that are recent, brief in duration, and not seriously disorganizing or dangerous (Brief Intermittent Psychotic Syndrome [BIPS]). Most subjects in the NAPLS clinical high-risk (CHR) group reported APSS only (349; 94.3%). BIPS and GRDS diagnoses were far less common (2.9 and 0.6%, respectively), and multiple prodromal diagnoses were equally rare (2.2%).
Other at risk groups include individuals with 1 or more first-degree relatives who are diagnosed with any form of psychotic illness (n = 65), persons who meet DSM-IV criteria for schizotypal personality disorder (n = 56), and patients with recently developed psychotic symptoms (n = 28). Additional comparison groups include help seekers who fail to meet criteria for elevated clinical risk by COPS (n = 174) and nonpsychiatric controls (NPCs) (n = 195). Because help seekers report a plethora of worrisome clinical symptoms, they are included to test the sensitivity and specificity of current prodromal diagnostic criteria. NPC subjects provide benchmark information regarding normal developmental processes in adolescents and young adults.
compares subjects in the 3 largest NAPLS subgroups on selected demographic, instrumental functioning, and diagnostic variables. The CHR and help-seeking control (HSC) samples are similar in gender and race but differ in age and schooling. Compared with other subjects, members of the HSC group are significantly younger, have completed fewer years of education, and are more likely to be enrolled in school at the time of initial assessment. NPCs are more diverse in terms of gender and race and have completed more years of formal education. The 3 groups are similar in socioeconomic background (measured by level of parental education) and competitive employment at baseline.
Group Comparisons on Selected Demographic, Instrumental Functioning, and Diagnostic Variables
DSM-IV psychotic disorders were not observed among CHR, HSC, and NPC subjects. Mood and anxiety disorders were prevalent in both clinical samples but were absent among NPC subjects. Alcohol-related diagnoses were equivalent in the CHR and HSC groups, but substance abuse/dependence was somewhat more likely among CHR subjects (χ2 = 3.969, [1, 490], P < 0.05). In general, alcohol and drug problems were rare among NPC subjects.