While the arguments for and against inclusion of a risk syndrome have been well aired in this forum, less attention has been paid to the potential content of the proposed criteria.
Current research criteria for the risk syndrome were developed and operationalized more than a decade ago. The primary basis for diagnosis was presence of a single attenuated (subpsychotic) positive symptom. However, these original criteria have exhibited a pattern of decreasing predictive value as study populations have expanded over time (Yung et al., 2008; Cannon et al., 2008).
At the same time, numerous studies have demonstrated that predictive validity of these criteria can be enhanced by 1) increasing the threshold of attenuated positive symptoms required at baseline; and 2) addition of attenuated negative symptoms, basic symptoms, and/or functional deficits to the prediction model (Cornblatt et al., 2003; Lencz et al., [...continued] 2003; Yung et al., 2003, 2004, 2006; Cannon et al., 2008; Velthorst et al., 2009). Additional efforts at refining and operationalizing these criteria are ongoing.
If a risk syndrome is to be introduced in DSM-V (or any future edition), the existing body of empirical evidence should serve as a useful guide to criteria development prior to initiation of any large-scale field trials.
Cannon TD, Cadenhead K, Cornblatt B, Woods SW, Addington J, Walker E, Seidman LJ, Perkins D, Tsuang M, McGlashan T, Heinssen R. Prediction of psychosis in youth at high clinical risk: a multisite longitudinal study in North America. Arch Gen Psychiatry. 2008 Jan;65(1):28-37. Abstract
Cornblatt BA, Lencz T, Smith CW, Correll CU, Auther AM, Nakayama E. The schizophrenia prodrome revisited: a neurodevelopmental perspective. Schizophr Bull. 2003;29(4):633-51. Abstract
Lencz T, Smith CW, Auther AM, Correll CU, Cornblatt BA. The assessment of "prodromal schizophrenia": unresolved issues and future directions. Schizophr Bull. 2003;29(4):717-28. Abstract
Velthorst E, Nieman DH, Becker HE, van de Fliert R, Dingemans PM, Klaassen R, de Haan L, van Amelsvoort T, Linszen DH. Baseline differences in clinical symptomatology between ultra high risk subjects with and without a transition to psychosis. Schizophr Res. 2009 Apr;109(1-3):60-5. Abstract
Yung AR, Phillips LJ, Yuen HP, Francey SM, McFarlane CA, Hallgren M, McGorry PD. Psychosis prediction: 12-month follow up of a high-risk ("prodromal") group. Schizophr Res. 2003 Mar 1;60(1):21-32. Abstract
Yung AR, Phillips LJ, Yuen HP, McGorry PD. Risk factors for psychosis in an ultra high-risk group: psychopathology and clinical features. Schizophr Res. 2004 Apr 1;67(2-3):131-42. Abstract